Exercise 3 - Platoon Dispersion Analysis Aditya Nugroho e

EXERCISE 3

PLATOON DISPERSION ANALYSIS

CE 5203 TRAFFIC FLOW AND CONTROL

ADITYA NUGROHO

HT083276E

DEPARTMENT OF CIVIL ENGINEERINGNATIONAL UNIVERSITY OF SINGAPORE

2010

2

Department of Civil Engineering

CE 5203 Traffic Flow and Control

1.0 INTRODUCTION

Platooning represents the clustering of traffic in urban arterial road networks. The dispersionof vehicle platoons occurs due to the differences in the desired speeds of the various driversthat make up the platoon. In this Exercise 3 the objectives are:

To understand how to traffic flows propagate macroscopically Apply PLATOON DISPERSION analysis Predict the arrival distribution pattern downstream flows at Commonwealth Ave West

intersections

Prediction of platoon dispersion is important for determining the traffic arrivals atdownstream intersections to assess the need for signal coordination and to optimize the signaltiming plans in coordinated signal systems.

2.0 PLATOON DISPERSION METHOD

A vehicle platoon is defined as a group of vehicles travelling together in the HighwayCapacity Manual (HCM 2000). Major parameters of the vehicle platoon characteristicsinclude platoon headway, and platoon speed should be selected as fundamental variables. It isimportant to select a proper value of the headway.

The value of headway can be determined based on the headway data analysis in Exercise 2.Meanwhile, for vehicle speed data collection, it is appropriate to measure by spot speedmeasurement from videotape data and multitimer software.

2.1 Data collection

In observing the platoon dispersion downstream at Commonwealth Ave West, it is essential toaddress the problems that signify the importance of the study. This study was done byidentifying the field data requirement such as position where vehicle traffic flows are recordedand ensure a short time interval for measurement. Figure 1 shows the site arrangement forvideo recording purposes and road geometry of study site (note that the estimation length ofroad geometry was obtained from Google EarthPro 5.2).

Figure 1 Study site

Jl. Lempeng(minor road)

Stop line

12

Referencepoint

3

200 m

17 m

Spot speed 12 m

3



Vehicle platoon have been measured using video camera and and data has been extractedusing appropriate computing software called MultiTimer. In this Exercise 2, several pointsshould be considered before do the measuring of time headway.

A reference line- a certain line should be set as a reference to count vehicles. Flow record- Flows were recorded per 5 second, when the vehicles pass a reference

point on a lane measured from front bumper to front bumper. Two reference pointwere selected fot this study. A referencepoint nearby tunnel nosing and Jalan lempengjunction (merging area).

Headway record – As headway data for lane 1 and 2 has been collected in exercise 2,additional headway data record is needed for Jln Lempeng.

Speed record - two reference line in the same direction has been set to determine spotspeed in Clementi Ave 6 (see Figure 1)

Vehicles type- Although it is important to measure the platoon dispersion by vehiclescomposition where heavy vehicles may affect the platoon size at downstream section.However, to simplify our exercise, we do not consider vehicle type.

2.2 Speed and platoon measurement

Along the Clementi Avenue 6 there is uncontrolled junction where Jalan Lempeng is minorroad. The vehicle exit from Jalan Lempeng has no right of way at cross roads, but is the dutyof a driver when approaching a major road to go dead slow and to give way to traffic on themajor road. Therefore it can be assume that, the speed of vehicle at major road would be notdisturbed by minor road section.

In order to measure the speed, we play the recorded video and set of reference line (see Figure1), therefore the time of every single vehicle passing through a particular length can bemeasured. Therefore spot speed can be measure by following equations:

3.6( ) ( )2 1

Du(i)=

t i t i

(1)

where, ( ) is spot speed (km/h) of vehicle i, D is the measuring distance (m), D=12m, 1( )is the front bumper entering time (s) and t2(i) is the front bumper exit time (s).

Vehicle platoon dispersion can be measured by employed the Pacey’s diffusion theory whichassume that the vehicles could travel independently, therefore the probability that trip traveltime between and + equals to the probability of speed between and + . Thus, thetravel time distribution can be expressed as ( ) ,

2(1/ 1/ )/(2 )

22

1 se

sg( )=

(2)

where, s denotes = / , and denotes travel time and average travel time respectively.Suppose that ( ) and ( ) are the flow profiles of upstream and downstream respectively,with discrete intervals of =1 interval, the flow profile at time interval j will be

4



( ) ( )ud q i g j iq (t )= (3)

3.0 Speed analysis

In order to make simplified the analysis of speed, I will not included the speed when thetraffic is congested. The speed would be only calculated in normal traffic condition. Inaddition, it is also assume that the vehicle from Clementi Avenue 6 would not make a left turnto minor road. Therefore it is assume the speed distribution would not disturbed by minorroad (Jl. Lempeng).

Table 1 Descriptive statistic of vehicles speed

Properties Lane 1 Lane 2No of vehicles (N) 96 104Mean 30.55205 28.84571Median 30.95396 28.53369Mode 29.1498 29.77257Standard Deviation 6.351596 4.753509Minimum 17.63265 20.81928Maximum 42.60355 43.9471

The normal probability plot and goodness of fit test has been done (see Appendix).

4.0 Downstream flow profile

Downstream flow profile was done by consider the inbound traffic flow from the Jln.Lempeng, assuming that mean and standard deviation of vehicle speed from Jln Lempengwould be follow the outermost lane of Clementi Avenue 6, and there is no reduction speed tosimplified the calculation, please see the Appendix in detail of calculation. In addition it isalso assume that the inbound traffic from Jln Lempeng also would use outermost lane untilreach the downstream point.

Calculation was done for all lanes to derive the journey time distribution from the referencepoint to a location 200m downstream. Therefore, we can analyze Lane 1 and Lane 2downstream pattern flow profile. As journey time is continuous variable, we need to groupjourney time into discrete intervals. In this exercise, 1 min interval is employed for simplifiedcalculation. Following table and figure represent the journey time of vehicles on each lane.

5



Lane 1Mean 30.5521 Average journey time 3.927723Std dev 6.3516 S = Std.dev/D 0.052930D 2

t g(t)1 0.0002 0.0003 0.2774 0.4695 0.1776 0.0537 0.0178 0.0069 0.00210 0.00111 0.00112 0.00013 0.00014 0.00015 0.000

Figure 2 Vehicle journey time of lane 1

Lane 2Mean 28.846 Average journey time 4.160Std dev 4.754 S = Std.dev/D 0.040D 2

t g(t)1 0.0002 0.0003 0.0714 0.6115 0.2406 0.0507 0.0108 0.0029 0.00110 0.00011 0.00012 0.00013 0.00014 0.00015 0.000

Figure 3 Vehicle journey time of lane 2

From the above journey time data, downstream flows can be measured by the Pacey’sdiffusion theory. To simplified the calculation procedure, I only consider 15 minutes upstream

0,00

0,05

0,10

0,15

0,20

0,25

0,30

0,35

0,40

0,45

0,50

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

0,00

0,10

0,20

0,30

0,40

0,50

0,60

0,70

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

6



flow. Thus, vehicles platoon for 200m downstream point for the each lane is shown below.The traffic flow data which were recorded was used as the input data.

0

2

4

6

8

10

12

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45Upstream Flow Downstream Flow

Figure 4 Upstream and downstream flow for lane 1

0

5

10

15

20

25

30

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45Upstream Flow Downstream Flow

Figure 5 Upstream and downstream flow for lane 2 with additional traffic from JalanLempeng

5.0 Conclusion

This study was carried out to determine the downstream distribution pattern of platoondispersion. The survey was observed located tunnel nosing of Clementi Ave 6 and JalanLempeng junction. The analyses presented in the previous section shows the pattern of thearrival distribution both from minor road and major road. The conclusions can be drawn from

7



the exercise is the accuracy of the speed measurements both of minor road and major road canbe improved if the angle spot camera has 2 spot point (upstream and downstream). The tail ofthe platoon disperse skews to the right. In addition, following recommendations are needed toimprove platoon dispersion study:

It is suggested that further study with other parameters of the vehicle platooncharacteristics such as platoon size and platoon speed should be carried out.

The use of vehicle detectors device also recommended to acquire platoon information.This is because it provides an analytical tool to study various effects of platooncharacteristics under different traffic conditions.

It is necessary to analyze the delay of speed at major road which causes traffic fromminor junction such as Jln Lempeng.

It is suggested that we need consider a Heavy Vehicle which would influenced theplatoon dispersion parameters. This is because the Heavy Vehicle journey time isdifferent with other vehicles.

REFERENCES

Google Earth Pro 5.2. Google.

Highway Capacity Manual. 2000. Special Report 209, 4th Ed., TRB, National ResearchCouncil, Washington, D.C.,

May, A. D. (1990), Traffic Flow Fundamentals, Prentice-Hall, Inc., Englewood Cliffs, N.J.

Traffic Monitoring Guide, 3rd Ed. Federal Highway Administration (FHWA)

Traffic Flow Theory A State-of-the-Art Report (2001). Committee on Traffic Flow Theoryand Characteristics (AHB45). TRB, National Research Council, Washington, D.C.,

8



Appendix 1 Vehicle speed probability normal plot

25 30 35 400.003

0.010.02

0.05

0.10

0.25

0.50

0.75

0.90

0.95

0.980.99

0.997

Data

Pro

babi

lity

Normal Probability Lane 1

20 25 30 35 400.003

0.010.02

0.05

0.10

0.25

0.50

0.75

0.90

0.95

0.980.99

0.997

Data

Pro

babi

lity

Normal Probability Lane 2

9



Appendix 2 Headway distribution of Jalan Lempeng

0%

20%

40%

60%

80%

100%

0

10

20

30

40

50

60

1 2 3 4 5 6 7 8 9 101112131415161718192021222324252627282930

Freq

uenc

y

Time(s)

Jl Lempeng

Actual

CDF

Flow t (min) Lane 3 Lane 4 J Lempeng1 4 5 102 10 10 103 8 6 74 4 5 65 5 4 116 11 6 127 6 7 58 6 18 89 7 10 9

10 6 12 711 7 7 1012 8 15 813 4 5 614 10 22 415 4 4 616 8 7 817 5 18 418 4 5 419 7 7 920 5 13 621 6 8 1122 6 7 923 7 4 924 7 7 1025 6 11 726 11 7 327 7 9 528 5 12 1029 5 11 530 6 8 7

195 270 226

10



Lane 1 g(t) 6.48E-43 4.05E-05 0.277012 0.469297 0.177092 0.052672 0.016565 0.005877 0.00236 0.001058 0.000522 0.000279 0.000159 9.65E-05 6.13E-05 Flow1 4 0.002 10 4 0.003 8 10 4 1.114 4 8 10 4 4.655 5 4 8 10 4 7.626 11 5 4 8 10 4 6.847 6 11 5 4 8 10 4 5.278 6 6 11 5 4 8 10 4 6.719 7 6 6 11 5 4 8 10 4 8.1210 6 7 6 6 11 5 4 8 10 4 6.8311 7 6 7 6 6 11 5 4 8 10 4 6.5312 8 7 6 7 6 6 11 5 4 8 10 4 6.5613 4 8 7 6 7 6 6 11 5 4 8 10 4 6.5014 10 4 8 7 6 7 6 6 11 5 4 8 10 4 7.1015 4 10 4 8 7 6 7 6 6 11 5 4 8 10 4 6.6016 8 4 10 4 8 7 6 7 6 6 11 5 4 8 10 4 6.6017 5 8 4 10 4 8 7 6 7 6 6 11 5 4 8 10 7.1118 4 5 8 4 10 4 8 7 6 7 6 6 11 5 4 8 6.2819 7 4 5 8 4 10 4 8 7 6 7 6 6 11 5 4 6.5220 5 7 4 5 8 4 10 4 8 7 6 7 6 6 11 5 5.3021 6 5 7 4 5 8 4 10 4 8 7 6 7 6 6 11 5.2722 6 6 5 7 4 5 8 4 10 4 8 7 6 7 6 6 5.8323 7 6 6 5 7 4 5 8 4 10 4 8 7 6 7 6 5.6224 7 7 6 6 5 7 4 5 8 4 10 4 8 7 6 7 5.8625 6 7 7 6 6 5 7 4 5 8 4 10 4 8 7 6 6.2526 11 6 7 7 6 6 5 7 4 5 8 4 10 4 8 7 6.7527 7 11 6 7 7 6 6 5 7 4 5 8 4 10 4 8 6.6628 5 7 11 6 7 7 6 6 5 7 4 5 8 4 10 4 7.6329 5 5 7 11 6 7 7 6 6 5 7 4 5 8 4 10 8.7130 6 5 5 7 11 6 7 7 6 6 5 7 4 5 8 4 7.1231 6 5 5 7 11 6 7 7 6 6 5 7 4 5 8 5.7232 6 5 5 7 11 6 7 7 6 6 5 7 4 5 5.5133 6 5 5 7 11 6 7 7 6 6 5 7 4 4.1734 6 5 5 7 11 6 7 7 6 6 5 7 1.4935 6 5 5 7 11 6 7 7 6 6 5 0.4636 6 5 5 7 11 6 7 7 6 6 0.1637 6 5 5 7 11 6 7 7 6 0.0638 6 5 5 7 11 6 7 7 0.0339 6 5 5 7 11 6 7 0.0140 6 5 5 7 11 6 0.0141 6 5 5 7 11 0.0042 6 5 5 7 0.0043 6 5 5 0.0044 6 5 0.0045 6 0.00

195.60

11



Lane 2 g(t) 1.42E-79 1.18E-09 0.071313 0.611157 0.239599 0.049525 0.009925 0.002263 0.000605 0.000189 6.74E-05 2.7E-05 1.2E-05 5.76E-06 2.98E-06 Flow1 15 0.002 20 15 0.003 13 20 15 0.004 11 13 20 15 1.075 15 11 13 20 15 10.596 18 15 11 13 20 15 16.747 12 18 15 11 13 20 15 14.268 26 12 18 15 11 13 20 15 12.059 19 26 12 18 15 11 13 20 15 13.9610 19 19 26 12 18 15 11 13 20 15 16.1811 17 19 19 26 12 18 15 11 13 20 15 14.4012 23 17 19 19 26 12 18 15 11 13 20 15 21.2013 11 23 17 19 19 26 12 18 15 11 13 20 15 20.0114 26 11 23 17 19 19 26 12 18 15 11 13 20 15 18.8415 10 26 11 23 17 19 19 26 12 18 15 11 13 20 15 17.8216 15 10 26 11 23 17 19 19 26 12 18 15 11 13 20 15 20.1117 22 15 10 26 11 23 17 19 19 26 12 18 15 11 13 20 15.1818 9 22 15 10 26 11 23 17 19 19 26 12 18 15 11 13 20.6119 16 9 22 15 10 26 11 23 17 19 19 26 12 18 15 11 14.2420 19 16 9 22 15 10 26 11 23 17 19 19 26 12 18 15 14.6021 19 19 16 9 22 15 10 26 11 23 17 19 19 26 12 18 18.4822 16 19 19 16 9 22 15 10 26 11 23 17 19 19 26 12 12.8323 13 16 19 19 16 9 22 15 10 26 11 23 17 19 19 26 14.5724 17 13 16 19 19 16 9 22 15 10 26 11 23 17 19 19 17.5125 18 17 13 16 19 19 16 9 22 15 10 26 11 23 17 19 18.2526 10 18 17 13 16 19 19 16 9 22 15 10 26 11 23 17 16.4027 14 10 18 17 13 16 19 19 16 9 22 15 10 26 11 23 14.1728 22 14 10 18 17 13 16 19 19 16 9 22 15 10 26 11 15.8329 16 22 14 10 18 17 13 16 19 19 16 9 22 15 10 26 16.6530 15 16 22 14 10 18 17 13 16 19 19 16 9 22 15 10 12.4531 15 16 22 14 10 18 17 13 16 19 19 16 9 22 15 13.6332 15 16 22 14 10 18 17 13 16 19 19 16 9 22 18.6733 15 16 22 14 10 18 17 13 16 19 19 16 9 16.9734 15 16 22 14 10 18 17 13 16 19 19 16 14.2735 15 16 22 14 10 18 17 13 16 19 19 4.6536 15 16 22 14 10 18 17 13 16 19 0.9637 15 16 22 14 10 18 17 13 16 0.2038 15 16 22 14 10 18 17 13 0.0539 15 16 22 14 10 18 17 0.0140 15 16 22 14 10 18 0.0041 15 16 22 14 10 0.0042 15 16 22 14 0.0043 15 16 22 0.0044 15 16 0.0045 15 0.00

488.41

Exercise 3 - Platoon Dispersion Analysis Aditya Nugroho e

Documents

Transcript of Exercise 3 - Platoon Dispersion Analysis Aditya Nugroho e