IMPACT OF TRANSIT SIGNAL PRIORITY (TSP) ON BUS TRAVEL

TIMES, LATE BUS RECOVERY, DELAY AND LEVEL OF SERVICE (LOS)

Presenter: Sotonye Ikiriko1, Deo Chimba1

College of Engineering, Tennessee State University, Nashville TN 37209 USA

21st June 2018

Introduction ! Transit Signal Priority (TSP)

" A strategy to Speed up Transit Vehicle Movement

! Benefits " Boost Transit Movement Without

undue Impact on other Road Users " Reduce Bus Bunching " Improve Transit (bus) Schedule

Adherence " Reduce High Auto Dependency " Expand Mobility Choices " Improve Transit ridership " Reduce Energy consumption, green

house Gases and other Pollutants

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Principle of TSP Operation ! Components

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"  Transit vehicle

detection system

" Communication system

"  Traffic signal control system

Why TSP? ! Nashville is fast growing

" According to Randall Gross everyday 85 people come into Nashville

!  High traffic congestion

! Poor bus serviceability

! Poor Schedule Adherence

! Transit unattractiveness " According to David Hartgen only

1.5 to 2.5% of Nashville Residents use Transit

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Study Corridor

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! Gallatin Pike corridor ! 12.3 miles Long ! An arterial roadway !  two lanes in each direction ! continuous left turn lane ! 48 signalised intersections ! 104 posted bus stops

Modelled Section of Gallatin Corridor ! 1.83 Miles Long ! Two lanes in each Direction ! Continuous left turn lane ! 9 signalized Intersection ! 7 bus stops in each direction

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Research Objectives Evaluate the impact of TSP on; ! Transit operation " Bus Schedule Adherence in Terms of Late bus

recovery at bus Stop level " Bus Travel Time Reduction " Mainline and Side Street Delays

! Intersection Level of Service (LOS)

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Methodology ! Microsimulation Software Selection

" VISSIM ! Data collection

! Origin Destination (OD) Matrix Estimation and Validation " Principle of Conservation Of Vehicles

! Base Model Development in VISSIM ! Base Model Calibration and Validation

" Alternative Concept " TSP " VAP code: Green extension and Red truncation TSP strategies

Data Collection ! Roadway Geometry

" Intersection Layout " Lane Configuration " Bus Stop location and Types

! Traffic Data " Turning Movement Count(TMC) " General Traffic Travel Time

! Transit Data " Speed Profile " Bus travel Time " Boarding and Alighting Count " Ridership " Schedule Adherence

! Traffic Control Data " Signal Timing and Phasing Plans

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Base Model Development !  Corridor Geometry

!  Connectors !  Urban Motorised Driving

Behaviour "  Wiedemann 74 car

following Model !  Vehicle Composition !  Desired Speed Distribution !  Public Transportation Stops !  Public Transportation Line

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Dynamic Assignment In VISSIM

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Base Model Calibration and Validation ! OD Matrices Calibration

! Speed Calibration " Simulated and Observed

Speed (PE < 5%)

! Travel Time Validation " Simulated and Observed

Travel Time (PE < 15%)

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PE=Percentage Error

TSP Signal Logic Implementation

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! Passive Priority " It allocates more green time

to approaches having higher bus flow than it would for others ! Active Priority

" Green Extension " Red Truncation

! Vehicle Actuated Programing (VAP) Code "  Signal Timing and Phasing Plans

TSP Signal Logic Implementation in VAP Code

Bus Detector 75m from signal

Signal Head

Bus Detector 75m from signal

Minimum Recall Detectors

Gap out Detectors

Bus Stop

OD Matrix Calibration and Validation Results

y = 1.3672x - 1.9452 R² = 0.8569

0

200

400

600

800

1000

1200

1400

0 200 400 600 800 1000 1200 1400

Est

imat

ed (V

eh\h

r)

Observed (Veh\hr)

OD Matrix Validation

y = 0.9661x - 2.1964 R² = 0.9984

0

200

400

600

800

1000

1200

1400

1600

0 200 400 600 800 1000 1200 1400 1600

Sim

ulat

ed (V

eh\h

r)

Estimated (Veh\hr)

OD Matrix Calibration

Impact of TSP on Main Line Travel Time

EB= Eastbound, WB= Westbound

100

150

200

250

300

350

400

450

500

550

600

EB WB EB WB EB WB EB WB

Bus Car HGV All Vehicles

Aver

age

Trav

el T

ime

(Sec

)

MainLine Vehicle Types

Main Line Travel Time Measurement

Base Base + TSP

Impact of TSP on Main Line Vehicle Delay

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0

50

100

150

200

250

300

EB WB EB WB EB WB EB WB

Bus Car HGV All Vehicles

Vehi

cle

Del

ay (s

ec)

Main Line Approach

Main Line Vehicle Delay Base Base + TSP

Late Bus Recovery at Bus Stop Level

0

50

100

150

200

250

300

350

400

Stop 1 Stop 2 Stop 3 Stop 4 Stop 5 Stop 6 Stop 7 Stop 1 Stop 2 Stop 3 Stop 4 Stop 5 Stop 6 Stop 7

PT Line 1 PT line 2

Lat

enes

s (Se

c)

PT lines and Bus Stops

Late Bus Recovery

Base Base + TSP

PT Line = Public Transportation Line

Impact of TSP on Side Street Vehicle Delay

0

20

40

60

80

100

120

NB SB NB SB NB SB NB SB NB SB NB SB NB SB NB SB NB SB

Alta Loma Unnamed River Gate Pkwy

Cude Ln Shepherd Hills

Conference Dr

Liberty Ln North Side 2284-2282 TN-6

Vehi

cle

Del

ay (S

ecs)

Intersection Approach

Side Street Delay Comparison

Base Base + TSP

SB=Southbound, NB=Northbound

Significance of TSP on Side Street Delay Group Statistics

Scenario N Mean Std. Deviation

Std. Error Mean

Delay Base 64 48.9344 21.25447 2.65681

Base + TSP

64 55.2509 20.20847 2.52606

Independent Samples Test Levene's Test for

Equality of Variances t-test for Equality of Means

F Sig. t df Sig. (2-tailed)

Mean Difference Std. Error

Difference

95% Confidence Interval of the

Difference

Lower Upper

Delay

Equal variances assumed 0.215 0.643 -1.723 126 0.087 -6.31656 3.66601 -13.57148 1

Equal variances not assumed -1.723 125.68 0.087 -6.31656 3.66601 -13.57166 1

Overall Corridor Performance In Terms of Level of Service

Intersection

Name

Intersection Delay & LOS

Base LOS Base + TSP LOS % Increase % Reduce

Alta Loma 27.3 C 31.1 C 14.0

Unnamed 21.5 C 21.5 C 0.2

Rivergate 34.1 C 42.4 D 24.3

Cude Lane 21.3 C 23.3 C 9.2

Shepherd Hills 20.9 C 21.4 C 2.2

Conference Dr 24.8 C 26.1 C 5.1

Liberty 17.1 B 17.9 B 4.6

North Side 17.7 B 18.5 B 4.4

2284-2282 TN-6 8.0 A 8.0 A 0.1

All Intersection 21.4 C 23.3 C 8.0 0.1

Conclusion • TSP will reduce bus travel time by about 5% to 10% • Reduce Travel time for other vehicles utilizing the priority

approach by about 5.8%

• Reduce bus delay by about 11% to 23% • Reduce delay for other vehicles utilizing the priority

approach by about 11.6%

• Reduce bus lateness by about 34.16% •  Increase Side Street Delay by about 15.9%

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Thank You For Listening Any Questions?