The phenomenon of high-speed-car-following on Chinese highways

The phenomenon of high-speed-car-followingon Chinese highways

Mingmin Guo, Zheng WuDepartment of Mechanics and Engineering Science

Fudan University

ICNM-VI——The phenomenon of high-speed-car-following on Chinese highways

25-2

Outline

Background and motivation

Data Sets

Results and analysis

Conclusions


25-3


Traffic flow is of complicated nonlinearity: stop-and-

go phenomenon under high density.

We found the nonlinearity under low density on urban

expressways: high-speed-car-following (HSCF).


25-4

Background and motivation Similar results in literatures

German highway A1, loop detector data

Neubert et al., PRE 1999, 60(6) : 6480-6490

U.S. highway 101, NGSIM dataChen et al., IEEE Trans. Intell. Transp.

2010: 11(4) : 773-785


25-5


Empirical observations play crucial roles. Numerous important achievements

Next Generation Simulation (NGSIM) project

The traffic videos taken from the intercity highways

are lacking.

So we studied the HSCF phenomenon on intercity

highways based on traffic videos.


25-6

Outline


Data Sets


Conclusions


25-7

Data Sets

100 hours of traffic video from fours locations


25-8

Data Sets Seven samples from 17.5 hours out of total videos

About 40,000 vehicles94392 speed data、 28201 space headway data

Table 1. Data samples

Sample Highway Shooting location Lanes Shooting time

Number of vehicles

Sample size Speed Headway

1 G2

West of Shanghai Jiangqiao toll gate (NU) 4

2012/04/03 14:45-16:12 4284 6203 1909

2 G2 2012/05/04 15:06-16:36 4914 8540 2243

3 G2 2012/06/06 07:47-11:49 11588 42556 7644

4 G15w On both sides of Jiaxing

Xiangxian Bridge (FU) 2 2012/03/28 08:01-09:43 1387 2731 514

5 G15w 2012/09/08 08:08-09:59 1652 2958 528

6 G45 North of Beijing Shaoyaoju subway station (NU) 2 2011/07/07 15:43-17:55 ---- 14402 14402

7 G60 South of Jiaxing Wangdian service area (FU) 4 2011/07/26 14:14-18:12 4357 17002 961

1


25-9

Data Sets The vehicle class was collected.

The proportions of heavy vehicles of two frequently-

used NGSIM dataI-80 (Berkeley Highway): 2.2%US-101 (Hollywood Freeway): 3.8%

Sample Car Truck Number Proportion Number Proportion

3 (09:37-11:24) 3596 77.15% 1065 22.85% 4 950 68.49% 437 31.51% 7 3269 75.03% 1088 24.97%

1


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Data Sets

Overview of the traffic situation

1

Sample Highway Average speed (m/s) Average space headway (m)

Total Lane 1 Lane 2 Lane 3 Lane 4 Total Lane 1 Lane 2 Lane 3 Lane 4

1 G2 26.6 26.9 26.8 26.6 25.2 33.8 32.0 34.4 35.8 39.0

2 G2 26.0 27.4 27.1 24.4 22.8 36.1 35.0 36.3 37.4 41.7

3 G2 24.5 26.5 25.8 22.7 21.5 38.4 37.1 37.2 41.8 44.1

4 G15w 25.6 27.1 23.6 --- --- 37.3 35.4 43.5 --- ---

5 G15w 26.0 27.5 23.8 --- --- 35.3 34.7 38.7 --- ---

6 G45 16.8 16.0 17.7 --- --- 40.9 38.6 43.1 --- ---

7 G60 26.3 30.7 28.8 21.8 19.7 39.9 39.2 38.4 46.1 40.8


25-11

Outline


Data Sets


Conclusions


25-12


Time headway (ht): the time difference between two

successive vehicles passing the same location.

In this paper, it was calculated by

,st

hhv

where hs is space headway, v is speed.


25-13


The percentages of ht ≤ 2 s and ht ≤ 1 s are remarkable.

Sample Highway Total number of vehicles

Time headway ≤ 1 s

Time headway ≤ 2 s

Number of vehicles Proportion Number of vehicles Proportion

1 G2 4284 498 11.62% 1348 31.47%

2 G2 4914 429 8.73% 1403 28.55%

3 G2 11588 899 7.76% 2413 20.82%

4 G15w 1387 80 5.77% 289 20.84%

5 G15w 1652 115 6.96% 322 19.49%

6 G45 14402 948 6.58% 6598 45.81%

7 G60 4357 122 2.80% 394 9.04%

1


25-14


The small ht are related to the driving behavior with

high speed and small spacing, so-called “high-speed-

car-following”.

Frequency distribution of the data with ht≤1 s in

sample 3 for different speed ranges

10 15 20 25 30 35 400

100

200

300

400

Speed (m/s)

Freq

uenc

y


25-15


The distributions of HSCF vehicles on each lane are

different.

Proportion of the vehicles with ht≤1 s in

sample 3 for each lane

Most of the HSCF

vehicles are cars.


25-16

Results and analysis Dependence of the average speed at different lanes on

the number of HSCF vehicles----in 1 min interval

0 1 2 3 4 5 6 720

25

30

HSCF (veh)

Vel

ocity

(m/s

)

Lane 1Lane 2Lane 3Lane 4

0 1 2 3 4 520

25

30

HSCF (veh)

Vel

ocity

(m/s

)

Lane 1Lane 2

Sample 3, G2

Sample 5, G15w


25-17

Results and analysis Dependence of the flow at different lanes on the

number of HSCF vehicles----in 1 min interval

Sample 3, G2

Sample 5, G15w

0 1 2 3 4 5 6 70

500

1000

1500

2000

HSCF (veh)

Flow

(veh

/h)


0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 50

500

1000

1500

2000

HSCF (veh)

Flow

(veh

/h)

Lane 1Lane 2


25-18

Results and analysis Dependence of the density at different lanes on the

number of HSCF vehicles----in 1 min interval

Sample 3, G2

Sample 5, G15w

0 1 2 3 4 5 6 70

5

10

15

20

HSCF (veh)

Den

sity

(veh

/km

)


0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 50

5

10

15

20

HSCF (veh)

Den

sity

(veh

/km

)

Lane 1Lane 2


25-19

Results and analysis HSCF can roughly be classified into two types:

Active HSCF Passive HSCF


25-20

Results and analysis HSCF often makes the rear vehicle’s driver take a

lane-changing

maneuver as well.


25-21

Results and analysis Dependence of the average frequency of lane-

changing at different lanes on the number of HSCF

vehicles----in 1 min interval

0 1 2 3 4 5 6 70

1

2

3

4

5

HSCF (veh)

Lane

cha

ngin

g (v

eh)



25-22

Outline


Data Sets


Conclusions


25-23

Conclusions

HSCF, such a dangerous driving behavior, has a

relatively high frequency of occurrence on Chinese

intercity highways.

Cars, fast lanes and locations near the urban area

have higher proportion of HSCF than trucks, slow

lanes and locations far from the urban area,

respectively.


25-24

Conclusions

In general, the flow and the density will increase as

the frequency of HSCF increases. HSCF may affect

the capacity and level of service.

As the frequency of HSCF increases, the average

velocity of the left lane decreases, while the average

velocity of the other lanes increases.


25-25

Conclusions

HSCF can be classified into active type and passive

type. The latter type is caused by lane-changing and

overtaking.

HSCF may cause lane-changing as well, and the

frequencies of them vary synchronously.

HSCF enhances the nonlinearity of traffic flow under

low density.


Thank you!


In sample 3 (09:37-11:24)

258 cars with ht ≤ 1s were observed.

13 trucks with ht ≤ 1s were observed.

Among the 258 HSCF cars, only 2 of them followed

trucks.

Among the 13 HSCF trucks, more than a half, i.e. 7 of

them, travelled after cars.

Appendix-1


Appendix-2

The time series of the flow, the density and the velocity of sample 3

0 50 100 150 200 2500

500

1000

1500

2000

Flow

(veh

/h)

0 50 100 150 200 25040

60

80

100

120

Vel

ocity

(km

/h)

0 50 100 150 200 2500

5

10

15

20

Time (min)

Den

sity

(veh

/km

)



Appendix-3

The fundamental diagram of sample 3----in 1 min interval

0 2 4 6 8 10 12 14 16 18 200

500

1000

1500

2000

Density (veh/lane)

Flow

(veh

/h)

Lane 1

0 2 4 6 8 10 12 14 16 18 200

500

1000

1500

2000

Density (veh/lane)

Flow

(veh

/h)

Lane 2

0 2 4 6 8 10 12 14 16 18 200

500

1000

1500

2000

Density (veh/lane)

Flow

(veh

/h)

Lane 3

0 2 4 6 8 10 12 14 16 18 200

500

1000

1500

2000

Density (veh/lane)

Flow

(veh

/h)

Lane 4


Appendix-4

The fundamental diagram of sample 3---- based on the moving average of 15-min period

0 5 10 150

500

1000

1500

Density (veh/km)

Flow

(veh

/h)

Lane 1

0 5 10 150

500

1000

1500

Density (veh/km)

Flow

(veh

/h)

Lane 2

0 5 10 150

500

1000

1500

Density (veh/km)

Flow

(veh

/h)

Lane 3

0 5 10 150

500

1000

1500

Density (veh/km)

Flow

(veh

/h)

Lane 4


Appendix-5

The trends of the flow and the HSCF----based on the moving average of 15-min period

0 50 100 150 200 2500

500

1000

1500

Time (min)

Lane 1

0 50 100 150 200 2500

500

1000

1500

Time (min)

Lane 2

0 50 100 150 200 2500

500

1000

1500

Time (min)

Lane 3

0 50 100 150 200 2500

500

1000

1500

Time (min)

Lane 4

flowfrequency of HSCF(×10)




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The phenomenon of high-speed-car-following on Chinese highways