Shun-Hui Chang, Chih-Yung Lin, Chun-Chia Hsu, Chin-Ping Fung, Jiun-Ren Hwang 報告者：楊子群 The effect of a collision warning system on the driving performance

Shun-Hui Chang , Chih-Yung Lin , Chun-Chia Hsu , Chin-Ping Fung , Jiun-Ren Hwang

報告者：楊子群

The effect of a collision warning system on the driving performance of young drivers at intersections

Participants

Investigated the driving performance of young drivers at intersections while driving a vehicle that was equipped with different ICWSs.(A driving simulator was employed in order to simulate an intersection accident that resulted from a violator’s vehicle running a red light. )

Goal References Method Results & Discussion

Participants


researcher content

NPA (2007) In the Taiwan => 39% of intersections.

Elvik & Vaa (2004) In the Norway => 40% of intersections.

FHWA (2007)In the United States => 1)21% of fatalities occurred at intersections2)40–45% of intersection or intersection-related crashes.

Retting, Williams, Preusser, and Weinstein (1995)

22% of urban accidents result from drivers failing to halt at traffic controls.

FHWA (2005) In United States => Crashes that were caused by running a red light resulted in an estimated 805 (8.75%) fatalities

交通部 (2007) In Taiwan => running a red light has been one of the top five causes of traffic accidents in recent years

Lawrence (2003); Maycock, Lockwood, & Lester (1991); Monarrez-Espino, Hasselberg, & Laflamme (2006); Vernick et al. (1999); Waller, Elliott, Shope, Raghunathan, & Little (2001); Yokota, Haga, Ogawa, & Kokubun (2003)

Age and experience of young drivers affect their driving behaviors, which correspondingly bring about a higher risk in driving.

Participants


researcher content

Triggs & Smith (1996)

Young driver more high accidents rate than other group.

Engstrom, Gregersen, Hernetkoski, Keskinen, & Nyberg (2003)

Evans (1991)

BCC (2008)

NSW (2008)

MOT (2008)

DOH (2007)

Male more high accidents rate than female.BCAA (2008)

Kweon & Kockelman (2003)

Santokh (2003)

Participants

30 male subjects.

Age : 20~25 years. (Average age : 23.1 years)

Driver’s license at least 2 years.

Average number of driving days per week was around two.


Apparatus

Driving simulator :Six-degree-of-freedom Stewart motion platform.Virtual-reality-based visual and audio system.

Vehicle motion simulation software.

Computer

Scene is updated at rates between 25 and 35 Hz.


Experimental design

Host vehicle was equipped with a collision avoidance warning system.Three conditions of the warning system : 　－ beeping　　　“ bi-bi”　　　 2khz and 70 db.　－ speech message　　　“ watch your left-hand(right-hand) side”　－ null signal

Violation at a Seed of 70 km/h at a blind intersection from the left or right direction.Host vehicle at a seed of 50 km/h.


Experimental design

Two way, two-lane road, with 3.5-m-wide lanes and 1-m-wide pedestrian sidewalks.　 accelerating section (300 m)　 experimental section(5100 m)　 / located every 400–600 m in the experimental section /

　 braking section (900 m) 10–15 vehicles including automobiles, motorcycles 　 and pick-up trucks. The field of view for the drivers was about 56 。　 at 　 the specified position.


Procedure

[ Step1 ] Subjects were asked to provide personal information.　　　　　 (gender, age and driving experience)

[ Step2 ] Experimental instructions.

[ Step3 ] Experimental practice.(20-25 min)

[ Step4 ] Formal experiment.(7-10 min)


Data collection and statistical analysis

reaction timeSpeedlateral position deviation accident ratesAll data were collected at 30 Hz.

driving performance => Multivariate analysis of variance (MANOVA)　 different ICWS content.

　 direction of the violator’s vehicle.

　 location of intersection accident.

　 number of driving days per week.

post-hoc testing => Tukey’s honesty significant difference (HSD).Accident rate=>chi-square test and path analysis.


Driving performance – Reaction time(1/2)

A statistical difference was the three kinds of warning systems (F = 6.394, df = 2, p = 0.003)

　 for the reaction time.　 Tukey’s HSD:

The average reaction time at the first intersection was significantly longer than the time 　 at the non-first intersection(F = 5.765, df = 1, p = 0.019).

type mean Post hoc

Beep 1.38 A

Speech message 1.45 A 　 B

Null signal 1.73 　　 B

type mean Post hoc

Non-first intersection 1.34 A

First intersection 2.03 　　 B


Driving performance – Reaction time(2/2)

average reaction time taken by drivers who drove more than 1 day per week and drove 　 less than 1 day per week was not statistically significant(F = 0.238, df = 1, p = 0.628).

There were no interaction( 交互 ) between any two traffic factors of the ICWS audio signals,　 the locations of intersection accidents and the number of driving days per week.

Discussion-reaction time

Suggested pay more attention when they enter an intersection than when they drive on a　 straight roadway.


Driving performance – Seed(1/3)

Mean seed Mean speed did not reach statistical significance among the three ICWS conditions (F = 1.95, df = 2, p = 0.151).

mean speed at the first intersection was significantly higher than the speed at the non-　 first intersection (F = 7.36, df = 1, p = 0.009).

The number of driving days per week did not have a significant effect on the mean speed.



Standard deviation of speed

Standard deviation of speed among the three ICWS conditions reached statistical 　 significance (F = 3.44, df = 2, p = 0.038).

The standard deviation of speed between the first and non-first intersection was not 　 statistically significant difference.

The number of driving days per week did not have a significant effect on the standard 　 deviation of speed.



Discussion-seed

1)A high driving speed may require a longer brake time in order to avoid an accident.

2)When drivers were not aware of any violator vehicles at an intersection and maintained a high driving speed, their reaction time was long.


Driving performance – Lateral position deviation

There were no significant differences in the lateral control over the host vehicle among the three ICWS conditions.


Driving performance – Accident rate(1/4)

Accident rate = The number of violator intersections in which the ICWS system did not generate a signal

Number of accidents Beep warning : 16% Speech warning message : 26% no signal : 44% Statistically significant (χ2 = 8.294,p = 0.016) among the different ICWS conditions:

With regard to the violator’s direction( 方向 ), the violator vehicle was not statistically significant.

Type % Post hoc

Beep warning 16 A

Speech message 26 A 　Null signal 44 　　 B



First intersection and non-first intersection was statistically significant (χ2 = 13.12, p = 0.000).

Participants driving experience was statistically significant difference (χ2 = 4.35, p = 0.037).

Type % Post hoc

Non-first intersection 19 A

First intersection 53 B 　

Type % Post hoc

More than 1 day per week 24 A

Less than 1 day per week 47 B 　



Path Analysis:violator’s direction and lateral position deviation were not significant to the intersection accidents.



Discussion-accident rate

1) If the driver noticed in advance that the violator, the reaction time would be reduced, and the subject would have more time to manage the traffic event. 　　　　　　　 (Accident rate was reduced from 44% to 26% or 16%)

2) Young and less-experienced drivers are in a high risk category.

3) In this study, there was a higher accident risk at the first intersection.

4) There was a higher accident risk at the first intersection.


Limitations

駕駛模擬無法模擬出如真實環境的複雜度，例如 : 嚴重車禍 ( 車輛翻轉 ) 、車輛撞到時的感受等。


Documents

Shun-Hui Chang, Chih-Yung Lin, Chun-Chia Hsu, Chin-Ping Fung, Jiun-Ren Hwang 報告者：楊子群 The effect of a collision warning system on the driving performance