Impact of the longer change and clearance intervals on ...

University of Central Florida University of Central Florida

STARS STARS

Electronic Theses and Dissertations, 2004-2019

2016

Impact of the longer change and clearance intervals on signalized Impact of the longer change and clearance intervals on signalized

intersections and corridors intersections and corridors

Mohammed Alfawzan University of Central Florida

Part of the Civil Engineering Commons, and the Transportation Engineering Commons

Find similar works at: https://stars.library.ucf.edu/etd

University of Central Florida Libraries http://library.ucf.edu

This Masters Thesis (Open Access) is brought to you for free and open access by STARS. It has been accepted for

inclusion in Electronic Theses and Dissertations, 2004-2019 by an authorized administrator of STARS. For more

information, please contact [email protected].

STARS Citation STARS Citation Alfawzan, Mohammed, "Impact of the longer change and clearance intervals on signalized intersections and corridors" (2016). Electronic Theses and Dissertations, 2004-2019. 4872. https://stars.library.ucf.edu/etd/4872

https://stars.library.ucf.edu/



https://stars.library.ucf.edu/etd

http://network.bepress.com/hgg/discipline/252?utm_source=stars.library.ucf.edu%2Fetd%2F4872&utm_medium=PDF&utm_campaign=PDFCoverPages

http://network.bepress.com/hgg/discipline/1329?utm_source=stars.library.ucf.edu%2Fetd%2F4872&utm_medium=PDF&utm_campaign=PDFCoverPages

https://stars.library.ucf.edu/etd

http://library.ucf.edu/

mailto:[email protected]

https://stars.library.ucf.edu/etd/4872?utm_source=stars.library.ucf.edu%2Fetd%2F4872&utm_medium=PDF&utm_campaign=PDFCoverPages



IMPACT OF THE LONGER CHANGE AND CLEARANCE INTERVALS ON SIGNALIZED

INTERSECTIONS AND CORRIDORS

by

MOHAMMED SALEH ALFAWZAN

B.S. QASSIM UNIVERSITY, 2010

A thesis submitted in partial fulfillment of the requirements

for the degree of Master of Science

in the Department of Civil, Environmental and Construction Engineering

in the College of Engineering and Computer Science

at the University of Central Florida

Orlando, Florida

Spring Term

2016

ii

ABSTRACT

Evaluating the impact of longer change and clearance intervals on signalized intersections

and corridors is the main goal of this study. In fact, the Florida department of Transportation

(FDOT) has adopted a new signal retiming effort in a number of signalized intersections along

several corridors. The Orange County started implementing the new signal timing from December,

2013 and completed it in June, 2015. The other objective of this new signal timing is to minimize

the red light running rate. This study is dedicated to investigate the signal retiming effort adopted

by the FDOT and how the new signal timing might impact the studied signalized intersections’

performance and safety. To address this issue, a number of signalized intersections along three

corridors in Orange County were investigated during different three time of the day periods AM,

MD, and PM. Additionally, three categories of signal timings were adopted to better understand

the performance and safety of old (pattern 1), current (pattern 2), and proposed (pattern 3) signal

timings. The analysis was based on the Simtraffic simulation which is a part of Synchro 8 software.

The research results provide that the signalized intersection’s performance along the three

corridors during the three plans of the day were found significantly affected by lengthening the

change and clearance intervals. Signal timing 2 and 3 were observed significantly different than

signal timing 1 which have greater intersection delay, queue length, intersection overall volume

to capacity v/c ratio, and Intersection capacity utilization ICU. Furthermore, the results show that

the signal timing 2 and signal timing 3 significantly increase the total delay and travel time along

the studied arterials during the three plans of the day.

iii

ACKNOWLEDGMENTS

I take this opportunity to express all my appreciations and thanks to my advisor Professor

Essam Radwan for his encouraging and exemplary guidance while I am doing my master degree.

His constant guidance, encouragement, and patience throughout my thesis built the essential skills

as a researcher. Also, I would like to thank Dr. Hatem Abou-Senna for the valuable advice that he

gave me and for serving as thesis committee member. My thanks and appreciation also for

Professor Naveen Eluru for his acceptance to be as thesis committee member. I would like also to

thank the Orange County Traffic Engineering Department represented by the Chief Engineer

Hazem El-Assar for the valuable information provided by them in their respective fields. I am

grateful for their cooperation during the period of my thesis. Finally, my honorable thanks and

appreciation goes to my father, mother, wife, brothers, sisters and friends for their constant

encouragement, support, and patience without which this assignment would not be possible.

iv

TABLE OF CONTENTS

LIST OF FIGURES ...................................................................................................................... vii

LIST OF TABLES ....................................................................................................................... viii

CHAPTER 1: BACKGROUND AND INTRODUCTION ............................................................ 1

1.1 Introduction ........................................................................................................................... 1

1.2 Research Questions and Research Tasks .............................................................................. 3

CHAPTER 2: RELATED WORK AND LITERATURE REVIEW .............................................. 4

2.1 Definitions ............................................................................................................................. 4

2.2 Green Interval ........................................................................................................................ 4

2.3 Change Interval ..................................................................................................................... 5

2.4 Red Interval ........................................................................................................................... 5

2.5 Change and Clearance Intervals ............................................................................................ 5

2.6 Change and Clearance Intervals Standards ........................................................................... 6

2.6.1 Manual on Uniform Traffic Control Devices (MUTCD) ............................................... 6

2.6.2 Institute of Transportation Engineers (ITE) ................................................................... 7

2.7 The Dilemma and Option Zones ........................................................................................... 9

2.7.1 The Dilemma Zone Issue .............................................................................................. 12

2.7.2 Driver’s Response to Change Indication ...................................................................... 15

2.7.3 The Impact of change Duration on Dilemma/option zones .......................................... 17

2.8 Change Interval Formulas ................................................................................................... 17

2.8.1 Formula 1: Rule-of Thumb Methods ............................................................................ 17

2.8.2 Formula 2: Kinematic Model 1 .................................................................................... 18

2.8.3 Formula 3: Kinematic Model 2 .................................................................................... 18

2.9 Clearance Interval Formulas ............................................................................................... 18

2.10 Florida Change Interval ..................................................................................................... 20

2.11 Florida Clearance Interval ................................................................................................. 20

2.12 Florida Turn Phases ........................................................................................................... 21

CHAPTER 3: DATA COLLECTION AND TOOL USED ......................................................... 22

3.1 Data Collection:................................................................................................................... 22

3.2 Project Intersections ............................................................................................................ 23

v

3.3 Signal Timing ...................................................................................................................... 25

3.3.1 Signal Timing Pattern 1 ................................................................................................ 26



3.4 change and clearance Intervals Data ................................................................................... 29

3.5 Traffic volume and approaches splits data .......................................................................... 30

3.6 Simulation tool .................................................................................................................... 30

CHAPTER 4: TRAFFIC SIGNAL ANALYSIS .......................................................................... 31

4.1 AM peak Signal timing plan ............................................................................................... 31

4.1.1 Signal timing Pattern 1 ................................................................................................. 31



4.1.4 Signal Timing Patterns Evaluation ............................................................................... 34

Signal Timing Patterns Impact on a Corridor ........................................................................ 45

4.2 Midday Signal Timing Plan ................................................................................................ 46





4.2.5 Signal Timing Patterns Impact on a Corridor ............................................................... 58

4.3 PM Signal Timing Plan ....................................................................................................... 60





4.3.5 Signal Timing Patterns Impact on a Corridor ............................................................... 72

4.4 Red Light Running RLR Statistics ...................................................................................... 73

4.5 Dilemma and Option Zones Implemented Study on SR 50 Intersections ........................... 74

4.6 Statistical Analysis .............................................................................................................. 76

CHAPTER 5: CONCLUSIONS AND FINDINGS AND RECOMMENDATIONS................... 81

5.1 Conclusions and Findings ................................................................................................... 81

vi

5.2 Recommendations and Future studies ................................................................................. 83

APPENDIX [A]: SIGNAL TIMING FOR THE STUDIED SIGNALIZED INTERSECTIONS 84

APPENDIX [B]: VOLUME AND SPLITS FOR THE STUDIED SIGNALIZED

INTERSECTIONS ........................................................................................................................ 91

APPENDIX [C]: THE GENERAL CHARACTERISTICS OF THE STUDIED SIGNALIZED

INTERSECTIONS ........................................................................................................................ 97

APPENDIX [D]: THE SIGNAL TIMING EFFICIENCY MEASUREMENTS OF THE

STUDIED SIGNALIZED INTERSECTIONS ........................................................................... 104

APPENDIX [E]: DILEMMA AND OPTION ZONES IDENTIFICATION OF THE STUDIED

SIGNALIZED INTERSECTIONS ............................................................................................. 111

REFERENCES ........................................................................................................................... 114

vii

LIST OF FIGURES

Figure 1 Formation of a Dilemma Zone, (Wei, 2008) .................................................................... 9

Figure 2 Formation of an Option Zone (Wei, 2008) ..................................................................... 12

Figure 3: SR 50 layout ................................................................................................................. 24

Figure 4: SR 50 layout ................................................................................................................. 25

Figure 5: SR 535 & SR 536 layout ............................................................................................... 26

Figure 6: SR 535&536 layout ....................................................................................................... 27

Figure 7: SR 50 Estimated Delay for the Signal Timing patterns ................................................ 35

Figure 8: SR 535 and SR 536 estimated Delay for the Signal Timing patterns ........................... 37

Figure 9: SR 50 95% Percentile Queue length for the Signal Timing patterns ............................ 39

Figure 10: SR 535 and SR 536 95% Percentile Queue length for the Signal Timing patterns .... 40

Figure 11: SR 50 V/C Rate for the Signal Timing patterns .......................................................... 42

Figure 12: SR 535 and SR 536 V/C Ratio for the Signal Timing patterns ................................... 43

Figure 13: SR 50 Intersection Capacity Utilization ICU .............................................................. 44

Figure 14: SR 535 & SR 536 Intersection Capacity Utilization ICU ........................................... 46

Figure 15: SR 50 estimated Delay for the Signal Timing patterns ............................................... 50

Figure 16: SR 535 and SR 536 Estimated Delay for Signal Timing patterns............................... 52

Figure 17: SR 50 95% Percentile Queue length for the Signal Timing patterns .......................... 54


Figure 19: SR 50 V/C rate for the Signal Timing patterns ........................................................... 55

Figure 20: SR 535 and SR 536 V/C rate for the Signal Timing patterns ...................................... 57

Figure 21: SR 50 ICU for Signal Timing Patterns ........................................................................ 58

Figure 22: SR 535 & SR 536 ICU for Signal Timing Patterns ..................................................... 59

Figure 23: SR 50 estimated Delay for the Signal Timing patterns ............................................... 63

Figure 24: SR 535 and SR 536 Estimated Delay for Signal Timing patterns............................... 65

Figure 25: SR 50 95% Percentile Queue length for the Signal Timing patterns .......................... 66


Figure 27: SR 50 V/C Ratio for the Signal Timing patterns......................................................... 68

Figure 28: SR 535 and SR 536 V/C Ratio for the Signal Timing patterns .................................. 69

Figure 29: SR 50 ICU for Signal Timing Patterns ........................................................................ 71

Figure 30: SR 535 & SR 536 ICU for Signal Timing Patterns ..................................................... 72

Figure 31: Average Monthly Red Light Running ......................................................................... 75

viii

LIST OF TABLES

Table 1 Sample Change Intervals, Gaziz, Herman et al. 1960, Parsonson, and Roseveare et al.

1974............................................................................................................................................... 14

Table 2 Sample Red Intervals, Click and Jones 2006, Click 2008 ............................................... 15

Table 3: Florida Yellow Change Interval (0.0 % Grade) FDOT (2002a) .................................... 20

Table 4: Florida Clearance Interval, (FDOT, 2002a) ................................................................... 21

Table 5: Signalized Intersections on SR 50 Corridor ................................................................... 24

Table 6: Signalized Intersections on SR 535 & SR 536 Corridor ................................................ 25

Table 7: Florida Change Interval (0.0 % Grade) *, FDOT Traffic Engineering Manual, 2013 ... 28

Table 8: SR 50 estimated Delay for the Signal Timing patterns .................................................. 34

Table 9: SR 535 and SR 536 estimated Delay for the Signal Timing patterns ............................. 36

Table 10: SR 50 95% Percentile Queue length for the Signal Timing patterns ........................... 38

Table 11: SR 535 and SR 536 95% Percentile Queue length for the Signal Timing patterns ...... 39

Table 12: SR 50 V/C Ratio for the Signal Timing patterns .......................................................... 40

Table 13: SR 535 and SR 536 V/C Ratio for the Signal Timing patterns .................................... 41

Table 14: SR 50 Intersection Capacity Utilization ICU for Signal Timing Patterns .................... 43

Table 15: SR 535 and SR 536 SR ICU for Signal Timing Patterns ............................................. 44

Table 16: Arterials Total Delay per vehicle .................................................................................. 45

Table 17: Arterials Total Travel Time .......................................................................................... 45

Table 18: SR 50 estimated Delay for the Signal Timing patterns ................................................ 48

Table 19: SR 535 and SR 536 Estimated Delay for Signal Timing patterns ................................ 49

Table 20: SR 50 95% Percentile Queue length for the Signal Timing patterns ........................... 51

Table 21: SR 535 and SR 536 Queue length for the Signal Timing patterns ............................... 52

Table 22: SR 50 V/C rate for the Signal Timing patterns ............................................................. 53

Table 23: SR 535 and SR 536 V/C rate for the Signal Timing patterns ....................................... 55

Table 24: SR 50 ICU for Signal Timing Patterns ......................................................................... 56


Table 26: Arterial Total Delay per vehicle ................................................................................... 58

Table 27: Arterial Total Travel Time ............................................................................................ 59

Table 28: SR 50 estimated Delay for the Signal Timing patterns ................................................ 62

Table 29: SR 535 and SR 536 Estimated Delay for Signal Timing patterns ................................ 63

Table 30: SR 50 Queue length for the Signal Timing patterns ..................................................... 64

Table 31: SR 535 and SR 536 Queue length for the Signal Timing patterns ............................... 66

Table 32: SR 50 V/C Ratio percentages for the Signal Timing patterns ...................................... 67

Table 33: SR 535 and SR 536 V/C Ratio for the Signal Timing patterns .................................... 69

Table 34: SR 50 ICU for Signal Timing Patterns ......................................................................... 70


Table 36: Total Arterial Delay per vehicle ................................................................................... 72

Table 37: Total Travel Time on a Corridor .................................................................................. 73

ix

Table 38: Average Monthly RED Light Running......................................................................... 74

Table 39: Dilemma and Option Zones Identification of Intersection 2 ........................................ 75

Table 40: SR 50 Paired t-test of signal Timing Patterns during AM Plan .................................... 76

Table 41: SR 535&536 Paired t-test of signal Timing Patterns during AM Plan ......................... 77

Table 42: SR 50 Paired t-test of signal Timing Patterns during Midday Plan .............................. 78

Table 43: SR 535&536 Paired t-test of signal Timing Patterns during Midday Plan ................... 78

Table 44: SR 50 Paired t-test of signal Timing Patterns during PM Plan .................................... 79

Table 45: SR 535&536 Paired t-test of signal Timing Patterns during PM Plan ......................... 80

1

CHAPTER 1: BACKGROUND AND INTRODUCTION

1.1 Introduction

With the advent of automobile revolution, traffic engineering science has become a crucial

need. It is associated with the planning, monitoring, geometric design and traffic operations of

highways and their networks, so that people and goods travel faster and safe. In this research, a

new signal timing standard, adopted by the Florida State Department of Transportation (FDOT)

on a number of signalized intersections is researched in several aspects. The research investigated

the before, after and a proposed signal timing systems of signalized intersections along different

corridors. In order to evaluate the impact of lengthening the change (yellow) and clearance (Red)

intervals on the individual intersections and the network’s performance and safety, three signal

timings categories are investigated along different corridors. The effort of change and clearance

retiming intervals was approved by the (FDOT). Traffic engineers designed the new signal timing

based on the Institute of Transportation Engineers (ITE) that uses kinematic equation for

calculating the vehicle clearance interval and change period.

Change and clearance intervals are utilized to smooth and protect the traffic movement of

signalized intersections. The change indication is designed to warn oncoming traffic that the green

interval is almost vanished. Therefore, the clearance interval is required for all approaches to

protect any vehicle entering the intersection during the change interval to clear the intersection

safely before any conflicting movements are released. The new signal time design increased the

change and clearance intervals in order to minimize the dilemma zone size and the red light running

(RLR) frequency.

2

The dilemma zone is defined as a zone of an intersection approach where a driver has to

stop or move safely through the intersection during the change indication. It is also considered as

a hazard area where a driver might have lack of time to safely enter the intersection or stop before

the stop bar. Thus, to mitigate that, traffic scientist defined another zone called the option zone.

Option zone is formed when the change interval is long enough for a motorist to either stop safely

or pass through the intersection before the end of the change interval. Therefore, driver’s decision

of either go through the intersection or stop is optional. The signal retiming adopted by the (FDOT)

is designed to overcome the lack of change time leading to an increase of red light running.

In general, Signal timing can significantly affect the red light running. A number of

scholars studied this particular phenomenon and its impact on signalized intersections safety and

efficiency. In fact, they observed that lengthening the change interval by certain time could

decrease the red light running rate. As a result, the traffic engineers of the (FDOT) have decided

to lengthen the change interval of such signalized intersections by certain seconds to minimize the

RLR frequency.

In the following chapters, three signal timing patterns of a number of signalized

intersections along three corridors in the State of Florida are investigated. The three signal timing

patterns have different yellow and clearance intervals based on certain techniques which will be

explained in chapter 3. Those signal timing patterns were investigated and analyzed using Synchro

8 software to evaluate the signal retiming impact on the studied signalized intersections and

corridors performance and safety.

3

1.2 Research Questions and Research Tasks

The objective of this research can be summarized in the following questions:

1. Does the new signal timing based on lengthening the change and clearance intervals

significantly affect the intersections and corridors performance?

2. Does the new signal timing of lengthening the change and clearance intervals significantly

improve signalized intersections’ safety?

3. Does the additional change interval based on a Perception and Reaction Time PRT of 1.4 and

2 seconds significantly minimize the dilemma zone and extend the option zone?

4

CHAPTER 2: RELATED WORK AND LITERATURE REVIEW

`In this chapter, a review of previous relevant literature of change and clearance intervals

is briefed. In addition, a study of various techniques and standards of estimating change and

clearance intervals is further discussed in order to have a better understanding of signalized

intersections’ timing. Dilemma zone is also investigated to reflect its impact on the signalized

intersections and how a change interval duration can minimize the size of the zone.

2.1 Definitions

Most definitions listed below are cited from the manual on Uniform Traffic Control

Devices and the Uniform Vehicle Code (Code & Ordinance, 2000). Most US states follow the

definitions in these two manuals unless some states differ and not all confirm the following

definitions

2.2 Green Interval

The green interval is a fixed period of time that is dedicated for traffic to go straight through

the intersection or turn right or left as allowed by opposing traffic unless the movements restricted

by such a reason such as turn prohibition, lane markings, or geometric design of the intersection

roadway. Traffic facing a green light (shown alone or with another indication), may go through

the intersection to make a movement that is protected by such an arrow or permitted by different

indications at the same time. Motorists who turn right or left have to yield the right- of- way to

other vehicles and pedestrians inside the intersection or the adjacent crosswalk on the time when

a signal indication is shown.

5

2.3 Change Interval

Traffic facing a solid yellow or yellow arrow light is noticed that the current green

movement is almost gone or a red indication may be risen in a moment thereafter. The standards

provide that a solid yellow or yellow arrow should be exhibited after every solid green or green

arrow intervals.

2.4 Red Interval

Traffic facing a solid red or a red arrow light have to stop before the marked stop line or if

none, before reaching the marked crosswalk and if none, before reaching the intersection, and must

remain stop at the intersection until a green indication arises (the red interval definition does not

prevent the right turn movement on red after stop, as allowed and described in many standards).

2.5 Change and Clearance Intervals

A number of resources and literatures searching the topic of signal design state that the

term of change and clearance intervals have been major elements used in several ways (Knodler

Jr & Hurwitz, 2009). The change interval is designed to warn oncoming traffic that the right-of-

way allocated to the current approach is almost to be vanished (Pline, 1999). It alerts oncoming

vehicles that are faced by green indication, and which has insufficient stopping distance to slow

down and safely stop before the stop line, while it allows for vehicles reaching an intersection to

maintain their speed and legally inter the intersection during the change light (Knodler Jr &

Hurwitz, 2009).In the Traffic Engineering Handbook, traffic engineers stated that the standard

duration for the change period at a high-speed intersection is about five seconds(Pline, 1999).The

clearance interval is such a red indication for all approaches that is dedicated to protect any vehicle

entering the intersection during the change interval to clear the intersection safely before any

6

conflicting movements are released (Knodler Jr & Hurwitz, 2009). In traffic Engineering

Handbook Pline (1999) engineers stated that the standard duration for the clearance interval at a

high-speed intersection is about two seconds.

2.6 Change and Clearance Intervals Standards

2.6.1 Manual on Uniform Traffic Control Devices (MUTCD)

In the United States of America, The Manual on Uniform Traffic Control Devices MUTCD

(2003) is the green book that is widely implemented on the application of traffic signs, pavement

marking, and traffic signals (McGee et al., 2012). “The MUTCD (2003) is somewhat limited in its

guidance of change and clearance intervals, beyond the basics. However, this is appropriate since

this is fundamentally a question of signal timing, existing outside the parameters of the MUTCD

(2003). The MUTCD (2003) has discussed the recommended change interval fall in the range of

three to six seconds (McGee et al., 2012). It is stated that the longer change intervals should be

allocated for approaches that have high posted speeds (MUTCD, 2003). Finally, the manual

provides that engineering practices for determining the duration of change and clearance intervals

can be found in ITE’s “Traffic Engineering Handbook (1999)” and in ITE’s “Manual of Traffic

Signal Design,(1989)” (see Section 1A.11).

Similarly, the clearance interval is stated by the similar manual in such different standards.

The clearance interval standards listed in the MUTCD (2003) show that, “The duration of a

clearance interval shall be predetermined.” While, the guidance states that, “A red clearance

interval should have a duration not exceeding 6 seconds.”

7

2.6.2 Institute of Transportation Engineers (ITE)

ITE is considered well respected technical resource for traffic engineers on traffic

engineering issues. In 1985, a practical recommended manual was released by ITE based on

kinematic equation for calculating the “vehicle clearance interval” or “change period”:

CP = t +V

2a+64.4 g+

W+L

V (1)

Where:

CP = change period (s);

t = Perception Reaction Time PRT (usually 1 s);

V = approach speed (ft/s);

a = deceleration rate (ft/s2);

g = percent of grade divided by 100 (plus for upgrade, minus for downgrade);

W = width of intersection (ft); and

L = length of vehicle (ft).

A number of agencies use this equation to calculate the change time even though ITE never

officially embraced this recommended practice. The equation calculates the time for a driver to

react and perceive to the change in order to maintain his speed and enter the intersection safely or

decelerate and stop comfortably prior to a change in right-of-way (McGee et al., 2012). The first

two terms of equations is designed to estimate the change interval while the third term is allocated

to estimate the clearance interval.

8

According to ITE Traffic Engineering Handbook (1999), the change interval is calculated as

follow:

Y = t +V

2a+2Gg (2)

Where:

Y = Change interval (s);

t = reaction time (typically 1 s);

V = design speed (ft/s);

a = deceleration rate (typically 10 ft/s2);

G = acceleration due to gravity (32.2 ft/s2); and

g = grade of approach (percent / 100, downhill is negative grade).

The current ITE Traffic Engineering Handbook discuses only one equation that calculates

the clearance interval. It is stated that, the clearance interval is considered as an optional period of

time coming right after the change interval and precedes the next green interval. It is used to add

additional time for the change interval prior to the conflicting traffic is released. The r clearance

interval should be estimated using the equation listed in ITE’s Determining Vehicle Signal Change

and Clearance Intervals (ITE, 1985; Pline, 1999) as illustrated below:

R =W+L

V (3)

Where:

9

R = Clearance interval (s),

V = design speed (ft/s),

W = width of stop line to far-side no-conflict point (ft), and

L = length of vehicle, typically 20 ft.

It is worth mentioning that using the clearance interval is based on intersection geometrics, crash

experience, pedestrian activity, approach speeds, local practices, and engineering judgment (ITE,

1985)

2.7 The Dilemma and Option Zones

The dilemma zone can be defined as a certain area of an intersection approach where a

driver is warned by the change indication has to decide to stop or continue movement through an

intersection (McGee et al., 2012). Dilemma zone was early described by Gazis, Herman, and

Maradudin (1960) who found that a driver presented by a change interval indication and

approaching a signalized intersection will have lack of time to safely enter the intersection or stop

before the stop bar (McGee et al., 2012), see Figure 1.

Figure 1 Formation of a Dilemma Zone, (Wei, 2008)

10

Xc refers to the critical distance or the minimum stopping distance from stop bar.

Therefore, within a closer distance from the stop line than Xc, a vehicle cannot safely stop before

the stop line. 𝑋0 is the maximum distance a vehicle can travel during the change interval and clear

the intersection before the end of change interval in which refers to the maximum change passing

distance from the stop line (Wei, 2008). 𝑋𝑐 𝑎𝑛𝑑 X0 can be computed by Equations (4) and (5)

(Gazis et al., 1960):

Xc = V0 δ2 +V02

2a2 (4)

X0 = V0τ − W +1

2 a1(τ − δ1)2 (5)

Where:

V0 = the approach speed (ft/s);

𝛿2= the driver’s perception-reaction time (sec);

𝑎2 = the maximum vehicle’s deceleration rate (ft2/s); 1

𝛿1 = the driver’s perception-reaction time for running (sec);

𝑎1 = the constant vehicle’s acceleration rate (𝑓𝑡2/s);

τ = the duration of change interval (sec);

W = the summation of intersection width and the length of vehicle.

11

When Xc > X0 which means change interval passing distance is greater than the minimum

stopping distance, the vehicle within the “zone” between Xc and X0 at the beginning of the change

indication faces two options: either go through the intersection or slow down and stop before the

stop bar during the change time. The “zone” between XC and X0 (XC > X0) is considered as

option zone, (Wei, 2008) as shown in Figure 2.

An option zone can be defined as a zone within the onset of change interval, a driver can

either stop safely or pass through the intersection before the end of the change interval. The zone

is located where driver’s decision of either go through the intersection or stop is optional (Wei,

2008).

A number of definitions are shown in the literature by different scholars attempting to

define the dilemma zone. The reason being that the ITE recommended equations treat the traffic

flow as deterministic events and that all vehicles approaching the intersection keep the posted

speed limit. In reality though, speed varies among drivers and the assessment of travel time is more

stochastic in nature. Zegeer (1977) described the boundaries of the dilemma zone as decision taken

by a driver in a certain point of intersection approach. He defined the beginning of the zone in a

point where 90% of drivers tend to stop and while the end of the zone located where 10% of drivers

tend to stop. In 1985, a decision was made to adopt travel time to the stop bar as the boundary of

dilemma (Chang, Messer, & Santiago, 1985). He used this term to identify the boundaries to

measure the travel time from the stop bar. The researcher found that 85% of motorists stop where

they are three seconds or more back from the stop bar while the majority of drivers tend to continue

through the intersection where they are two seconds or less from the stop bar. To conclude that, it

12

is found that the dilemma zone located in the range between 5.5 seconds and 2.5 seconds from the

stop bar (Knodler Jr & Hurwitz, 2009).

Figure 2 Formation of an Option Zone (Wei, 2008)

Parsonson (1992) and Si, Urbanik, and Han (2007) believed that the dilemma zone and

option zone are theoretically different issues, even though the boundaries of the dilemma and

option zones may overlap to a certain level. The dilemma zone can be eliminated by appropriate

change and clearance duration while the option zone is always exist at a particular area of an

approach, (Wei, 2008).

2.7.1 The Dilemma Zone Issue

Dilemma zone has a potential negative influence on the operational capacity and safety of

signalized intersections. Therefore, to address this issue, traffic scholars had come with several

proper solutions to overcome its negative impact. To mitigate dilemma zone impact on signalized

13

intersections, the signal timing was studied to increase the degree of safety and efficiency of such

signalized intersections.

2.7.1.1 Signal Timing

Signal timing methods is considered as a critical element taken by scholars to research its

impact on signalized intersection safety and capacity. For instance, traditional signal timing and

recommend timing practices of change and clearance intervals have been investigated by the North

Carolina Department of Transportation (NCDOT), to address the concern of signal timing on

signalized intersection safety and capacity (Click, 2008; Click & Jones, 2006).

After much investigation and evaluation of proposed alternatives, the task force nominated

a proper alternative to the signal timing method of change and clearance intervals based on ITE

equations (ITE, 1985). The project followed the ITE change interval estimation. However, the

perception reaction time of 1.5 seconds and the deceleration rate of 11.2 ft/s/s recommended by A

Policy on Geometric Design of Highways and Streets were adopted in the estimation of change

and clearance intervals (Aashto, 2001). Therefore, any calculated change time to be less three

seconds was rounded up to a minimum time of 3.0 seconds and holding a stakeholders to accept

any change interval above 6 seconds (Click, 2008; Click & Jones, 2006).Table1 shows sample

results for the revised standard of the ITE change interval estimation.

14

Table 1 Sample Change Intervals, Gaziz, Herman et al. 1960, Parsonson, and Roseveare et al.

1974

Speed Grade mph -6% -3% 0% 3% 6%

20 3.1 3.0 2.9* 2.8 2.7* 25 3.5 3.3 3.2 3.1 2.9*

30 3.9 3.7 3.5 3.4 3.2

35 4.3 4.1 3.8 3.7 3.5

45 5.1 4.8 4.5 4.3 4.1

55 5.9 5.5 5.2 4.9 4.6

65 6.7+ 6.2+ 5.8 5.5 5.2

*: Less than 3.0 second minimum, increase change time to 3.0

+: Greater than 6.0 second threshold, requires stakeholder meeting prior to approval

However, the project committee was very concerned with the increasing of clearance

intervals. Therefore, they advocated using a modified formula to calculate any clearance interval

to be above 3 seconds using equation 6:

𝑟 =1

2(

𝑊

𝑉− 3) + 3 (6)

r = length of clearance interval (seconds)

W = width of intersection (ft)

V = 15th percentile speed (ft/s)

As a result, it is recommended that any clearance interval to be lower than 1 second should be

increased to 1 second and any clearance interval that is greater than 4 seconds would need a

stakeholder meeting. See Table 2 that illustrates the results of the revised standard of ITE interval

calculation.

15

Table 2 Sample Red Intervals, Click and Jones 2006, Click 2008

Speed Clearance Distance (feet)

mph 50 75 100 125 150 175 200 20 1.8 2.6 3.3 3.7 4.1+ 4.5+ 5.0+

25 1.4 2.1 2.8 3.3 3.6 3.9 4.3+

30 1.2 1.8 2.3 2.9 3.3 3.5 3.8

35 1.0 1.5 2.0 2.5 3.0 3.3 3.5

45 0.8* 1.2 1.9 1.9 2.3 2.7 3.1

55 0.7* 1.0 1.6 1.6 1.9 2.2 2.5

65 0.6* 0.8* 1.4 1.4 1.6 1.9 2.1

*: Less than 1.0 second minimum, increase all read time to 1.0

+: Greater than 4.0 second threshold, requires stakeholder meeting prior to approval

2.7.1.2 The Impact of Signal Timing on Red light Running

The impact of signal timing on red light running (RLR) has been investigated in several

studies to assess the impacts of lengthening change intervals on red light running (RLR) rates.

Retting, Ferguson, and Farmer (2008) proved that increasing of amber time lengths by 1.0 second

on studied signalized intersection approaches reduced RLR rates by almost 36% with a 95

confidence interval. In addition, Bonneson and Zimmerman (2004) observed an increase of the

change interval by 1 second can ideally decrease the RLR rate by 50 percent.

2.7.2 Driver’s Response to Change Indication

Dilemma zone is significantly impacted by driver’s response to the change signal

indication. A major effort has been taken by traffic scientists to study the correlation between

driver’s behavior and dilemma zone. Olson and Rothery (1961) continued studying Gazis et al.

(1960) research of dilemma zone and behavioral indications that commonly taken in decision

making at the onset of change indication. They observed a significant point that the driver’s

response does not change from change indication duration to another. El-Shawarby, Rakha, Inman,

16

and Davis (2006) investigated an experiment consisting of 60 drivers to study driver’s behavior

during the change interval. 60 derivers of various ages and sex were hired to drive a test vehicle at

a test roadway system. A number of factors were taken in account in this experiment like real time

speed and distance from stop bar. Those different factors were collected from field and connected

to communication and computer system. It was found from the experiment that drivers stop at five

predetermined distances. Therefore, they recorded the different distances and made a diagram

showing the relationship of stopping vs. distance from the stop line. It was found that 10% and

90% of the drivers would stop at certain locations and that motivated the researcher to identify the

location of the option zone. The research dictated that at the speed of 45 mph, the dilemma zone

was located between 108ft to 253ft from the stop line.

Another significant measure related to the driver behavior during the change interval is

driver’s perception – reaction time (PRT) which significantly affects the location of a dilemma

zone (Wei, 2008). PRT is the time interval that is taken by a driver perceiving the change indication

to the moment when the brake pedal is applied (Rakha, El-Shawarby, & Setti, 2007). It is usually

observed as the time from onset of the change indication until the brake light is noticed. Several

studies have been conducted to estimate the PRT in several environments. Taoka (1989) found

that the 85th-percentile PRT is in the range between 1.5-1.9 sec. Chang et al.(1989), studied the

PRT and driver’s behavioral response and observed that speed significantly influences the median

PRT which is almost 0.9 sec at speed equal or greater than 45 mph. furthermore Caird, Chisholm,

Edwards, and Creaser (2007) conducted a simulation experiments consisting of 77 drivers that

focused on their driving behavior and found that the distance from stop line also influences the

17

PRT ,which is ranging from 0.86 sec for drivers who are close to the stop line to 1.03 sec for

drivers who are far from it.

2.7.3 The Impact of change Duration on Dilemma/option zones

Within the past few decades, a number of studies investigate the influence of change

duration on dilemma and option zones. Saito, Ooyama, and Sigeta (1990) researched the

characteristics of dilemma zones and option zones using a video instrument. The video recording

was used in the research to catch the speed, distance, driver’s PRT and deceleration rate of vehicle

at the beginning of change interval. The research’s results indicated that as the duration of change

interval increases, the number of vehicles in the dilemma zone decreases while the number of

vehicles in the option zone increases. Additionally the area of the dilemma zone deceases while

the area of option zone increases. Also, their research proved that the dilemma and option zones

are majorly dependent on the driver behavior and decision whether to pass or stop during short

interval of time.

Köll, Bader, and Axhausen (2004) researched the change duration impact on dilemma zone

and found that lengthening of the change interval does not improve the intersection safety since it

creates longer option zones. The outcome has the same issue of leading drivers to experience

uncertainties of whether to stop or continue through the intersection.

2.8 Change Interval Formulas

2.8.1 Formula 1: Rule-of Thumb Methods

The rule of –thumb method is commonly used by engineers to estimate the duration of the

change interval. Basically, they use the approach speed in miles per hour and divide it by 10

18

(Pline, 1975). Approach speed can be defined as the higher of the 85th percentile speed or the

posted speed limit (Thompson, 1994). Therefore, the change interval lengths are proposed to be

within approach of speed up to 35 mph, the change interval is three seconds; four seconds for

approach speed from 35 mph to 50 mph; and five seconds for approach speed greater than five

seconds (Kennedy, Kell, & Homburger, 1963).

2.8.2 Formula 2: Kinematic Model 1

This method basically relies on three major factors which are PRT, the vehicle initial speed,

and a comfortable average deceleration before entering the intersection to determine the length

of minimum change interval as mentioned in Equation 2. Kinematic Model 1 is the formal

equation used to estimate the change interval based on the standard average deceleration shown

in the ITE Transportation Engineering and traffic Engineering Handbook, (1982).

2.8.3 Formula 3: Kinematic Model 2

This formula is basically used to provide such enough change interval to allow vehicles

that chose not to stop and continue moving through an intersection if a clearance interval is not

used (Thompson, 1994).The traffic Control Device Handbook (1983) advocates lengthening the

amber interval to allow a vehicle to clear an intersection using Equation 1.

2.9 Clearance Interval Formulas

Clearance interval is calculated using several formulas that allow a vehicle choose not

stop and travel through to clear an intersection during a certain period of time. These equations

are used by several agencies as following:

R =W+L

V (7)

19

R =P

V (8)

R =P+L

V (9)

Where:

R = Length of the clearance interval;

W= width of the intersection, in ft, measured from the near-side stop bar to the far edge the

conflicting traffic lane along the actual vehicle path;

P= width of the intersection, in ft, measured from the near-side stop bar to the far side of the

farthest conflicting pedestrian crosswalk along the actual vehicle path;

L= length of vehicle, in ft assumed to be 20 ft;

V = design speed (ft/s) (Thompson, 1994).

The three equations 7, 8, and 9 of clearance interval are used to relate the characteristic of

such an intersection and the area of conflict. For instance, equation 1 is utilized to locate the vehicle

in the location that is completely out of the area of conflict with vehicular traffic that is almost to

move and receive a green indication. Equation 2 is used to place a vehicle out of the area of conflict

with pedestrians waiting to cross the far side crosswalk. Equation 3 is designed to clear a vehicle

out of the area of conflict with both vehicular and pedestrian’s traffic (Thompson, 1994).

20

2.10 Florida Change Interval

The Florida State uses the ITE formula Equation 2 found in ITE’s Traffic Engineering

Handbook, (1999) to calculate the yellow change intervals shown in Table 3. These intervals are

the required minimums which are rounded if need up to the next 0.5 second, (FTEM, 2010).

Table 3: Florida Yellow Change Interval (0.0 % Grade) FDOT (2002a)

Approach Speed (mph)

Change Interval (Seconds)

25 3.0

30 3.2

35 3.6

40 4.0

45 4.3

50 4.7

55 5.0

60 5.4

65 5.8

For approach grades other than 0%, Use ITE Formula, Equation 2

2.11 Florida Clearance Interval

The Florida State uses the ITE equation 3, found in ITE’s Traffic Engineering Handbook,

(1999) to compute the minimum clearance interval. Table 4 shows the clearance interval for

intersections having natural characteristics for divided and undivided facilities. However, those

intersections that have particular issues with distance, single point interchanges, and intersections

with widths over than shown in the table, the clearance interval is calculated using equation 3. The

clearance interval duration should not exceed 6 seconds.

21

Table 4: Florida Clearance Interval, (FDOT, 2002a)

Traveled Distance 30 46 58 70 73 85 109 121 133

Approach Speed (Mph) clearance (seconds)

25 1.4 1.8 2.1

30 1.1 1.5 1.8 2.0

35 1.0 1.3 1.5 1.7 1.8

40 0.9 1.1 1.3 1.5 1.6 1.8 2.2 2.4 2.6 45 0.8 1.0 1.2 1.4 1.4 1.6 2.0 2.1 2.3

50 0.7 0.9 1.1 1.2 1.3 1.4 1.8 1.9 2.1 55 0.6 0.8 1.0 1.1 1.2 1.3 1.6 1.7 1.9

60 0.6 0.7 0.9 1.0

65 0.5 0.7 0.8

Empty Cells: Uncommon Parameters

2.12 Florida Turn Phases

For turn Phases, Florida uses Table 3 and Table 4 for protected left or right turns

terminating at the same time with the adjacent through phase for the change and clearance

intervals based on speed. However, equation 3 and 4 are used to compute the change and

clearance intervals where a protected left or right turn does not terminate concurrently with the

adjacent through phase (FDOT, 2002a).

For protected left or right turns, the change and clearance intervals are selected from Table

3 and Table 4 based on the speed. While permissive left or right turns change and clearance

intervals are identified by the concurrent through phase (FDOT, 2002a).

22

CHAPTER 3: DATA COLLECTION AND TOOL USED

3.1 Data Collection:

The Florida State Department of Transportation (FDOT), has started a new project that adopted

a new signal timing. The characteristic of the new signal timing is studied by traffic scholars who

found that it has a positive impact on the intersection safety and efficiency, (Bonneson &

Zimmerman, 2004; Retting et al., 2008). Therefore, the FDOT implemented signal retiming effort

on a number of intersections along several corridors. The signal retiming has been implemented

on intersections starting from 2011 and completed on 2015. The Florida Department of

Transportation has retained a number of consultants to perform a signal system retiming effort for

multiple intersections along multiple corridors. The data collection and the signal retiming effort

includes:

Data Collection (seven day and turning movement counts, intersection inventories and

existing timing data).

Field reviews to observe and understand intersection and system wide traffic flow, system

wide intersection operational malfunctions and deficiencies.

Model and calibrate existing conditions as baseline for analyses.

Update local controller timings and develop three coordination timing plans.

Develop the “time of day” plans.

System timing development, implementation, fine-tuning and post implementation

monitoring.

23

In conclusion, four reports provided by Orange County, FDOT for the signal retiming

project for 20 intersections along 3 corridors are used to study the impact of lengthening the

duration of the change and clearance intervals on the intersections and all along the relevant

corridors. Those corridors are: SR535, SR536, and SR 50, see Figure 3, 4, 5, and 6.The signal

retiming reports include before and after signal timings. The signal timing, volume counts and

other intersections parameters of SR 353 and SR 536 which are intersected with each other are

taken from reports dated on May 2011(OrangeCounty, 2011b) and June 2014(OrangeCounty,

2014). In addition, the signal timing, volume counts and other intersections parameters of SR

50 are cited from reports dated on august 2011(OrangeCounty, 2011a) and March 2015

(OrangeCounty, 2015) for before and after periods.

3.2 Project Intersections

The project intersections are located along three arterials:

a) SR 50

b) SR 535, and

c) SR 536.

I. SR 50

Table (5) illustrates the signalized intersections along SR 50 corridors which starts from

Vizcaya Lakes Road and ends by SR 435 (Kirkman Road), see Figures (3) and (4).

24

Table 5: Signalized Intersections on SR 50 Corridor

Int. No. Arterial Cross Street

1 SR 50 Vizcaya Lakes Road

2 SR 50 Good Homes Road

3 SR 50 Apopka Vineland Road

4 SR 50 Dorscher Road

5 SR 50 Highland Lakes Center

6 SR 50 CR 435 (Hiawassee Road)

7 SR 50 Powers Drive

8 SR 50 Paul Street

9 SR 50 Hastings Street

10 SR 50 SR 435 (Kirkman Road)

Figure 3: SR 50 layout

II. SR 535 & SR 536

Table (6) shows the signalized intersections along SR 535 and SR 536 corridors which

interest with each other. It involves eight signalized intersections along the SR 535 and two

signalized intersections along the SR 536, Figures (5) and (6) illustrates the study frame.

25

Table 6: Signalized Intersections on SR 535 & SR 536 Corridor

Int. No. Arterial Cross Street

11 SR 535 SR 536

12 SR 535 Meadow Creek Drive

13 SR 535 Vineland Ave/I-4 EB Ramp

14 SR 535 I-4 Off Ramp

15 SR 535 Hotel Plaza Blvd

16 SR 535 Palm Parkway/CR 535

17 SR 535 Vinings Way Blvd

18 SR 535 Lake Street

19 SR 536 World Center Dr.

20 SR 536 International Dr.

Figure 4: SR 50 layout

3.3 Signal Timing

The (FDOT) performed a signal system retiming effort along a number of corridors in

several counties. In this project, 20 signalized intersections data along three corridors were

collected or calculated using revised 2010 and 2013 Florida Traffic Engineering Manuals (2002)

26

based on three different patterns. Data pattern1 is the before data which is the signal timing of the

20 signalized intersections before 2011. Secondly, data pattern 2 which is the current signal timing

data of the 20 signalized intersections. Thirdly, data pattern 3 which is a proposed pattern by the

author that is considered in this research to predict the traffic operation if a PRT of two seconds is

implemented.

Figure 5: SR 535 & SR 536 layout

3.3.1 Signal Timing Pattern 1

Signal timing of Pattern 1 was based on ITE change and clearance equations 1, 2, and 3.

The old signal timing of change interval was implemented on the intersections with a PRT of 1

second which is recommended by ITE based on kinematic equation for calculating the “vehicle

clearance interval” or “change period”(FDOT, 2002a; ITE, 1985). Estimated change intervals of

before signal timing for Florida State’s signalized Intersections are listed in Table 3.

27

Figure 6: SR 535&536 layout

The all-red clearance interval values were computed using ITE’s clearance interval formula

found in ITE’s Traffic Engineering Handbook (1999), and the FDOT Traffic Engineering Manual,

(2010). Table 4 shows the minimum clearance interval of before signal timing system based on

posted speed.


The revised 2013 FDOT Traffic Engineering Manual FDOT (2002b) provides

modifications of change and clearance intervals standardization for Signalized Intersections.

Traffic Engineering Manual (2013) states longer minimum change interval. The PRT of change

interval is increased from 1 second to 1.4 second. Table 7 found in revised FDOT Traffic

Engineering Manual (2013) shows the new standardization of the minimum change interval for

signalized intersections based on speed limit.

The clearance interval is estimated using engineering practices. The values are typically calculated

using Equation 3 found in ITE’s Traffic Engineering Handbook (1999) and the FDOT Traffic

28

Engineering Manual (2002), see table 4. The manual states a minimum value of 2.0 seconds and a

maximum value of 6.0 seconds for clearance interval. Furthermore, longer clearance interval than

2 seconds may be implemented based on an intersection characteristic and engineering judgment

(FDOT, 2002b).

Recently, the engineering committee of Florida department of Transportation advocated

lengthening the clearance intervals of signalized intersections on a number of corridors in several

counties by using such a technical method to provide adequate clearance intervals. Clearance

intervals can significantly affect intersection safety by reducing the frequency of right angle

crashes (FDOT, 2002b). The method typically based on engineering judgment and intersections

characteristic. Therefore, the lengthening of the intersection clearance interval is computed using

Equation 3 found in ITE’s Traffic Engineering Handbook, (1999). However, the new technique

mainly relies on using lower posted speed of such an intersection to compute the clearance. For

instance, 25 mph posted speed is used to calculate the clearance interval of high speed left turn

approaches at signalized intersections.

Table 7: Florida Change Interval (0.0 % Grade) *, FDOT Traffic Engineering Manual, 2013

Approach speed

(mph)

Change interval

(seconds)

25 3.4

30 3.7

35 4.0

40 4.4

45 4.8

50 5.1

55 5.5

60 5.9

65 6.0

* For approach grades other than 0%, Use ITE Formula, Equation 2.

29


Signal timing of Pattern 3 is based on ITE change and clearance equations 1, 2, and 3.

However, a proposed minor modification is implemented on pattern 2 to prolong the change

interval using PRT of 2.0 seconds. The proposed pattern is adopted in this research to evaluate: 1.

the productivity of the intersections system along the three corridors when longer PRT is used, 2.

how the longer PRT impacts the entire signalized intersections safety, and 3. How the proposed

signal timing is different from pattern 1 to pattern 2.

3.4 change and clearance Intervals Data

Signal timing data in this research was gathered from four reports provided by Orange

County, FDOT for 20 intersections along 3 corridors or calculated based on revised FDOT Traffic

Engineering Manuals, (2010, 2013). Before and current change intervals are totally collected from

the four reports while the proposed change intervals are calculated using a PRT of 2.0 seconds.

The before and current clearance intervals are calculated using Equation 3 found in ITE’s Traffic

Engineering Handbook (1999). However, current all-red intervals are computed using lower speed

limit of 25 mph for left turn approaches and (-5.0_-10) mph for through approaches based on the

signal retiming project implemented after 2011. Tables (1-20) found in Appendix (A) shows the

signal timing for the 20 signalized intersection in three different patterns. They show the change

and clearance intervals for patterns 1, 2, and 3. To conclude up, pattern1 signal timing is composed

of before change and clearance intervals. Additionally, pattern 2 signal timing is composed of

current change and current clearance intervals timing while pattern 3 signal timing is consisted of

proposed change and current clearance intervals timing.

30

3.5 Traffic volume and approaches splits data

Twenty signalized intersections turning movement counts and splits timing data during

three period of time are gathered from the four reports provided by Orange County, FDOT for the

signal retiming project, see Appendix B, Tables (1-20).

3.6 Simulation tool

In this research, Synchro 8 software is utilized to simulate three different patterns of signal

timing for 20 signalized intersections along three corridors. The main objective of using synchro

8 is to investigate the performance of the 20 signalized intersections all along the three arterials.

Basically, SimTraffic, which is a micro-simulation model as a part of Synchro 8, is used to measure

three major parameters of each pattern. The three parameters are intersection delay per vehicle in

seconds, the critical left turn movement 95th percentile queue length in feet of intersection,

intersection volume to capacity ratio v/c ratio, and Intersection capacity Utilization ICU. Eighteen

hours of simulation runs were implemented on three patterns composing of 20 signalized

intersection through three arterials during three different time of day plans which are AM peak,

midday, and PM peak.

31

CHAPTER 4: TRAFFIC SIGNAL ANALYSIS

In this chapter, three signal timing patterns implemented on 20 signalized intersections

along three corridors were investigated during three time periods namely AM peak, midday, and

PM peak. To investigate the impact of lengthening the change and clearance intervals timing on

intersections and arterial efficiency, three major parameters are assessed. The three studied

parameters are: the intersection delay per vehicle in seconds, volume to capacity ratio, and the

critical left turn movement 95% percentile queue length in feet. The critical left turn movement

means the heist traffic volume left turn approach of the intersection. Finally, the equations of

dilemma and option zones were utilized to study the impact of the three signal timing patterns of

extending change and clearance phases on intersections’ safety.

4.1 AM peak Signal timing plan

The AM peak plan analysis section consists of three signal timing patterns to 20 signalized

intersections along three arterials. A list of tables and graphs are illustrated that show delay, 95 %

percentile queueing length of the critical left turn movement, and v/c ratio of the studied signalized

intersections during morning peak plan.

4.1.1 Signal timing Pattern 1

AM peak signal timing Pattern 1 was implemented on SR 50, SR 535, and SR 536 intersections

before (FDOT) performed the signal system retiming project. Generally, the cycle’s length of SR

50 corridor was 150 seconds and 170 seconds for most intersections. SR 535 and SR 536 signal

timing composed of 160 seconds for most intersections.

32

4.1.1.1 Intersections Characteristics and Efficiency Measurements

The characteristic of signalized intersections is a significant criteria that contribute with other

factors to impact intersection’s safety and efficiency. It mainly relies on signal timing, phasing

splits, and intersection geometry. Split phasing can be defined as a right of way movement of a

particular approach, followed by all the movements of opposing approach. Split phasing is utilized

to avoid the traffic conflicting of opposing left turn vehicles (Pline 1999). Appendix (C) illustrates

the studied intersections traffic features on the three corridors, such the number of intersection’

approaches and splits.

Synchro 8 was implemented on 20 intersections along the three corridors during morning

peak. The system of signalized intersections was tested using delay per vehicle, 95th percentile

queue length of the critical left turn movement, v/c, and ICU to evaluate pattern 1 signal timing

performance as shown in appendix (D).


Signal timing Pattern 2 during AM peak is the current signal timing implemented on SR 50,

SR 535, and SR 536 signalized intersections. Actually, the current signal timing was recently

approved by the (FDOT) and performed on a number of corridors in Florida. The signal retiming

system extended moderately the signal cycles length of intersections corridors.


The cycle lengths of pattern 2 signalized intersections show longer cycles length with usually

between 5 to 10 more seconds comparing with pattern 1 that led to increase in the delay of traffic

33

passing through the corridors intersections. Therefore Synchro 8 software was utilized on 20

intersections located on SR 50, SR 535, and SR 536 corridor during morning peak. It examined

the pattern 2 signal timing all along the corridors. The system of signalized intersections were

tested using delay per vehicle, 95th percentile queue length of critical left turn movement, v/c ratio,

and ICU factors to evaluate signal timing pattern 2 performance. Appendices (C) and (D) provide

traffic characteristics and efficiency measurements of the signal timing pattern 2 of the studied

signalized intersections during AM peak.


Signal timing pattern 3 during AM peak is a proposed signal timing of PRT of 2 seconds.

Theoretically, the proposed signal timing was adopted in this research to predict the performance

and safety risks of the signalized intersection network along the three corridors. The proposed

signal timing has the same criteria of pattern 2. However, it has longer PRT that causes longer

cycle length. Appendix (C) shows the proposed characteristics and cycle lengths of the studied

system.


The cycle lengths of pattern 3 signalized intersections show longer cycles length with usually

3 more seconds comparing to pattern 2. Pattern 3 signal timing composes of PRT of 2 seconds and

clearance interval as same as pattern 2. The signal timing pattern 3 system on signalized

intersections along SR 50, SR 535, and SR 536 was tested using delay per vehicle, 95th percentile

queue length of critical left turn movement, intersection v/c, and ICU factors to evaluate the signal

timing performance using such a proposed signal timing, see appendix (D).

34

4.1.4 Signal Timing Patterns Evaluation

The main purpose of signal retiming effort performed by (FDOT) is to minimize the RRL

frequencies and improve the level of safety for such signalized intersections. However, potential

issues is considered to be obvious of extending the change and clearance intervals. The three

patters of signal timing are tested using proper traffic measurements to evaluate each pattern and

how it vary from the base signal timing (pattern 1). Additionally, list of graphs are illustrated to

complete the picture of analysis.

1. The estimated Delay per vehicle for Signal Timing Patterns

The overall intersection delay was used to evaluate each signal timing patterns based on the

synchro 8 simulation of the signalized intersections along the three corridors, see Tables(8) and

Table(9).

I. SR 50 estimated Delay for the Signal Timing patterns

Table 8: SR 50 estimated Delay for the Signal Timing patterns

AM Plan Intersection Delay Del/veh (s)

Intersection No. Pattern 1 Pattern 2 Pattern 3

Intersection 1 14.9 16.5 18.5


Intersection 3 42.3 49 48.6




Intersection 7 46.6 56.6 54




Average 33.97 42.06 44.03

It can be observed from figure (7) that the overall trend of delay increases from Pattern 1 to

Pattern 2 and pattern 3. However, the delay is more significant from pattern 1 to pattern 2 and

35

pattern 3 while the delay is slightly reasonable from pattern 2 to pattern 3. The cause is that the

pattern 2 and pattern 3 have the same clearance interval duration while pattern 1 has lower

clearance interval duration comparing with pattern 2 and pattern 3. Furthermore, the pattern 3

which has a longer PRT of two seconds and longer cycle length has some intersections with lower

delay comparing with pattern 2. The explanation of decreasing delay at certain intersections with

longer PRT and cycle length is that certain approaches of those intersections have high level of

volume and limited green intervals. Therefore, a longer PRT of change interval is considered as a

part of green interval by synchro 8 that leaded to discharge more traffic and minimized the overall

delay, like Intersections 3, 5, and 7.

Figure 7: SR 50 Estimated Delay for the Signal Timing patterns

II. SR 535 and SR 536 estimated Delay for the Signal Timing patterns

0

10

20

30

40

50

60

70

80

0 2 4 6 8 10 12

SR 50 ARTERIAL ESTIMATED DELAY

Pattern 1 Pattern 2 Pattern 3

36

Table 9: SR 535 and SR 536 estimated Delay for the Signal Timing patterns

AM Plan Intersection Delay Del/veh (s)


Intersection 11 173.1 175.6 174.6


Intersection 13 72 97.9 113.1



Intersection 16 127.4 118.5 112.7





Average 62.44 70.17 73.19

Figure (8) shows an increases of overall delay from Pattern 1 to Pattern 2 and pattern

3 for signalized intersections located on SR 535 and SR 536 during morning peak period. The

Intersection delay is seen more significant from pattern 1 to pattern 2 or pattern 1 to pattern 3 while

the delay is considered slight from pattern 2 to pattern 3. The cause is that the pattern 2 and pattern

3 have the same clearance interval duration while pattern 1 has lower clearance interval duration

comparing with pattern 2 and pattern 3. Furthermore, pattern 3 which has longer cycle length

includes intersections with a lower delay. The explanation of decreasing delay in certain

intersections within a longer PRT is that certain approaches of those particular intersections have

a high level of volume and limited green intervals. Therefore, synchro 8 considers the longer PRT

of change interval as a part of green interval that leads to discharge more traffic and minimize the

overall delay, like Intersections 11, 14, 16 and 19.

2. The Estimated 95th Percentile queue length for Signal Timing Patterns

Queue length can evaluate properly the functionality of such signalized intersections.

Therefore, the queue length of left turn movement was adopted on 20 signalized intersection to

investigate the effectiveness of extending the change and clearance intervals on the studied

37

framework. In fact the left turn movement signal timing was deeply investigated by the FDOT

traffic engineers to minimize the risk of RLR. As a result, the left turn movement clearance interval

provides longer clearance interval comparing to through movement. The FDOT traffic engineers

adopted 25 mph instead of post speed to estimate the clearance interval of left turn phases.

In this study, the 95th percentile queue length of the critical left turn movement of such

intersection will be investigated using the three signal timings during AM peak plan. See Tables

(10) and Table (11).

Figure 8: SR 535 and SR 536 estimated Delay for the Signal Timing patterns

I. SR 50 95% Percentile Queue length for the Signal Timing patterns

The trend shown in Figure (9) reflects an increase of queue length as the change and

clearance intervals duration increases. The majority of SR 50 corridor signalized intersections

provide longer queue length seen in pattern 2 and pattern 3 comparing with signal timing

pattern 1. The average 95th percentile for pattern signal timing 3 is counted lower than the

0

20

40

60

80

100

120

140

160

180

200

0 2 4 6 8 10 12

SR 535 & 536 TOTAL DELAY


38

average 95th percentile for signal timing pattern 2. Pattern 3 has several intersections that

appeared to benefit of extending the change interval during AM peak period. Therefore,

Synchro 8 considered a PRT of 2 second a benefit to minimize the queueing length of those

critical intersections having higher volume and limited green intervals.

Table 10: SR 50 95% Percentile Queue length for the Signal Timing patterns

AM Plan 95th Percentile Queue length (ft)


Intersection 1 129 130 135.5

Intersection 2 254 291 271









Average 155.6 186 163.05

II. SR 535 and SR 536 95% Percentile Queue length for the Signal Timing patterns

SR 535 and SR 536 are found to follow the natural correlation between cycle’s length and 95%

percentile queuing length. Most signalized intersections along SR 535 and SR 536 have longer

queue length as the change and clearance intervals duration increases. The average 95th percentile

queue length for Pattern 2 and pattern 3 signal timing are considered significantly high comparing

with pattern 1during AM peak period. Pattern 2 and 3 show similarity in the average intersection

queue length, see figure (10). However, a number of signalized intersections for pattern 3 signal

timing are dramatically greater than the same intersections in pattern 2 signal timing during the

peak morning period.

39

Table 11: SR 535 and SR 536 95% Percentile Queue length for the Signal Timing patterns

AM Plan 95th Percentile Queue length (ft)












Average 300.7 318.1 318.4

Figure 9: SR 50 95% Percentile Queue length for the Signal Timing patterns

3. Intersection V/C Ratio for Signal Timing Patterns

Intersection v/c ratio is used as a traffic factor to evaluate the three signal timing patterns.

The relationship between the intersection delay and v/c ratio is considered positive. As a result,

0

100

200

300

400

500

600

700

0 2 4 6 8 10 12

SR 50 95% PERCENTILE QUEUE LENGTH

Before 95th queue (ft) current 95th queue (ft) Proposed 95th queue (ft)

40

v/c ratio is predicted higher as the intersection delay increases. To summarize, extending the

change and clearance intervals is found to increase the intersection overall delay, queue length and

v/c ratio.

I. SR 50 V/C Ratio for the Signal Timing patterns

Table (12) shows the intersection v/c ratio for signalized intersection located on SR 50

during AM peak period for various signal timings.

Table 12: SR 50 V/C Ratio for the Signal Timing patterns

AM Plan Intersection V/C Ratio












Average 0.59 0.61 0.62

Figure 10: SR 535 and SR 536 95% Percentile Queue length for the Signal Timing patterns

0

200

400

600

800

0 2 4 6 8 10 12

SR 535 AND SR 536 95% PERCENTILE QUEUE LENGTH

Before 95th queue (ft) current 95th queue (ft) Proposed 95th queue (ft)

41

II. SR 535 and SR 536 V/C Ratio for the Signal Timing patterns

Table (13) shows the intersection v/c Ratio for the signalized intersections located on

SR535 and SR 536 arterials during AM peak period for the three various signal timings.

Table 13: SR 535 and SR 536 V/C Ratio for the Signal Timing patterns

AM Plan Intersection V/C Ratio












Average 0.65 0.69 0.70

The different signal timing patterns of SR 50, 535, and SR 536 show the expected trend,

see figure (11) and (12). Pattern 2 and 3 illustrate logical increase in v/c ratio that maintain the

same trend of previous traffic measurements. Pattern 2 and 3 show 3-5% increase of v/c rate since

signal timing pattern 2 and 3 have longer cycle length that led to longer traffic delay, see figures

(11)and (12).

4. Intersection Capacity Utilization ICU for Signal Timing Patterns

Intersection Capacity Utilization ICU is a method for measuring a roadway intersection's

capacity. It is an ideal technique for transportation planning system such as roadway design,

congestion management studies and traffic impact projects. ICU is also defined as "the sum of

the ratios of approach volume divided by approach capacity for each leg of intersection which

42

controls overall traffic signal timing plus an allowance for clearance times.(Crommelin, 1974)"

The ICU can measure how much reserve capacity is available or how congested the intersection

is. The ICU is hired in this study to investigate the three signal timing along three corridors

during AM peak plan.

Figure 11: SR 50 V/C Rate for the Signal Timing patterns

I. SR 50 Intersection Capacity Utilization ICU for the Signal Timing patterns

Table (14) shows ICU for signalized intersections located on SR 50 during AM peak period

for the studied signal timing patterns.

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

0 2 4 6 8 10 12

SR 50 V/C RATIO

Pattern1 Pattern2 Pattern 3

43

Table 14: SR 50 Intersection Capacity Utilization ICU for Signal Timing Patterns

AM Plan Intersection Capacity Utilization ICU












Average 66.67 69.30 71.03

Figure 12: SR 535 and SR 536 V/C Ratio for the Signal Timing patterns

II. SR 535 and SR 536 Intersection Capacity Utilization ICU for the Signal Timing patterns

Table (15) illustrates ICU for signalized intersections located on SR 535 and SR 536 during

AM peak period for the signal timing patterns.

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 5 10 15 20 25

SR 535 & SR 536 V/C RATIO


44

Table 15: SR 535 and SR 536 SR ICU for Signal Timing Patterns

AM Plan Intersection Capacity Utilization ICU









Intersection 18 49.5 52 53



Average 69.32 73.47 74.73

The various signal timing patterns implemented on the signalized intersections located on

the SR 50, SR 535, and SR 536 provide ideal ICU reads during AM peak plan. The signal timing

patterns state clear increase in the average ICU of the studied signalized intersection that was

caused by the additional change and clearance intervals. Figures (13) and (14) support that signal

timing pattern 2 and 3 have greater ICU comparing with signal timing pattern 1along the studied

signalized intersections during AM peak plan.

Figure 13: SR 50 Intersection Capacity Utilization ICU

0.00

20.00

40.00

60.00

80.00

100.00

0 2 4 6 8 10 12

SR 50 Intersect ion Capaci ty Utl izat ion ICU


45

4.1.5 Signal Timing Patterns Impact on a Corridor

1. Total Arterial Delay per vehicle

Table (16), shows the total delay per vehicle estimated for a vehicle traveling through a

number of signalized intersections that works on such a certain signal timing system.

Table 16: Arterials Total Delay per vehicle

AM Plan Total Delay Del/veh. (s)

Arterial Approach Pattern 1 Pattern 2 Pattern 3

EB SR 50 310.9 393.9 384

WB SR 536 82.0 124.8 113.2

SB SR 535 478.6 518.9 564.1

2. Total Travel Time on a Corridor

The travel time spent on a corridor is an essential measurement that evaluate signal timing

pattern system and its potential delay on signalized intersections, see Table (17).

Table 17: Arterials Total Travel Time

AM Plan Traveled Time (s)


EB SR 50 629.6 707.9 704.2

WB SR 536 188.2 228.5 220.5

NB SR 535 1946 1773.7 2108.3

Three different corridors are simulated in this study to evaluate the delay and predicted

traveled time using three different signal timing. It obviously observed that the additional time

of change and clearance intervals clearly affected the arterial’s efficiency. From Table (14) and

Table (15), signal timing pattern 1 provides lower delay and traveled time through the

corridors. In contrast, the pattern 2 and 3 signal timing indicate longer delay and traveled time

because of the addition of amber and clearance intervals.

46

Figure 14: SR 535 & SR 536 Intersection Capacity Utilization ICU

4.2 Midday Signal Timing Plan

A list of tables and graphs are illustrated to show the delay, 95% percentile queueing length

of critical left turn movement, and v/c ratio factors of signal timing pattern 1, 2 and 3 for the

signalized intersections along three corridors during midday plan.


Traffic simulation was performed on the three corridors signalized intersections during midday

period. Firstly, pattern1 signal timing was simulated during this period using the signalized

intersections features such as cycle length, volume and split phasing, see appendix (C).


Signal timing pattern 1 implemented on the signalized intersections located on SR 50, SR 535,

and SR 536 corridors was examined during midday period. The system of signalized intersections

0

10

20

30

40

50

60

70

80

90

100

0 5 10 15 20 25

SR 535 & SR 536 Intersect ion Capaci ty Utl izat ion ICU


47

was tested using delay per vehicle, 95th percentile queue length of critical left turn movement, v/c

ratio, and ICU factors to evaluate the signal timing pattern 1 performance during midday plan see

appendix (D).


Signal timing pattern 2 during midday period was involved to simulate the current signal

timing on SR 50, SR 535, and SR 536 signalized intersections. The signal retiming system has

longer change and clearance that increased the intersections cycle’s length. Appendix (c) shows

the signal timing pattern 2 characteristics of the studied signalized intersections along the studied

corridors.


The current signal timing of SR 50, SR 535, and SR 536 signalized intersections was examined

using Synchro 8 along during midday period. Three traffic performance measurements were

conducted using pattern 2 signal timing to evaluate the performance efficiency of the intersections,

see appendix (D).


The proposed signal timing was performed in this research using change interval with a PRT

of two seconds during midday period. It is performed to predict the performance and safety of the

studied signalized intersections network along the three corridors. The proposed signal timing has

the same criteria of pattern 2 signal timing. However, longer PRT causes a longer cycle length.

See appendix (C) for more details about signal timing pattern 3 characteristic and signalized

intersections features during midday plan.

48

4.2.3.1 Arterial Intersections Characteristics and Efficiency Measurements

The simulation was performed using pattern 3 signal timing during midday period. 20

intersections along three corridors were simulated using the same characteristics of intersections.

Appendix (D) provides the overall functionality of signal timing pattern 3 on the studied signalized

intersections during midday plan.


It is clearly seen that increasing the change and clearance intervals caused potential issues

during midday period. The three patters of signal timing were tested using proper factors of

analysis to evaluate each signal timing pattern. Lists of quantitative results and graphs are

illustrated to judge the three signal timing systems.

1. The estimated Delay per vehicle for Signal Timing Patterns

Total intersection delay per vehicle was adopted using the synchro 8 simulation to investigate

how suitable the signal timing systems are, see Tables (18) and Table (19).



Midday Plan Intersection Delay Del/veh (s)












Average 34.67 37.02 39.96

49

The overall average delay shows an increases as the cycle length increases, see figure (15). It

is observed that the delay of pattern 2 and pattern 3 are moderately greater than pattern 1.

Additionally, it is observed that the PRT of 1.5 and 2 seconds fairly increased the delay of the

signalized intersections. However, a number of approaches in signal timing pattern 2 and pattern

3 show lower overall intersection delay even the change and clearance intervals are extended. The

explanation of decreasing delay in a certain intersections within longer PRT and cycle length is

that certain approaches have high level of volume and limited green intervals. Therefore, a longer

PRT of change interval is considered as a part of green interval by synchro 8 that leaded to

discharge more traffic and minimize the overall delay, like Intersections 7, and 8 of pattern 2.

Another potential question can be risen whey the overall delay of signal timing pattern 2

implemented on intersection 7 does not follow the trend. NBL during midday period is a critical

case and saturated by traffic. Therefore, an increasing of certain time for change may relive the

congestion while prolonging the change interval over the limit using a PRT of 2 second caused

overall delay for the entire intersection.

II. SR 535 and SR 536 Estimated Delay for Signal Timing patterns

Table 19: SR 535 and SR 536 Estimated Delay for Signal Timing patterns

Midday Plan Intersection Delay Del/veh (s)


Intersection 11 123.6 118.5 132.4


Intersection 13 46 59.1 62








Average 39.17 41.99 44.35

50

SR 535 and SR 536 almost have the same phenomenon as SR 50. The two corridors

show an increases of overall delay from Pattern 1 to Pattern 2 and pattern 3, see figure (16).

Furthermore, pattern 3 which has longer cycle length includes intersections with a lower delay

which is explained recently.

2. The Estimated 95th Percentile queue length for Signal Timing Patterns


Therefore, queue length factor of the critical left turn movement of such intersection was

performed on 20 signalized intersection to investigate the effectiveness of the tree signal timing,

see Table (20) and Table (21).

Figure 15: SR 50 estimated Delay for the Signal Timing patterns

0

20

40

60

80

100

120

0 2 4 6 8 10 12

SR 50 ESTIMATED DELAYESTIMATED DELAY


51


Table 20: SR 50 95% Percentile Queue length for the Signal Timing patterns

Midday Plan 95th Percentile Queue length (ft)












Average 187.2 203.3 201.7

It can be observed from Figure (17) that the trend of 95% percentile queue length increases

as the change and clearance intervals duration increases. 95% percentile Queue length of signal

timing pattern 2 and pattern 3 are considered significantly high comparing with pattern 1. Some

potential signs appear in the trend such as the dropping queue length in pattern 3 comparing with

pattern 2. The queue length criteria almost follow the delay factor characteristic so Synchro 8

considered the extension of change interval in certain time relieve the congestion in a particular

approach which affects the overall queueing length.


SR 535 and SR 536 support the natural association between cycle’s length and the queuing

length. The trend of queuing increases as the change and clearance intervals duration increase, see

figure (18). Queueing length of Pattern 2 and pattern 3 signal timing are considered significantly

higher comparing with pattern 1. However, the average 95th percentile queue length of pattern 3

52

seems to be lower than the average 95th queue length of pattern 2. In pattern 3 signal timing, the

critical approach of intersection 14 benefited from extending the change interval for that approach

which discharge higher volume and minimize the overall 95th percentile queue length.

Table 21: SR 535 and SR 536 Queue length for the Signal Timing patterns

Midday Plan 95th Percentile Queue length (ft)

intersection No. Pattern 1 Pattern 2 Pattern 3











Average 320.4 348.7 334.3

Figure 16: SR 535 and SR 536 Estimated Delay for Signal Timing patterns

3. Intersection V/C ratio for Signal Timing Patterns

0

50

100

150

0 2 4 6 8 10 12

SR 535 AND SR 536 ESTIMATED DELAY


53

V/C ratio is used with other traffic measurements to distinguish between the different signal

timing systems. In conclusion, it is observed that extending the change and clearance

intervals increases the intersection volume to capacity ratio.

I. SR 50 V/C rate for the Signal Timing patterns

Table (22) shows the intersection v/c ratio for the signalized intersections located on SR

50 during midday period during three signal timings.

Table 22: SR 50 V/C rate for the Signal Timing patterns

Midday Plan Intersection V/C rate












Average 0.521 0.541 0.548

SR 50 signalized intersections during midday period provides an expected trend. The

average v/c ratio of the three signal timing gets larger as the cycle length becomes longer, see

figure (19). It is shown that the average v/c ratio of signal timing pattern 2 and pattern 3 is greater

than the average of signal timing pattern 1.

54



II. SR 535 and SR 536 V/C ratio for the Signal Timing patterns

Table (23) shows the intersection v/c ratio for the signalized intersections located on SR 535

and SR 536 arterials during midday period during three signal timings.

0

20

40

60

80

100

120

0 2 4 6 8 10 12



0

20

40

60

80

100

120

140

0 2 4 6 8 10 12

SR 535 and SR 536 95% Percentile Queue length


55

Table 23: SR 535 and SR 536 V/C rate for the Signal Timing patterns

Midday Plan Intersection V/C ratio












Average 0.559 0.586 0.594

SR 535 and SR 536 signalized intersections during midday period maintains the same

relationship between the cycle length and v/c ratio. To conclude, it is observed that the average

v/c ratio of the three signal timing gets larger as the cycle length becomes longer see figure (18).

Figure 19: SR 50 V/C rate for the Signal Timing patterns

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0 2 4 6 8 10 12

SR 50 V/C RATIO


56


The ICU is used in this study for the investigation of the three signal timing along three

corridors during Midday plan. It is considered an ideal tool investigating the impact of

additional change and clearance intervals on signalized intersection performance. Three signal

timing patterns along three corridors are going to be investigated using such a proper

measurement seen in table (24) and (25).


Table (24) shows ICU for signalized intersections located on SR 50 during midday plan

for various signal timings.

Table 24: SR 50 ICU for Signal Timing Patterns

Midday Plan Intersection Capacity Utilization ICU












Average 60.43 64.35 66.23


Table (25) illustrates ICU for signalized intersections located on SR 535 and SR 536 during

Midday period for various signal timings.

57


Midday Plan Intersection Capacity Utilization ICU












Average 60.73 65.16 66.59

The various signal timing patterns implemented on the signalized intersections located on

the SR 50, SR 535, and SR 536 provide ideal ICU reads during Midday plan. The overall ICU

average of signal timing patterns seems to be greater as the cycle length becomes longer. Figures

(21) and (22) show that signal timing pattern 2 and 3 have higher ICU comparing with signal

timing pattern 1along the studied signalized intersections.

Figure 20: SR 535 and SR 536 V/C rate for the Signal Timing patterns

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0 5 10 15 20 25



58


1. Arterial Total Delay per vehicle

Total delay per vehicle is a parameter estimating the delay for a vehicle traveling through

a number of signalized intersections that works on such a certain signal timing system, see

Table (26).

Table 26: Arterial Total Delay per vehicle

Midday Plan Total Delay Del/veh. (s)


EB SR 50 332.5 363.9 387.6

WB SR 536 86.5 96.4 91.5

NB SR 535 234.8 247.8 287.8


The travel time spent on a corridor is an essential measure that evaluate how long the

signal timing pattern may cause delay, see Table (27).

Figure 21: SR 50 ICU for Signal Timing Patterns

0

10

20

30

40

50

60

70

80

90

0 2 4 6 8 10 12

SR 50 ICU For Signal Timing Pat terns


59

Table 27: Arterial Total Travel Time

Midday Plan Traveled Time (s)


EB SR 50 641.1 672.2 696.2

WB SR 536 176.8 184.1 179.5

NB SR 535 421.8 433.3 474.0

Total delay and traveled time factors during midday plan are performed to evaluate the

three signal timings during PM plan. The simulation of signalized intersections along the three

corridors provided significant delay and longer traveled time using pattern 2 and pattern 3 signal

timing. 3-10 % additional delay and longer travel time is obtained on the arterials using signal

timing 2 and 3.

Figure 22: SR 535 & SR 536 ICU for Signal Timing Patterns

0

10

20

30

40

50

60

70

80

90

0 5 10 15 20 25

SR 535 & SR 536 ICU For Signal Timing Pat terns


60

4.3 PM Signal Timing Plan

A list of tables and graphs are provided to evaluate the intersection delay, v/c ratio, ICU,

and queueing length of signal timing pattern 1, 2 and 3 for the signalized intersections along three

corridors during evening peak plan.


Synchro 8 simulation was conducted to test the signal timing pattern 1 for a number of

signalized intersections during PM peak plan. Pattern1 signal timing was simulated during this

period using the signalized intersections features such as cycle length, volume and split phasing,

see appendix (C).


Signal timing Pattern 1 of signalized intersections along the studied corridors was simulated

during PM period. The intersection delay per vehicle, 95th percentile queue length of the critical

left turn movement, v/c, and ICU factors were conducted to evaluate the before signal timing

performance during PM peak plan see appendix (D).


Signal timing of SR 50, SR 535, and SR 536 signalized intersections were simulated using

Synchro 8. As known, the signal retiming system has longer change and clearance intervals that

increased the intersections cycle’s length. Appendix (C) shows the intersections characteristics and

cycle lengths of the three corridors signalized intersections.

61


The current signal timing during PM peak plan was simulated using Synchro 8 along 20

signalized intersections of the studied corridors. Three traffic performance measurements were

conducted using pattern 2 signal timing to evaluate the efficiency of the intersections traffic

performance during PM peak plan, see appendix (D).


The proposed signal timing was performed in this research using change interval with a PRT

of two seconds during PM peak period. It was performed to predict the smooth of traffic and safety

for the signalized intersections network along the three corridors if a PRT of 2 seconds is adopted.

The proposed signal timing has the same criteria of pattern 2 signal timing. However, the longer

PRT causes a longer cycle length. Appendix (C) shows the proposed characteristics and cycle

lengths of the studied signalized intersections.


Synchro 8 was conducted using pattern 3 signal timing during PM peak period. Twenty

intersections along SR 50, SR 535, and SR 536 were simulated using the same characteristics of

intersections. Appendix (D) shows the overall functionality of the signalized intersections during

the PM peak plan


It is clearly seen that increasing the change and clearance intervals caused potential issues

during evening peak period. The three patters of signal timing are tested using proper factors of

62

analysis to evaluate each pattern of signal timing. Lists of quantitative results and graphs are

illustrated to judge the three systems of signal timing.

1. The estimated Intersection Delay per vehicle for Signal Timing Patterns

Total intersection delay per vehicle was estimated using the synchro 8 simulation to investigate

the three patterns of signal timing during PM peak, see Tables (28) and Table (29).



PM Plan Intersection Delay Del/veh (s)












Average 42.21 46.06 50.07

The overall trend of delay increases from Pattern 1 to Pattern 2 and pattern 3, see Figure (23).

Also, the intersection delay of pattern 2 to pattern 3 signal significantly increased. To sum up,

adopting a PRT of two seconds fairly increased the delay of signalized intersections during PM

peak period. Furthermore, a number of approaches in pattern 2 and pattern 3 signal timing show

lower overall intersection delay even the change and clearance intervals are extended. Actually,

Synchro 8 considers the change interval as a part of green, so extending the change interval led

63

certain approaches of particular intersections having high level of volume and limited green

intervals to discharge more traffic and minimize the overall delay.

Figure 23: SR 50 estimated Delay for the Signal Timing patterns

II. SR 535 and SR 536 Estimated Delay for Signal Timing patterns

Table 29: SR 535 and SR 536 Estimated Delay for Signal Timing patterns

PM Plan Intersection Delay Del/veh (s)


Intersection 11 322.4 347.1 307.9


Intersection 13 62.8 105.6 114.2

Intersection 14 111.8 119.2 111.4

Intersection 15 166 169.7 175.6

Intersection 16 160.1 169.1 190.5


Intersection 18 39 15.8 13

Intersection 19 110.2 113 116.7


Average 107.15 115.09 115.7

0

10

20

30

40

50

60

70

80

90

0 2 4 6 8 10 12

SR 50 ESTIMATED DELAY


64

The overall trend of the intersection delay increased from Pattern 1 to Pattern 2 and

pattern 3 during PM period along the studied SR 535 and SR 536 signalized intersections, see

Figure (24). The results does not demonstrate a significant change from pattern 2 to pattern 3

during PM peak period for SR 535 and SR 536 signalized intersections. Several critical

intersections benefit of extending the change interval even though the cycle length became

longer.

2. The Estimated 95th Percentile queue length (ft) for Signal Timing Patterns


Therefore, 95% percentile queue length of the critical left turn movement was performed on 20

signalized intersection to investigate the performance of the tree signal timings, see Table (30) and

Table (31).


Table 30: SR 50 Queue length for the Signal Timing patterns

PM Plan 95th Percentile Queue length (ft)












Average 254.7 275.5 326.3

65

It can be observed from figure (25) that the trend of queuing length increases as the change

and clearance intervals duration increases during evening peak period. Queueing length of signal

timing pattern 2 and pattern 3 are considered significantly high comparing with pattern 1.

Additionally, it observed that the queueing length of pattern 3 signal timing is greatly higher than

pattern 2.

Figure 24: SR 535 and SR 536 Estimated Delay for Signal Timing patterns


SR 535 and SR 536 support the natural association between the cycle’s length and queuing

length. The trend of queuing length increases as the change and clearance intervals duration

increases, see figure (26). Queueing length of Pattern 2 and pattern 3 signal timing are considered

significantly higher comparing with pattern 1. However, the average 95th percentile queue length

seems to be lower than the average 95th queue length for pattern 2. Signal timing pattern 3 is

-50

0

50

100

150

200

250

300

350

400

0 2 4 6 8 10 12

SR 535 AND SR 536 ESTIMATED DELAY


66

influenced by WBL of intersection 18 that benefited of extending the change phase which lead to

discharge higher volume and minimize the overall 95th percentile queue length.

Table 31: SR 535 and SR 536 Queue length for the Signal Timing patterns

PM Plan 95th Percentile Queue length (ft)












Average 472.5 508.6 495.4


0

100

200

300

400

500

600

0 2 4 6 8 10 12



67

3. Intersection V/C Ratio for Signal Timing Patterns

Intersection v/c ratio is used as a traffic factor to evaluate the three signal timing patterns. To

summarize, extending the change and clearance intervals is found to increase the intersection

overall v/c ratio.

I. SR 50 V/C Ratio for the Signal Timing patterns

Table (32) shows the intersection v/c ratio for the studied signalized intersections located

on SR 50 during PM peak period for various signal timings.

Table 32: SR 50 V/C Ratio percentages for the Signal Timing patterns

PM Plan Intersection V/C Ratio












Average 0.68 0.701 0.708

The averages v/c ratio for SR 50 signalized intersections during evening peak shows logical

changes from signal timing pattern1 to signal timing pattern 2 and 3. It is seen that both signal

timing 2 and 3 clearly provides an increase in v/c ratio. The longer cycle length caused by

additional amber and clearance intervals affected the efficiency of the signalized intersections and

cause reduction in the intersection capacity that led to an increase of v/c ratio of all intersections

see figure (27).

68


Figure 27: SR 50 V/C Ratio for the Signal Timing patterns

0

200

400

600

800

1000

1200

0 2 4 6 8 10 12

SR 535 AND SR 536 95% PERCENTILE QUEUE LENGTH


0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 2 4 6 8 10 12

SR 50 V/C RATIO


69

II. SR 535 and SR 536 V/C Ratio for the Signal Timing patterns

Table (33) illustrates the intersection v/c ratio for the studied signalized intersection located on

SR 535 and SR 536 arterials during PM peak period for the various signal timings.

Table 33: SR 535 and SR 536 V/C Ratio for the Signal Timing patterns

PM Plan Intersection V/C Ratio












Average 0.832 0.874 0.886

SR 535 and SR 536 signalized intersections during PM peak maintain the expected increase

trend of v/c ratio. Signal timing pattern 2 and 3 for all signalized intersections show clear increase

in the v/c ratio caused by the additional change and clearance intervals see figure (28).

Figure 28: SR 535 and SR 536 V/C Ratio for the Signal Timing patterns

0

0.5

1

1.5

2

0 5 10 15 20 25



70


ICU is a measurement tool used in this study to investigate the three signal timing along

three corridors during PM peak plan. Three signal timing patterns along three corridors were

investigated to study the impact of additional change and clearance intervals on the signalized

intersection performance, see Tables (34) and (35).


Table (34) shows ICU for signalized intersections located on SR 50 during PM peak plan

for the signal timings patterns.

Table 34: SR 50 ICU for Signal Timing Patterns

PM Plan Intersection Capacity Utilization ICU












Average 73.79 77.75 79.57


Table (35) illustrates ICU for signalized intersection located on SR 535 and SR 536 during

PM peak period for the studied signal timing patterns.

71


PM Plan Intersection Capacity Utilization ICU


Intersection 11 109.3 117.3 118.8



Intersection 14 120.3 123.4 124.4







Average 81.6 86.26 87.7

The three signal timing patterns implemented on the signalized intersections located on the

SR 50, SR 535, and SR 536 provide ideal ICU reads during PM peak plan. The signal timing

patterns state clear increase in the average ICU of the studied signalized intersection that was

caused by the additional change and clearance intervals. The longer cycle length implemented on

the signal timing patterns 2 and 3 led the signalized intersections to have more ICU, see Figures

(29) and (30).

Figure 29: SR 50 ICU for Signal Timing Patterns

0

20

40

60

80

100

120

0 2 4 6 8 10 12

SR 50 ICU for Signal Timing Pat terns


72


1. Total Arterial Delay per vehicle

Total delay per vehicle is a parameter estimating the delay for a vehicle traveling through a

number of signalized intersections that works on such a certain signal timing system. Table (36)

illustrates the potential delay of traffic traveling on the studied three corridors’ signalized

intersections.

Table 36: Total Arterial Delay per vehicle

PM Plan Total Delay Del/veh. (s)


WB SR 50 298.7 248.9 468.9

EB SR 536 704.9 722.2 752.6

SB SR 535 1453.3 1112.6 1277.1

Figure 30: SR 535 & SR 536 ICU for Signal Timing Patterns

0

20

40

60

80

100

120

140

0 5 10 15 20 25

SR 535 & SR 536 ICU or Signal Timing Pat terns


73


The travel time spent on a corridor is an essential measure that evaluate how functional a signal

timing pattern system is.

Table 37: Total Travel Time on a Corridor

PM Plan Traveled Time (s)


WB SR 50 580.2 566.4 752.7

EB SR 536 1018 996 1094.4

SB SR 535 2351 1853.5 2009.5

Table (36) and Table (37) measure the signal timing patterns and their impacts on the

corridors performance. The current and proposed signal timings show significant delay caused by

the additional change and clearance intervals along the studied arterials during PM peak plan. The

simulation of three signal timing patterns approved that the traveled time increases as the change

and clearance intervals increase. 7-30% potential delay is estimated caused by the additional

change and clearance intervals during PM peak plan.

4.4 Red Light Running RLR Statistics

Red light running is considered a dilemma issue in most metropolitan areas. The Florida

States Department of Transportation, FDOT admitted this issue and investigate it widely for

potential solutions. To mitigate this issue, the FDOT adopted the practice of prolonging the change

interval to minimize running red light. In this part of research, a naïve statistical method is

performed to investigate the potential impact of additional change interval on red light running

and if that reduce RLR. Based on limited data provided by Orange County FDOT for eight

74

approaches located in six intersections during ten months, a naïve statistical method was performed

as shown in Table (38).

Based on the naïve statistical method, it can be concluded that the new signal timing does

not significantly reduce the frequency of red light running. However, the new signal timing shows

significant increase of RRL in congested approaches see figure (31). To sum up, the limited data

is not reliable enough to state such conclusion.

Table 38: Average Monthly RED Light Running

Intersection No. Node# Before Average

Monthly RLR

After Average

Monthly RLR

1 OC01 42 72

2 OC61 52 41

3 OC49 48 64

4 OC28 118 117

5 OC63 74 73

6 OC52 73 182

7 OC33 27 20

8 OC34 144 206

4.5 Dilemma and Option Zones Implemented Study on SR 50 Intersections

In this analysis, Equation 4 and Equation 5 in section 2.6 in chapter 2 that estimate dilemma

and option zones were applied on selected signalized intersections of SR 50 for signal timing

pattern 1, pattern, and pattern 3 to evaluate the impact of the new signal timing project on

signalized intersections ‘potential safety risk. The calculated dilemma and option zone results are

provided in Table (33) and Appendix (E).

75

Table 39: Dilemma and Option Zones Identification of Intersection 2

intersection 2 EBL WB SBL NB WBL EB NBL SB

XC (ft) 284.9 284.9 284.9 284.9 284.9 284.9 284.9 284.9

X0 Pattern 1 (ft) 243.9 243.9 209.9 209.9 227.9 227.9 207.9 207.9

XC-X0 Pattern 1 41.0 41.0 75.0 75.0 57.0 57.0 77.0 77.0

X0 pattern 2 (ft) 274.7 274.7 261.8 261.8 258.7 258.7 259.8 259.8

XC-X0 Pattern2 10.2 10.2 23.2 23.2 26.2 26.2 25.2 25.2

X0 pattern 3 (ft) 350.1 350.1 316.1 316.1 334.1 334.1 314.1 314.1

XC-X0 Pattern 3 -65.1 -65.1 -31.1 -31.1 -49.1 -49.1 -29.1 -29.1

Using equations 4 and 5, XC and X0 were estimated for all signal timing patterns of

Intersection 1-5. In results, the new signal timing (pattern 2) provides interesting points. The

dilemma zone in all approaches are reduced to tight zones while in the other approaches, the option

zone are extended. In contrast, the signal timing pattern 3 has mitigated the dilemma zone to be

very short of all approaches and extended the option zone of the other approaches. To conclude,

the impact of signal timing pattern 2 on dilemma zone is significant. However, signal timing

pattern 3 has dilemma zone shorter than pattern 2 and has extended more option zones see Table

(33) and Appendix (E).

Figure 31: Average Monthly Red Light Running

0

50

100

150

200

250

0 1 2 3 4 5 6 7 8 9

RLR

Before Ave. After Ave.

76

4.6 Statistical Analysis

The paired t-test which is based on the hypothesis test of the mean differences between the

tested measurements of signal timing and are approximately normally distributed was applied. It

was used to find any significant difference between the signal timing 1 (P1) and the signal timing

2 (P2). Additionally, the hypothesis test was conducted between P1 and signal timing pattern 3

(P3). The test run based on the hypothesis of no significant differences between the mean of the

traffic measurements of signal timings. The following tables 40-45 show the summery of the paired

t-test results during three periods and only applied to the corridor level.

Table 40: SR 50 Paired t-test of signal Timing Patterns during AM Plan

AM plan 95% Confidence Interval Paired T-Test (2-tailed)

SR 50 P1 vs P2 P1 vs P3 P2 vs P3

Mean Std. Dev Sig. Mean Std. Dev Sig. Mean Std. Dev Sig.

Delay

Del/veh (s)

-8.000 7.557 .009 -10.10 7.047 .001 -2.100 5.280 .240

95th queue

length (ft)

-30.400 55.448 .117 -7.450 16.177 .179 22.950 55.146 .221

Intersection

V/C

-.02000 .008165 .00003 -.0300 .011547 .00002 -.01000 .004714 .00009

ICU

-2.6300 3.879877 .061 -4.3600 4.14224 .009 -1.7300 .471522 .001

From Table (40), it is clearly shown that there are significant differences between the three

signal timing patterns during AM plan along SR 50. Regarding to the intersection delay, the

difference appears to be significant between P1 and P3 at 95% confidence interval while the

difference between P1 and P2 is significant at 90% confidence interval. However, there is no

significant difference between the delays of P2 and P3.

77

Pared t-test does not illustrate any significant difference between the 95th queue lengths

signal timing patterns. In contrast, the paired t-test of the intersection v/c ratio and ICU obtained

significant differences between P1and P2, P1 and P3, and P2 and P3.

Table 41: SR 535&536 Paired t-test of signal Timing Patterns during AM Plan

AM plan 95% Confidence Interval Paired T-Test (2-tailed)

SR 535&

SR536

P1 vs P2 P1 vs P3 P2 vs P3

Mean Std.

Dev

Sig. Mean Std. Dev Sig. Mean Std. Dev Sig.

Delay

Del/veh (s)

-7.730 11.711 .066 -10.750 17.1036 .078 -3.020 15.729 .559

95th queue

length (ft)

-17.40 67.360 .435 -17.700 80.491 .504 -.3000 50.839 .986

Intersection

V/C

-.0370 .014944 .00003 -.0470 .0170 .00001 -.0100 .0047 .00009

ICU

-4.150- 2.84419 .001 -5.41000 3.16243 .0001 -1.260 .494862 .0001

The paired t-tests applied on SR 535 & SR 536 signal timing patterns seem to behave as

the SR 50 signal timing during AM plan. Table (41) shows different mean of intersection delay

and v/c ratio. It is clearly observed that the delay of P1 significantly differs from P2 and P3 at 90%

confidence interval while the mean of P2 and P3 does not show significant difference.

On the other hand, the paired t-test applied between P1vs P2, P1 vs P3, and P2 vs P3 at

95% percentile queue length does not show any significant difference. However, the paired t-test

of intersection v/c ratio and ICU provided significant differences among all signal timing patterns.

Table (42) illustrates the results of the paired t-test applied on three signal timings

measurements during midday plan along SR 50 arterial. It is seen that only P1 vs P3 of intersection

delay shows significant difference. Furthermore, the paired t-test conducted on the queue length

state significant differences between P1vs P2 and P1vs P3. In addition, the paired t-test of

78

intersection v/c ratio and ICU obtained significant differences between the different signal timing

patterns.

Table 42: SR 50 Paired t-test of signal Timing Patterns during Midday Plan

Mid plan 95% Confidence Interval Paired T-Test (2-tailed)



Delay

Del/veh (s)

-2.350 8.6249 .411 -5.290 5.8159 .018 -2.940 12.404 .473

95th queue

length (ft)

-16.10 21.184 0.04 -14.500 23.177 0.079 1.600 16.741 0.769

Intersection

V/C

-.0200 .0105 .00020 -.0270 .0125 .00008 -.0070 .0048 .00132

ICU

-3.920 1.157392 .0001 -5.80000 1.42127 .0001 -1.880 .391010

.0001

The 95% Confidence Interval Paired T-Test of SR 535 & SR 536 signal timing patterns

illustrates significant difference between the mean of signal timings measurements during midday

plan, see Table (43). The intersection delay provides significant difference between P1and P3. In

addition, queue length P1 significantly differs from P2. In contrast, the paired t-test of v/c ratio

and ICU show significant differences between P1 vs P2, P1 vs P3 and P2 vs P3.

Table 43: SR 535&536 Paired t-test of signal Timing Patterns during Midday Plan

Mid plan 95% Confidence Interval Paired T-Test (2-tailed)

SR 535&

SR536



Delay

Del/veh (s)

-2.820 5.024 0.11 -5.180 6.276 0.028 -2.360 5.700 0.223

95th queue

length (ft)

-28.30 26.428 0.008 -13.900 51.802 0.418 14.400 56.117 0.438

Intersection

V/C

-.0270 .0125 .00008 -.0350 .0135 .00002 -.0080 .0042 .00020

ICU

-4.430 1.828813 .0001 -5.86000 1.96140 .0001 -1.430 .356059 .0001

79

Table (44) states significant differences between the means of the signal timings different

measurements during PM plan along SR 50 corridor. It can be concluded that there are significant

differences between the intersection delay means of signal timings P1 vs P2 using 90% confidence

interval and P1 vs P3 using 95% confidence interval. Additionally, the 95% percentile queue

length shows significant differences between signal timings P1 vs P3 and P2 vs P3. Furthermore,

the intersection v/c ratio and ICU show significant differences between all the signal timing

patterns.

Table 44: SR 50 Paired t-test of signal Timing Patterns during PM Plan

PM plan 95% Confidence Interval Paired T-Test (2-tailed)



Delay

Del/veh (s)

-3.850 5.830 0.066 -7.860 10.139 0.037 -4.010 7.998 0.147

95th queue

length (ft)

-

20.800

39.395 0.129 -71.600 79.787 0.019 -50.80 74.601 0.06

Intersection

V/C

-.0210 .0088 .00003 -.0280 .0092 .000005 -.0070 .0048 .001

ICU

-3.960 1.373722 .0001 -5.78000 1.55406 .0001 -1.820 .352136 .0001

Table (45) obtains that there are no significant differences between the traffic

measurements P1vs P2, P1 vs P3, and P2 vs P3 for intersection delay and 95th queue length during

PM plan along SR 535&SR536. However, the intersection v/c ratio and ICU show significant

differences between all signal timing patterns.

80

Table 45: SR 535&536 Paired t-test of signal Timing Patterns during PM Plan

PM plan 95% Confidence Interval Paired T-Test (2-tailed)

SR 535&

SR536



Delay

Del/veh (s)

-7.940 20.972 0.262 -8.550 27.939 0.358 -0.610 16.873 0.911

95th queue

length (ft)

-36.100 85.386 0.214 -22.900 96.799 0.473 13.200 33.918 0.25

Intersection

V/C

-.0420 .0210 .0001 -.0540 .0246 .0001 -.0120 .0063 .0002

ICU

-4.6600 1.862018 .0001 -6.1000 2.0838 .0001

-1.440 .350238 .0001

81

CHAPTER 5: CONCLUSIONS AND FINDINGS AND

RECOMMENDATIONS

5.1 Conclusions and Findings

The Florida State Department of Transportation (FDOT) has adopted a signal retiming

effort on a number of signalized intersections along several arterials. The effort of new signal

timing was based on the ITE equations. However, to minimize the RLR, the change and clearance

intervals were lengthened. This research was dedicated to investigate the impact of extending the

change and clearance intervals on the signalized intersections and the network’s performance and

safety risk. The investigations were based on the signal timing pattern 1 which was compared with

signal timing pattern 2 and pattern 3. It is considered that extending the change and clearance

intervals were based on a certain technique adopted by the FDOT traffic engineers to improve the

signalized intersection’s performance.

Dilemma zone and option zones were deeply researched in this study. The signal retiming

effort was improved to address the lack of change interval that causes such potential crashes.

Researchers found that red light running frequencies have a significant correlation with signal

timing. Therefore, FDOT has adopted the signal retiming to mitigate the dilemma.

A number of signalized intersections along three corridors during three periods were

investigated. Synchro 8 was utilized to simulate the signalized intersections in three different

signal timing categories during three time of day plans. The simulation’s criteria was based on four

traffic parameters to evaluate each signal timing’ performance and how the signal pattern 2 and 3

differ from the base signal timing (pattern 1). Finally, the simulation traffic parameters were tested

82

using an appropriate statistical test to identify whether there are significant differences between

the signal timing patterns or not during the three time of day periods.

In conclusion, generally, intersection delay, v/c ratio, and ICU of signal timing pattern 2

and pattern 3 of signalized intersections along the three arterials were found significantly different

than pattern 1during the three time of day plans. Additionally, the 95% percentile queue length of

the critical left turn movement of pattern 2 was found significantly different than pattern 1 during

midday plan along the three corridors while pattern 3 was found significantly different than pattern

1 along SR 50 at 90% confidence interval during midday and PM periods only. However, the

deference between P2 and P3 was found significant different only in the v/c ratio and ICU of

signalized intersections along the three corridors during the three time of day plans. To sum up,

the addition of change and clearance intervals of P2 caused more intersection delay by (6% to

24%) comparing with P1. However, increasing the PRT by 100% in P3 that increased the change

interval by (20% to 35%) caused 8% to 30% more intersection delay comparing with P1 along the

corridors during three time of day plans.

Investigation’s results of signal timing impact on corridors were found significant. It was

found that prolonging the change and clearance intervals significantly increased the total delay and

traveled time along the studied corridors during the three time of day plans. Briefly, the addition

of change and clearance intervals of P2 caused 6% to 27% more arterial delay comparing with P1

along the three corridors during the three time of day plans. However, P3caused 7% to 38% more

arterial delay comparing with P1 along the three corridors during the three time of day plans.

83

As known, the main purpose of lengthening the change and clearance intervals is to

minimize the RLR. Based on the limited RLR frequencies data of such approaches on the studied

framework, it was observed that extending the change and clearance intervals did not significantly

reduce the RLR rate. However, a state of such conclusion is not appropriate at this time since the

adoption of signal retiming was recently implemented and the data was not sufficient.

The signal timing pattern 2 was investigated using (Wei, 2008) equations (4) and (5). It

was found that signal timing P2 significantly reduce the dilemma zones of signalized intersections

along the studied corridors. Signal timing P2 implemented on the studied signalized interactions

approaches were found to have shorter dilemma zones by 20 to 45 ft. comparing with pattern 1

while in some approaches the dilemma zone was totally vanished. On the other hand, the proposed

signal timing P3 was found to have 25-100 ft. option zone in most approaches.

5.2 Recommendations and Future studies

Based on the findings of this study, the following recommendations were suggested:

1. Collect more RLR data to properly judge on the new signal timing impact on safety.

2. Since the difference between the signal timing pattern 2 and pattern 3 was not found

significant and also it was found that signal timing P3 created option zones in most signalized

intersections approaches, the proposed signal timing should be implemented on an arterial and a

follow up study should be dedicated to investigate the signal timing pattern 3 impact on signalized

intersections’ safety.

84

APPENDIX [A]: SIGNAL TIMING FOR THE STUDIED SIGNALIZED

INTERSECTIONS

85

Signal Timing for SR 50 Intersected with Vizcaya Lake Road

Intersection 1 WB NB WBL EB NBL

Approach Speed 45 45 25 45 45

Before yellow 4.5 3.0 4.5 4.5 3.0

Current Yellow 5.0 3.4 5.0 4.8 3.4

propped Yellow 5.5 4 5.5 5.5 4

Before ALL-red 2.3 2.3 4.3 2.3 4.3

Current ALL-red 4.2 2.6 5.4 2.6 5.4

Signal Timing for SR 50 Intersected with Good Home Road

Intersection 2 EBL WB SBL NB WBL EB NBL SB

Approach Speed 45 45 45 45 45 45 45 45

Before yellow 4.5 4.5 4.5 4.5 4.5 4.5 4.5 4.5

Current Yellow 4.8 4.8 5.0 5.0 4.8 4.8 5.0 5.0

propped Yellow 5.5 5.5 5.5 5.5 5.5 5.5 5.5 5.5

Before ALL-red 2.6 2.6 3.3 3.3 2.9 2.9 3.4 3.4

Current ALL-red 4.6 2.9 6.0 3.7 5.2 3.3 6.0 3.8

Signal Timing for SR 50 Intersected with Apopka Vineland Road


Approach Speed 45 45 45 25 45 45 25 45

Before yellow 4.5 4.5 4.5 3 4.5 4.5 3 4.5

Current Yellow 4.8 4.8 4.8 3.4 4.8 4.8 3.4 4.8

propped Yellow 5.5 5.5 5.5 4 5.5 5.5 4 5.5

Before ALL-red 3.6 3.6 3.2 5.7 2.2 2.2 5.6 3.1

Current ALL-red 6.0 4.0 5.7 6.0 4.0 2.5 6.0 3.5

Signal Timing for SR 50 Intersected with Dorscher Road


Approach Speed 45 45 30 30 45 45 30 30

Before yellow 4.5 4.5 3.5 3.5 4.5 4.5 3.5 3.5

Current Yellow 4.8 4.8 3.7 3.7 4.8 4.8 3.7 3.7

propped Yellow 5.5 5.5 4.5 4.5 5.5 5.5 4.5 4.5

Before ALL-red 2.0 2.0 4.7 4.7 1.7 1.7 5.2 5.2

Current ALL-red 3.6 2.2 5.7 5.7 3.0 1.9 6.0 6.0

86

Signal Timing for SR 50 Intersected with Highland Lakes Center

Intersection 5 EBL WB NB WBL EB SB

Approach Speed 45 45 25 45 45 25

yellow before 4.5 4.5 3 4.5 4.5 3

Yellow After 4.8 4.8 3.5 4.8 4.8 3.5

proposed 5.5 5.5 4 5.5 5.5 4

ALL-red before 2.0 2.0 5.0 2.1 2.1 5.0

ALL-red after 3.6 2.2 6.0 3.7 2.3 6.0

Signal Timing for SR 50 Intersected with CR 435 (Hiawassee Road)


Approach Speed 45 45 45 45 45 45 45 45

Before yellow 4.5 4.5 4.5 4.5 4.5 4.5 4.5 4.5

Current Yellow 5.2 4.8 4.8 4.8 4.8 5.2 4.8 4.8

propped Yellow 5.5 5.5 5.5 5.5 5.5 5.5 5.5 5.5

Before ALL-red 2.7 2.7 3.4 3.4 2.9 2.9 3.4 3.4

Current ALL-red 4.8 3.0 6.0 3.8 5.2 3.3 6.0 3.8

Signal Timing for SR 50 Intersected with Powers Drive


Approach Speed 45 45 30 35 45 45 35 30

Before yellow 4.5 4.5 3.5 4 4.5 4.5 4 3.5

Current Yellow 4.8 4.8 3.7 4.1 4.8 4.8 4.1 4.1

propped Yellow 5.5 5.5 4.5 5 5.5 5.5 5 4.5

Before ALL-red 2.2 2.2 4.5 3.8 2.2 2.2 4.5 5.3

Current ALL-red 4.0 2.5 5.4 4.5 4.0 2.5 6.0 6.0

87

Signal Timing for SR 50 Intersected with Paul Street



Before yellow 4.5 4.5 3 4.5 4.5 3

Current Yellow 5.0 4.8 3.4 4.8 5 3.4

propped Yellow 5.5 5.5 4 5.5 5.5 4

Before ALL-red 1.5 1.5 4.5 1.5 1.5 4.5

Current ALL-red 2.6 2.0 6.0 2.7 2.0 6.0

Signal Timing for SR 50 Intersected with Hastings Street



Before yellow 4.5 4.5 3 4.5 4.5 3.5

Current Yellow 4.8 4.8 4.1 4.8 4.8 4.1

propped Yellow 5.5 5.5 4 5.5 5.5 4.5

Before ALL-red 1.8 1.8 4.5 1.1 1.1 4.5

Current ALL-red 3.3 2.1 6.0 2.0 2.0 5.4

Signal Timing for SR 50 Intersected with SR 435 (Kirkman Road)



Before yellow 4.5 4.5 4.5 4.5 4.5 3.0

Current Yellow 4.8 4.8 4.8 4.8 4.8 3.7

propped Yellow 5.5 5.5 5.5 5.5 5.5 4.0

Before ALL-red 1.4 1.4 3.3 2.0 2.0 5.6

Current ALL-red 2.6 2.0 3.7 3.7 2.3 6.0

88

Signal Timing for SR 535 Intersected with SR 536


Approach Speed 55 45 55 55 45 55 55 55

Before yellow 5.0 4.3 5.0 5.0 4.3 5.0 5.0 5.0

Current Yellow 5.5 4.8 5.6 5.6 4.8 5.5 5.6 5.6

propped Yellow 6.0 5.3 6.0 6.0 5.3 6.0 6.0 6.0

Before ALL-red 2.9 4.5 4.2 3.5 3.4 4.6 4.5 3.2

Current ALL-red 6.0 6.0 6.0 4.9 6.0 5.0 6.0 6.0

Signal Timing for SR 535 Intersected with Meadow Creek Drive

Intersection 12 NBL SB EB/WB SBL NB


Before yellow 4.3 4.3 3.6 4.3 4.3

Current Yellow 5.5 4.9 4 4.9 5.5

propped Yellow 6 5.5 4.6 5.5 6

Before ALL-red 2.9 2.7 4.2 3.0 2.6

Current ALL-red 5.2 3.0 4.9 5.3 2.9

Signal Timing for SR 535 Intersected with Vineland Ave/I-4 EB Ramp

Intersection 13 SBL NB WBL EB

Approach Speed 45 45 35 25

Before yellow 3.9 3.9 3.6 3

Current Yellow 4.8 4.8 4.1 3.4

propped Yellow 5.4 5.4 4.7 4

Before ALL-red 3.2 3.4 4.5 4.0

Current ALL-red 5.7 3.9 6.0 6.0

Signal Timing for SR 535 Intersected with I-4 off Ramp

Intersection 14 NBL SB WBL

Approach Speed 45 40 45

Before yellow 3.9 3.9 3.6

Current Yellow 4.8 4.5 4.8

propped Yellow 5.4 5.1 5.4

Before ALL-red 4.6 5.1 4.0

Current ALL-red 6.0 5.9 6.0

89

Signal Timing for SR 535 Intersected with Hotel Plaza Blvd

Intersection 15 NBL SB EB WB SBL NB


Before yellow 3.9 3.9 3.6 3.6 3.9 3.9

Current Yellow 4.5 4.5 4.1 4 4.5 4.5

propped Yellow 5.1 5.1 4.7 4.6 5.1 5.1

Before ALL-red 3.6 3.2 4.3 4.5 3.2 3.6

Current ALL-red 5.7 3.7 5.0 6.0 5.2 4.1

Signal Timing for SR 535 Intersected with Palm Parkway/CR 535

Intersection 16 NBL SB EBL WB SBL NB WBL EB

Approach Speed 45 45 45 30 45 45 30 45

Before yellow 4.7 4.7 3.9 3.2 4.7 4.7 3.2 3.9

Current Yellow 5.1 5.1 4.3 3.6 5.1 5.1 3.6 4.3

propped Yellow 5.7 5.7 4.9 4.2 5.7 5.7 4.2 4.9

Before ALL-red 2.9 3.6 3.5 5.2 3.6 2.9 5.2 3.5

Current ALL-red 5.2 4.1 6.0 6.0 6.0 3.3 6.0 3.9

Signal Timing for SR 535 Intersected with Vinings Way Blvd

Intersection 17 SB WB SBL NB EB


Before yellow 4.7 4.7 4.7 4.7 3

Current Yellow 5.1 5.1 5.1 5.1 3.4

propped Yellow 5.7 5.7 5.7 5.7 4

Before ALL-red 2.2 4.0 2.2 2.9 3.5

Current ALL-red 2.4 6.0 3.9 3.2 6.0

Signal Timing for SR 535 Intersected with Lake Street

Intersection 18 SBL NB WB SB


Before yellow 4.7 4.7 3 4.7


propped Yellow 5.7 5.7 4 5.7



90

Signal Timing for SR 536 Intersected with World Center Dr.

Intersection 19 WBL EB NBL SB EBL WB SBL NB

Approach Speed 55 55 25 25 45 55 25 25

Before yellow 5.0 5.0 3.6 3.0 5.0 5.0 3.0 3.6

Current Yellow 5.5 5.6 4 3.4 5.6 5.5 3.4 4.0

propped Yellow 6.0 6.0 4.6 4.0 6.0 6.0 4.0 4.6

Before ALL-red 2.5 2.3 3.5 4.5 3.1 2.4 3.5 4.5

Current ALL-red 5.6 2.5 6.0 6.0 5.6 5.2 6.0 6.0

Signal Timing for SR 536 Intersected with International Dr.

Intersection 20 EBL WB EB SB


Before yellow 4.3 4.3 4.3 4.3


propped Yellow 5.3 5.3 5.3 5.3



91

APPENDIX [B]: VOLUME AND SPLITS FOR THE STUDIED

SIGNALIZED INTERSECTIONS

92

Volume and splits for SR 50 Intersected with Vizcaya Lake Road

Intersection 1 EBT EBR WBL WBT NBL NBR

AM Peak Volume(vph) 796 18 33 620 72 48

MID Volume (vph) 951 72 56 877 70 52

PM peak Volume (vph) 969 71 81 1005 97 73

AM splits (seconds) 95 25 120 30 30

MID splits (seconds) 110 20 130 20 20

PM splits (seconds) 120 30 150 30 30

Volume and splits for SR 50 Intersected with Good Home Road

Intersection 2 EBL ET EBR WBL WBT WBR NBL NBT NBR SBL SBT SBR

AM Vol. 57 637 170 153 478 23 180 214 164 110 690 87

MID Vol. 68 723 103 130 601 50 252 250 151 148 304 76

PM Vol. 115 667 172 201 712 73 370 598 230 162 373 76

AM splits (s) 20 52 52 24 56 56 22 52 52 22 52

MID splits (s) 25 70 70 25 70 70 25 30 30 25 30

PM splits (s) 25 70 70 25 70 70 35 50 50 35 50

Volume and splits for SR 50 Intersected with Apopka Vineland Road

Intersection 3 EBL ET EBR WBL WBT WBR NBL NBT NBR SBL SBT SBR

AM Vol. (vph) 79 746 38 74 533 253 44 51 141 696 111 165

MID Vol.(vph) 107 652 125 186 792 276 126 116 218 345 154 125

PM Vol. (vph) 182 676 81 242 975 670 132 212 203 404 149 167

AM splits (s) 25 70 70 25 70 70 25 25 25 50 50 50

MID splits (s) 24 57 57 30 63 63 30 53 53 30 53 53

PM splits (s) 30 57 57 38 65 65 32 53 53 32 53 53

Volume and splits for SR 50 Intersected with Dorscher Road

Intersection 4 EBL EBT EBR WBL WBT WBR NBL NBT NBR SBL SBT SBR

AM Vol. (vph) 33 1223 239 46 639 53 122 60 58 141 136 36

MID Vol.(vph) 26 940 142 59 1060 49 121 58 73 65 60 21

PM Vol. (vph) 62 943 199 88 1549 89 236 167 54 75 64 36

AM splits (s) 25 86 86 25 86 25 34 25 34

MID splits (s) 20 72 72 20 72 24 54 24 54

PM splits (s) 25 85 85 25 85 35 35 20 35

93

Volume and splits for SR 50 Intersected with Highland Lakes Center


AM Vol. (vph) 11 1348 28 7 708 16 26 3 10 9 0 10

MID Vol.(vph) 96 919 55 22 889 116 100 13 16 85 15 59

PM Vol. (vph) 90 994 73 26 1472 102 135 17 23 92 12 71

AM splits (s) 25 125 125 25 125 125 20 20 20 20

MID splits (s) 25 115 115 25 115 115 30 30 30 30

PM splits (s) 25 115 115 25 115 115 40 40 40 40

Volume and splits for SR 50 Intersected with CR 435 (Hiawassee Road)


AM Vol. (vph) 77 973 344 142 562 125 236 526 126 307 953 118

MID Vol.(vph) 161 605 189 180 964 256 307 406 117 199 516 153

PM Vol. (vph) 186 678 151 229 1300 432 359 698 143 235 626 154

AM splits (s) 20 64 64 20 64 64 28 58 58 28 58 58

MID splits (s) 24 65 65 24 65 65 28 53 53 28 53 53

PM splits (s) 25 68 68 25 68 68 34 53 53 34 53 53

Volume and splits for SR 50 Intersected with Powers Drive


AM Vol. (vph) 43 1241 132 107 660 55 84 99 51 185 203 24

MID Vol.(vph) 88 877 111 146 1010 100 147 113 70 138 144 42

PM Vol. (vph) 122 851 129 130 1498 130 196 203 34 146 163 57

AM splits (s) 25 70 70 25 70 20 55 20 55

MID splits (s) 25 65 65 30 70 20 55 20 55

PM splits (s) 26 75 75 26 75 24 55 24 55

Volume and splits for SR 50 Intersected with Paul Street


AM Vol. (vph) 29 1414 77 72 787 36 35 19 80 65 22 34

MID Vol.(vph) 57 1094 10 58 1199 43 39 7 48 34 10 24

PM Vol. (vph) 43 1195 19 61 1749 39 24 19 51 27 10 21

AM splits (s) 24 92 24 92 54 54 54 54

MID splits (s) 20 96 20 96 54 54 54 54

PM splits (s) 25 100 25 100 55 55 55 55

94

Volume and splits for SR 50 Intersected with Hastings Street


AM Vol. (vph) 73 1474 4 10 861 132 4 0 2 294 0 85

MID Vol.(vph) 61 1103 0 33 1188 140 1 0 2 122 2 48

PM Vol. (vph) 80 1167 1 32 1791 265 2 0 3 179 1 69

AM splits (s) 15 25 15 32 32 15 15 15 15

MID splits (s) 20 86 20 86 86 15 15 49 49

PM splits (s) 25 100 25 100 100 20 20 35 35

Volume and splits for SR 50 Intersected with SR 435 (Kirkman Road)


AM Vol. (vph) 39 1001 594 493 661 17 355 103 620 26 123 18

MID Vol.(vph) 65 771 231 454 997 42 382 105 359 24 67 31

PM Vol. (vph) 61 812 357 697 1375 79 716 259 398 31 89 30

AM splits (s) 20 62 32 74 74 52 52 52 24 24

MID splits (s) 20 58 35 73 73 51 51 51 26 26

PM splits (s) 20 50 48 78 78 52 52 52 30 30

Volume and splits for SR 535 Intersected with SR 536


AM Vol. (vph) 32 314 229 257 877 340 529 1296 365 206 782 180

MID Vol.(vph) 69 435 375 333 563 244 360 940 364 210 1140 198

PM Vol. (vph) 106 891 872 482 705 257 348 978 382 463 2174 129

AM splits (s) 17 43 43 31 57 57 44 63 63 23 42 42

MID splits (s) 30 37 33 30 37 37 33 69 69 24 60 60

PM splits (s) 33 50 30 38 55 55 30 69 69 33 72 72

Volume and splits for SR 535 Intersected with Meadow Creek Drive


AM Vol. (vph) 110 0 48 14 1 57 48 1603 4 48 991 70

MID Vol.(vph) 279 4 119 26 4 46 99 115 31 122 1240 140

PM Vol. (vph) 258 2 89 22 5 56 80 1530 26 108 2306 131

AM splits (s) 53 53 53 53 53 21 86 21 86 86

MID splits (s) 50 50 50 50 50 20 90 20 90 90

PM splits (s) 50 50 50 50 50 24 116 24 116 116

95

Volume and splits for SR 535 Intersected with Vineland Ave/I-4 EB Ramp


AM Vol. (vph) 239 154 96 137 0 500 1 1547 239 459 929 27

MID Vol.(vph) 259 173 143 260 0 579 0 1239 273 558 1151 26

PM Vol. (vph) 644 383 206 301 0 618 0 1464 334 780 2073 9

AM splits (s) 44 19 25 25 87 87 29 116

MID splits (s) 43 23 20 20 75 42 117

PM splits (s) 73 33 40 40 73 44 117

Volume and splits for SR 535 Intersected with I-4 off Ramp


AM Vol. (vph) 0 0 0 600 0 847 178 1198 0 0 815 758

MID Vol.(vph) 0 0 0 719 0 691 222 1058 0 0 1575 0

PM Vol. (vph) 0 0 0 1175 0 883 253 1577 0 0 2120 0

AM splits (s) 65 65 35 95 60

MID splits (s) 54 54 40 106 66

PM splits (s) 70 70 48 120 72

Volume and splits for SR 535 Intersected with Hotel Plaza Blvd


AM Vol. (vph) 111 39 351 71 45 38 800 1233 110 63 1637 318

MID Vol.(vph) 194 70 663 211 138 70 523 1011 174 139 1134 235

PM Vol. (vph) 500 73 1125 160 70 70 704 1633 185 114 1479 242

AM splits (s) 28 28 13 20 20 13 48 48 15 63 63

MID splits (s) 27 27 13 22 22 13 39 39 23 62 62

PM splits (s) 35 35 13 24 24 13 58 58 24 82 82

Volume and splits for SR 535 Intersected with Palm Parkway/CR 535


AM Vol. (vph) 281 327 879 297 173 27 591 588 280 15 1030 460

MID Vol.(vph) 258 240 529 270 210 59 571 584 269 45 610 199

PM Vol. (vph) 491 302 820 346 401 51 658 1111 451 48 747 248

AM splits (s) 24 43 25 44 34 77 77 15 58 58

MID splits (s) 27 43 28 44 36 73 73 16 53 53

PM splits (s) 35 50 29 44 36 87 87 24 75 75

96

Volume and splits for SR 535 Intersected with Vinings Way Blvd


AM Vol. (vph) 6 6 26 112 12 11 30 535 82 12 1366 22

MID Vol.(vph) 11 5 32 98 8 40 32 621 90 17 598 26

PM Vol. (vph) 25 10 37 122 13 29 44 1266 129 26 704 25

AM splits (s) 45 45 45 45 100 100 15 115

MID splits (s) 58 58 58 58 82 82 20 102

PM splits (s) 24 24 45 45 115 115 30 145

Volume and splits for SR 535 Intersected with Lake Street


AM Vol. (vph) 0 0 0 48 0 15 0 419 52 94 1352 0

MID Vol.(vph) 0 0 0 55 0 46 0 633 29 50 571 0

PM Vol. (vph) 0 0 0 87 0 81 0 1243 48 56 633 0

AM splits (s) 30 36 14 50

MID splits (s) 32 33 15 48

PM splits (s) 45 35 15 50

Volume and splits for SR 536 Intersected with World Center Dr.


AM Vol. (vph) 82 437 10 19 1423 254 57 55 123 62 11 116

MID Vol.(vph) 123 798 33 19 988 212 18 29 33 132 14 164

PM Vol. (vph) 87 1510 42 59 1149 174 32 16 76 192 22 249

AM splits (s) 20 95 25 20 95 24 20 24 21 25 25

MID splits (s) 20 100 20 20 100 20 20 20 20 20 20

PM splits (s) 17 42 20 18 43 16 15 16 19 20 20

Volume and splits for SR 536 Intersected with International Dr.


AM Vol. (vph) 415 286 0 21 996 190 0 0 0 52 4 401

MID Vol.(vph) 434 447 1 13 387 94 0 0 0 92 8 570

PM Vol. (vph) 534 1050 3 5 418 111 0 0 0 261 12 823

AM splits (s) 25 60 35 35 35 20 20 20

MID splits (s) 36 60 24 24 24 20 20 20

PM splits (s) 35 70 35 35 35 25 25 25

97

APPENDIX [C]: THE GENERAL CHARACTERISTICS OF THE STUDIED

SIGNALIZED INTERSECTIONS

\

98

SR 50 Signalized Intersections Characteristics (AM pattern1)

Intersection No. No. of Approaches No. of Splits Cycle length (s)











SR 535&536 Signalized Intersections Characteristics (AM Pattern 1)












SR 50 Arterial Signalized Intersections Characteristics (AM Pattern 2)












99

SR 535&536 Arterial Signalized Intersections Characteristics (AM Pattern 2)












SR 50 Arterials Signalized Intersections Efficiency Measurements (AM Pattern 3)












SR 535&536 Arterial Signalized Intersections Characteristics (AM Pattern 3)












100

SR 50 Arterial Intersections Characteristics (Midday Pattern 1)

intersection No. No. of Approaches No. of Splits Cycle length (s)











SR 535 & SR 536 Arterials Intersections Characteristics (Midday Pattern 1)
























101





































102

SR 50 Arterial Intersections Characteristics (PM Pattern 1)












SR 535 & SR 536 Arterials Intersections Characteristics (PM Pattern 1)
























103





































104

APPENDIX [D]: THE SIGNAL TIMING EFFICIENCY MEASUREMENTS

OF THE STUDIED SIGNALIZED INTERSECTIONS

105

SR 50 Signalized Intersections Efficiency Measurements (AM pattern 1)

intersection No. Total Del/Veh. (s) 95th queue length (ft) V/C ICU

Intersection 1 14.9 129 0.40 51.50

Intersection 2 42.6 254 0.62 69.30

Intersection 3 42.3 142 0.57 63.20

Intersection 4 38.2 113 0.57 68.3

Intersection 5 11.1 29 0.42 49.9

Intersection 6 50.9 76 0.78 81.5

Intersection 7 46.6 172 0.61 72.8

Intersection 8 24.3 144 0.52 62.5

Intersection 9 21.7 42 0.56 61.9

Intersection 10 47.1 455 0.83 85.8

Average 33.97 155.6 0.59 66.67

SR 535&536 Signalized Intersections Efficiency Measurements (AM pattern 1)


Intersection 11 173.1 738 0.83 76.8

Intersection 12 21.4 127 0.49 60.7

Intersection 13 72 311 0.77 79.4

Intersection 14 54.4 339 0.69 73.3

Intersection 15 34.9 427 0.74 77.7

Intersection 16 127.4 425 0.87 89.5

Intersection 17 39.8 194 0.55 60.7

Intersection 18 61.2 230 0.53 49.5

Intersection 19 24.3 86 0.53 63.7

Intersection 20 15.9 130 0.52 61.9

Average 62.44 300.7 0.83 69.32

SR 50 Arterial Signalized Intersections Efficiency Measurements (AM pattern 2)

Intersection No. Total Del/Veh. (s) 95th queue length (ft) V/C ICU

Intersection 1 16.5 130 0.43 43.9

Intersection 2 44.7 291 0.65 75.4

Intersection 3 49 163 0.59 66.6

Intersection 4 41.2 101 0.58 71.9

Intersection 5 16.2 35 0.43 51.5

Intersection 6 53.3 82 0.81 87.6

Intersection 7 56.6 228 0.64 76.9

Intersection 8 33.4 148 0.53 66.2

Intersection 9 37.7 49 0.58 65.2

Intersection 10 72 633 0.85 87.8

Average 42.06 186 0.61 69.30

106

SR 535&536 Arterials Signalized Intersections Efficiency Measurements (AM pattern 2)


Intersection 11 175.6 741 0.9 86.1

Intersection 12 20.2 148 0.51 62.3

Intersection 13 97.9 438 0.82 83.9

Intersection 14 64.3 365 0.72 76.4

Intersection 15 45.7 428 0.77 81.8

Intersection 16 118.5 344 0.91 92.6

Intersection 17 60.1 213 0.57 63.2

Intersection 18 56 144 0.57 52

Intersection 19 44.6 189 0.57 72.9

Intersection 20 18.8 171 0.55 63.5

Average 70.17 318.1 0.69 73.47

SR 50 Arterial Signalized Intersections Efficiency Measurements (AM pattern 3)


Intersection 1 18.5 135.5 0.44 45.2

Intersection 2 45.9 271 0.66 77.4

Intersection 3 48.6 140 0.6 68.4

Intersection 4 46.9 93 0.59 74.4

Intersection 5 14.9 42 0.43 52.5

Intersection 6 59.7 93 0.83 89.6

Intersection 7 54 212 0.65 79.2

Intersection 8 45.8 152 0.54 67.7

Intersection 9 38.9 35 0.59 66.7

Intersection 10 67.1 457 0.86 89.2

Average 44.03 163.05 0.62 71.03

SR 535&536 Arterials Signalized Intersections Efficiency Measurements (AM pattern 3)


Intersection 11 174.6 737 0.91 87.6

Intersection 12 60.8 200 0.51 63.3

Intersection 13 113.1 520 0.83 85.4

Intersection 14 59.4 354 0.73 77.4

Intersection 15 46.7 378 0.78 83.3

Intersection 16 112.7 352 0.93 94.6

Intersection 17 45.8 198 0.58 64.2

Intersection 18 63.7 180 0.58 53

Intersection 19 34.1 91 0.58 74.7

Intersection 20 21 174 0.56 63.8

Average 73.19 318.4 0.70 74.73

107

SR 50 Arterial Intersections Efficiency Measurements (Midday pattern 1)


Intersection 1 13.9 129 0.51 54.1

Intersection 2 38.3 220 0.51 61.7

Intersection 3 43.9 271 0.58 64.3

Intersection 4 33.5 79 0.5 62.2

Intersection 5 17.4 146 0.38 52.2

Intersection 6 44.2 262 0.64 71.4

Intersection 7 74.9 262 0.64 70.5

Intersection 8 24.3 115 0.41 51

Intersection 9 15 141 0.42 53.9

Intersection 10 41.3 247 0.62 63

Average 34.67 187.2 0.521 60.43

SR 535 & SR 536 Arterials Intersections Efficiency Measurements (Midday pattern 1)


Intersection 11 123.6 894 0.67 72.3

Intersection 12 37.7 339 0.59 66.2

Intersection 13 46 315 0.66 70.6

Intersection 14 34.8 468 0.76 76.8

Intersection 15 45.5 285 0.65 68.8

Intersection 16 46.3 349 0.66 72

Intersection 17 11.1 155 0.34 48.6

Intersection 18 6.5 57 0.34 39.7

Intersection 19 25.3 222 0.45 52.3

Intersection 20 14.9 120 0.47 40

Average 39.17 320.4 0.559 60.73



Intersection 1 15.5 151 0.52 56.5

Intersection 2 40.9 231 0.53 67

Intersection 3 53.5 291 0.62 69.1

Intersection 4 52.6 113 0.53 65.9

Intersection 5 21.4 152 0.39 55.5

Intersection 6 45 266 0.66 77.2

Intersection 7 59.8 244 0.67 75.1

Intersection 8 21.6 130 0.42 54.6

Intersection 9 16.9 146 0.44 57.1

Intersection 10 43 309 0.63 65.5

Average 37.02 203.3 0.541 64.35

108



Intersection 11 118.5 878 0.72 79.3

Intersection 12 34.5 351 0.61 70.5

Intersection 13 59.1 325 0.69 76.1

Intersection 14 38.7 501 0.79 79.9

Intersection 15 47.7 298 0.68 74.6

Intersection 16 50.1 361 0.69 75.1

Intersection 17 17.5 194 0.35 51.2

Intersection 18 10.2 111 0.36 44

Intersection 19 28.4 288 0.49 59.2

Intersection 20 15.2 180 0.48 41.7

Average 41.99 348.7 0.586 65.16



Intersection 1 17.5 132 0.53 58

Intersection 2 43.2 246 0.54 69

Intersection 3 49.2 277 0.63 71.4

Intersection 4 41.4 140 0.53 68.4

Intersection 5 20.8 132 0.39 57

Intersection 6 47.6 265 0.67 79.2

Intersection 7 95.5 263 0.68 77.4

Intersection 8 27.3 123 0.42 56.1

Intersection 9 15.4 145 0.45 58.6

Intersection 10 41.7 294 0.64 67.2

Average 39.96 201.7 0.548 66.23



Intersection 11 132.4 860 0.73 80.8

Intersection 12 34.1 357 0.62 71.9

Intersection 13 62 351 0.7 77.6

Intersection 14 37.9 399 0.8 80.9

Intersection 15 55.4 273 0.69 76.6

Intersection 16 57.3 448 0.7 77.1

Intersection 17 16.1 175 0.35 52.2

Intersection 18 10.5 110 0.37 45.5

Intersection 19 22.7 186 0.49 60.4

Intersection 20 15.1 184 0.49 42.9

Average 44.35 334.3 0.594 66.59

109

SR 50 Arterial Intersections Efficiency Measurements (PM Pattern 1)


Intersection 1 12.3 129 0.34 46.8

Intersection 2 47.2 413 0.68 74.9

Intersection 3 58.6 322 0.83 83.5

Intersection 4 67.1 165 0.8 81.1

Intersection 5 23.8 164 0.55 65.1

Intersection 6 58.8 349 0.82 82.8

Intersection 7 45.2 256 0.77 87

Intersection 8 33.9 233 0.53 61

Intersection 9 21.2 178 0.62 68.5

Intersection 10 54 338 0.86 87.2

Average 42.21 254.7 0.34 73.79

SR 535 & SR 536 Arterials Intersections Efficiency Measurements (PM Pattern 1)


Intersection 11 322.4 909 1.11 109.3

Intersection 12 37.7 451 0.73 78.3

Intersection 13 62.8 255 1.06 88.9

Intersection 14 111.8 576 1.25 120.3

Intersection 15 166 901 0.87 87

Intersection 16 160.1 759 0.85 86.3

Intersection 17 42.5 207 0.59 62.4

Intersection 18 39 284 0.59 61.1

Intersection 19 110.2 239 0.65 62.4

Intersection 20 19 144 0.62 60

Average 107.15 472.5 0.832 81.6



Intersection 1 12.8 151 0.34 48.5

Intersection 2 50.4 401 0.71 81

Intersection 3 77.1 326 0.86 86.9

Intersection 4 73.5 175 0.82 85

Intersection 5 28 182 0.57 68.3

Intersection 6 57.3 337 0.85 89

Intersection 7 50.6 323 0.79 91.7

Intersection 8 37.1 284 0.55 64.6

Intersection 9 20.8 144 0.64 71.7

Intersection 10 53 432 0.88 90.8

Average 46.06 275.5 0.701 77.75

110



Intersection 11 347.1 906 1.18 117.3

Intersection 12 69.3 593 0.75 82.9

Intersection 13 105.6 271 1.11 94.7

Intersection 14 119.2 636 1.3 123.4

Intersection 15 169.7 983 0.9 92.7

Intersection 16 169.1 950 0.89 92.1

Intersection 17 21.3 178 0.61 65

Intersection 18 15.8 182 0.63 65.4

Intersection 19 113 232 0.73 67.5

Intersection 20 20.8 155 0.64 61.6

Average 115.09 508.6 0.874 86.26



Intersection 1 14.9 132 0.35 50.3

Intersection 2 63.1 542 0.71 83

Intersection 3 80.2 417 0.87 88.6

Intersection 4 77.5 277 0.83 87.5

Intersection 5 26.6 193 0.57 69.9

Intersection 6 54.9 388 0.86 91

Intersection 7 68.3 431 0.8 93.9

Intersection 8 26.8 172 0.55 66.1

Intersection 9 30.5 190 0.65 73.2

Intersection 10 57.9 521 0.89 92.2

Average 50.07 326.3 0.708 79.57



Intersection 11 307.9 903 1.19 118.8

Intersection 12 88.6 606 0.76 84.3

Intersection 13 114.2 270 1.12 96.2

Intersection 14 111.4 627 1.31 124.4

Intersection 15 175.6 958 0.91 94.7

Intersection 16 190.5 904 0.91 94.1

Intersection 17 18.5 197 0.61 66

Intersection 18 13 89 0.65 66.9

Intersection 19 116.7 239 0.75 68.7

Intersection 20 20.6 161 0.65 62.9

Average 115.7 495.4 0.886 87.7

111

APPENDIX [E]: DILEMMA AND OPTION ZONES IDENTIFICATION OF

THE STUDIED SIGNALIZED INTERSECTIONS

112

intersection 1 WB NB WBL EB NBL

XC (ft) 284.9 284.9 104.3 284.9 104.3

X0 Pattern 1 (ft) 253.9 113.5 118.6 253.9 22.3

XC-X0 Pattern 1 31.0 171.5 -14.3 31.0 82.0

X0 pattern 2 (ft) 305.8 148.7 155.8 284.7 45.8

XC-X0 Pattern2 -20.8 136.2 -51.5 0.2 58.5

X0 pattern 3 (ft) 360.1 204.6 195.4 360.1 84.0

XC-X0 Pattern 3 -75.1 80.3 -91.1 -75.1 20.3


XC (ft) 284.9 284.9 284.9 284.9 284.9 284.9 284.9 284.9

X0 Pattern 1 (ft) 243.9 243.9 209.9 209.9 227.9 227.9 207.9 207.9

XC-X0 Pattern 1 41.0 41.0 75.0 75.0 57.0 57.0 77.0 77.0

X0 pattern 2 (ft) 274.7 274.7 261.8 261.8 258.7 258.7 259.8 259.8

XC-X0 Pattern2 10.2 10.2 23.2 23.2 26.2 26.2 25.2 25.2

X0 pattern 3 (ft) 350.1 350.1 316.1 316.1 334.1 334.1 314.1 314.1

XC-X0 Pattern 3 -65.1 -65.1 -31.1 -31.1 -49.1 -49.1 -29.1 -29.1


XC (ft) 284.9 284.9 284.9 104.3 284.9 284.9 104.3 284.9

X0 Pattern 1 (ft) 198.9 198.9 215.9 -12.8 257.9 257.9 -10.8 217.9

XC-X0 Pattern 1 86.0 86.0 69.0 117.0 27.0 27.0 115.0 67.0

X0 pattern 2 (ft) 229.7 229.7 246.7 10.8 288.7 288.7 12.8 248.7

XC-X0 Pattern2 55.2 55.2 38.2 93.5 -3.8 -3.8 91.5 36.2

X0 pattern 3 (ft) 305.1 305.1 322.1 49.0 364.1 364.1 51.0 324.1

XC-X0 Pattern 3 -20.1 -20.1 -37.1 55.3 -79.1 -79.1 53.3 -39.1


XC (ft) 284.9 284.9 141.3 141.3 284.9 284.9 141.3 141.3

X0 Pattern 1 (ft) 269.9 269.9 43.6 43.6 283.9 283.9 29.6 29.6

XC-X0 Pattern 1 15.0 15.0 97.7 97.7 1.0 1.0 111.7 111.7

X0 pattern 2 (ft) 300.7 300.7 57.6 57.6 314.7 314.7 43.6 43.6

XC-X0 Pattern2 -15.8 -15.8 83.7 83.7 -29.8 -29.8 97.7 97.7

X0 pattern 3 (ft) 376.1 376.1 117.7 117.7 390.1 390.1 103.7 103.7

XC-X0 Pattern 3 -91.1 -91.1 23.6 23.6 -105.1 -105.1 37.6 37.6

113

intersection 5 EBL WB NB WBL EB SB

XC (ft) 284.9 284.9 104.3 284.9 284.9 104.3

X0 Pattern 1 (ft) 269.9 269.9 -18.8 265.9 265.9 -19.8

XC-X0 Pattern 1 15.0 15.0 123.0 19.0 19.0 124.0

X0 pattern 2 (ft) 300.7 300.7 10.9 296.7 296.7 9.9

XC-X0 Pattern2 -15.8 -15.8 93.4 -11.8 -11.8 94.4

X0 pattern 3 (ft) 376.1 376.1 43.0 372.1 372.1 42.0

XC-X0 Pattern 3 -91.1 -91.1 61.3 -87.1 -87.1 62.3

114

REFERENCES

Aashto, A. (2001). Policy on geometric design of highways and streets. American Association of

State Highway and Transportation Officials, Washington, DC, 3, 3.2.

Bonneson, J., & Zimmerman, K. (2004). Effect of yellow-interval timing on the frequency of

red-light violations at urban intersections. Transportation Research Record: Journal of

the Transportation Research Board(1865), 20-27.

Caird, J. K., Chisholm, S., Edwards, C. J., & Creaser, J. I. (2007). The effect of yellow light

onset time on older and younger drivers’ perception response time (PRT) and intersection

behavior. Transportation research part F: traffic psychology and behaviour, 10(5), 383-

396.

Chang, M.-S., Messer, C. J., & Santiago, A. J. (1985). Timing traffic signal change intervals

based on driver behavior.

Click, S. M. (2008). Application of the ITE Change and Clearance Interval Formulas in North

Carolina. Institute of Transportation Engineers. ITE Journal, 78(1), 20.

Click, S. M., & Jones, D. L. (2006). Calculation of Yellow Change and All-Red Clearance

Intervals: North Carolina Experience. Paper presented at the Transportation Research

Board 85th Annual Meeting.

Code, U. V., & Ordinance, M. T. (2000). National Committee on Uniform Traffic Laws and

Ordinances.Uniform Vehicle Code. US Government Printing Office.

Crommelin, R. (1974). Employing Intersection Capacity Utilization Values to Estimate Overall

Level of Service. Traffic Engineering, 44(10).

El-Shawarby, I., Rakha, H., Inman, V., & Davis, G. (2006). Effect of yellow-phase trigger on

driver behavior at high-speed signalized intersections. Paper presented at the Intelligent

Transportation Systems Conference, 2006. ITSC'06. IEEE.

FDOT. (2002a). Traffic Engineering Manual, Revised 2010.

FDOT. (2002b). Traffic Engineering Manual,Revised 2013.

Gazis, D., Herman, R., & Maradudin, A. (1960). The problem of the amber signal light in traffic

flow. Operations Research, 8(1), 112-132.

ITE, D. V. C. (1985). A Proposed Recommended Practice. Institute of Transportation Engineers

Journal, 55(5), 61-64.

115

Kennedy, N., Kell, J. H., & Homburger, W. S. (1963). Fundamentals of Traffic Engineering.

ITTE. Univ. of California, Berkeley.

Knodler Jr, M., & Hurwitz, D. (2009). An evaluation of dilemma zone protection practices for

signalized intersection control. Rep. No, 6.

Köll, H., Bader, M., & Axhausen, K. W. (2004). Driver behaviour during flashing green before

amber: a comparative study. Accident Analysis & Prevention, 36(2), 273-280.

McGee, H., Moriarty, K., Eccles, K., Liu, M., Gates, T., & Retting, R. (2012). Guidelines for

Timing Yellow and All-Red Intervals at Signalized Intersections (No. 731). Washington,

DC: Transportation Research Board.

MUTCD. (2003). Manual on Uniform Traffic Control Devices.

Olson, P. L., & Rothery, R. W. (1961). Driver response to the amber phase of traffic signals.

Operations Research, 9(5), 650-663.

OrangeCounty. (2011a). SR 50 Signal Retiming Report. Retrieved from

OrangeCounty. (2011b). SR 535 and SR 536 Final Signal Retiming. Retrieved from

OrangeCounty. (2014). SR 535 and SR 536 Change and Clearance Interval Update. Retrieved

from

OrangeCounty. (2015). SR 50 Signal Retiming Update. Retrieved from

Parsonson, P. S. (1992). Signal timing improvement practices.

Pline, J. L. (1975). Traffic control devices handbook, an Operation Guide: Inst of Transportation

Engrs.

Pline, J. L. (1999). Traffic engineering handbook: Prentice Hall.

Rakha, H., El-Shawarby, I., & Setti, J. R. (2007). Characterizing driver behavior on signalized

intersection approaches at the onset of a yellow-phase trigger. Intelligent Transportation

Systems, IEEE Transactions on, 8(4), 630-640.

Retting, R. A., Ferguson, S. A., & Farmer, C. M. (2008). Reducing red light running through

longer yellow signal timing and red light camera enforcement: results of a field

investigation. Accident Analysis & Prevention, 40(1), 327-333.

116

Saito, T., Ooyama, N., & Sigeta, K. (1990). Dilemma and option zones, the problem and

countermeasures-characteristics of zones, and a new strategy of signal control for

minimizing zones. Paper presented at the Road Traffic Control, 1990., Third International

Conference on.

Si, J., Urbanik, T., & Han, L. (2007). Effectiveness of Alternative Detector Configurations for

Option Zone Protection on High-Speed Approaches to Traffic Signals. Transportation

Research Record: Journal of the Transportation Research Board(2035), 107-113.

Taoka, G. T. (1989). Brake reaction times of unalerted drivers. ITE journal, 59(3), 19-21.

Thompson, B. A. (1994). Determining Vehicle Signal Change And Clearance Intervals: Institute

of Transportation Engineers.

Wei, H. (2008). Characterize dynamic dilemma zone and minimize its effect at signalized

intersections.

Zegeer, C. V. (1977). Effectiveness of green-extension systems at high-speed intersections.

Impact of the longer change and clearance intervals on ...

Documents

Transcript of Impact of the longer change and clearance intervals on ...