A Driving Simulation Based Study on the Effects of. Road Marking Luminance Contrast on Driving Safety. Yong Cao, Jyh-Hone Wang

Transcription

1 A Driving Simulation Based Study on the Effects of Road Marking Luminance Contrast on Driving Safety Yong Cao, Jyh-Hone Wang Department of Industrial and Manufacturing Engineering University of Rhode Island, Kingston, RI Sponsored by Rhode Island Department of Transportation

2 Outlines Introduction Methodology Results and Analysis Conclusion

3 Introduction Road markings serve to regulate, guide, and channelize traffic and supplement other traffic-control devices. Drivers rely more on retroreflective road marking during nighttime than daytime.

4 Introduction - Road Marking Colors and Configurations

5 Introduction - Road Marking Luminance Contrast It is the ratio of the luminance difference between a road marking and its pavement background to the pavement background luminance. It is an important factor that could affect drivers response. The visibility of road markings deteriorates over time due to weather, traffic wear, and maintenance operation.

6 Introduction - Objectives Investigate the effects of luminance contrast of road marking on drivers responses. Investigate the demographic impact on drivers responses. Recommend the timing of repair or repaint on road markings based on its luminance contrast condition.

7 Methodology - Experiment Design The factors and levels in the experiment

8 Methodology - Experiment Design The subjects 36 subjects were recruited. Gender - 18 males, 18 females. Age - 12 in 20~40 yrs. age group, 12 in 41~60 yrs. age group, & 12 in > 60 yrs. Age group. All had driving experience on interstate highways and were currently holding valid RI driver s licenses.

9 Methodology - Experiment Design The statistical model T = µ + C + S + C S + A + G + A G + ε where: T subjects response time in second; µ overall mean, in second; C road marking luminance contrast; S driving speed, in mph; A subjects age; G subjects gender; ε error.

10 Methodology - Experiment Design Number of runs per subject: (4 marking types 5 luminance levels 2 driving speed) 3 Repetitions = 120 Approximate experiment time per subject 15 sec./run * 120 = 1,800 sec. = 30 min.

11 Methodology - Experiment Procedure A sequence of digital night driving videos is projected onto a screen. Four different types of road markings are presented in the video. Subject sitting in a car sees the road marking appears from far end. An appropriate action (pressing predetermined key) is required to signal subject s comprehension. Subjects response time and accuracy are recorded in the MS Access database.

12 Methodology - Experiment Setup

13 Methodology - Video Stimuli Four marking configurations used in the experiment White single White single Yellow skip & Yellow double skip line solid line solid lines solid lines

14 Methodology - Video Stimuli The five levels of road marking luminance contrast Level 1 (-30%) Level 2 (-15%) Level 3 (original) Level 4 (+15%) Level 5 +30%)

15 Methodology - Video Stimuli Still images of a 10-second video Start 5th second 7th second

16 Methodology - Field Measurements Road marking luminance contrast levels and values

17 Results and Analysis - The ANOVA table on Response Time ANOVA based on response time for white single skip marking

18 Results and Analysis - The ANOVA table on Response Time ANOVA based on response time for white single solid marking

19 Results and Analysis - The ANOVA table on Response Time ANOVA based on response time for yellow skip and solid marking

20 Results and Analysis - The ANOVA table on Response Time ANOVA based on response time for yellow double solid marking

21 Results and Analysis - Main Effect Plots w.r.t. Response Time Main effect plots for white single skip marking Main effect plots for white single solid marking

22 Results and Analysis - Main Effect Plots w.r.t. Response Time Main effect plots for yellow skip & solid marking Main effect plots for yellow double solid marking

23 Results and Analysis - The White Marking Threshold Luminance Contrast When y = f (x) = 0, x = 1.1 = the white marking threshold luminance contrast

24 Results and Analysis - The Yellow Marking Threshold Luminance Contrast y = 0.05x x x R 2 = Average Response Time (second) Average Response Time (second) y = x x x R 2 = Marking Luminance Contrast Marking Luminance Contrast The yellow marking threshold luminance contrast = 3.3~

25 Conclusion Subjects response time drop with the increment of road marking luminance contrast, but at different rates in different contrast segments. White markings are more visible than yellow markings. Driving at higher speed get faster responses. Older subjects take the longest responses while younger subjects take the least. Female subjects respond a little bit slower than males. The threshold luminance contrast values for white and yellow road marking are estimated to be 1.1 and 3.3~3.5 respectively. When road markings contrast values are below these thresholds, a repair or repaint on road markings might be needed.

26 Final Remarks The above conclusions are based on the driving simulation experiment under lowbeam headlight at night on dry straight and flat road conditions. Many other factors, such as road marking width, location, material, road alignment, and weather were not considered in this study. To better understand the effects of road marking luminance contrast on driving safety under these factors, further studies that can better simulate real driving scenario are required.

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