Urban Expressway Speed Spatial Inconsistency and Its Effect on Safety
Accidents on urban expressways lead to large external costs due to the process effects of congestion; and the reduction of its influence is a main objective for traffic management. The speed difference between the adjacent positions along the road, called speed spatial inconsistency, is a potential risk factor which is less studied because of data limitation. It may be one of the substantial causes of crashes on urban expressways. Thanks to the floating car data (FCD) generated by the global positioning systems (GPS), which are installed in taxis, we can acquire detailed speed data along a road by viewing taxis as probe vehicles instead of isolated loop-detectors. The objective of this study is to explore the relationship between crash frequency and speed spatial inconsistency on urban expressways while controlling for other relevant factors. To accomplish this objective, the authors chose 174 segments that belonged to the four main urban expressways of Shanghai where tracks are prohibited in the analysis time. Meanwhile, more than 45,000 taxis' FCD with 10 seconds fixed time interval were obtained, and a series of indicators to speed spatial inconsistency were developed. Also, the relevant crash data, traffic data and road characteristics data were collected. After that, Bayesian Poisson-gamma models were established for the frequencies of total crash, rear-end, and sideswipe collisions. The results suggest that larger speed spatial inconsistency for a road segment leads to more crashes and each factor has the same positive or negative effects on the three kinds of frequencies.
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Supplemental Notes:
- This paper was sponsored by TRB committee ANB20 Safety Data, Analysis and Evaluation
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Corporate Authors:
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Washington, DC United States 20001 -
Authors:
- Xu, Chuan
- Wang, Xuesong
- Chen, Xiaohong
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Conference:
- Transportation Research Board 91st Annual Meeting
- Location: Washington DC, United States
- Date: 2012-1-22 to 2012-1-26
- Date: 2012
Language
- English
Media Info
- Media Type: Digital/other
- Features: Figures; References; Tables;
- Pagination: 19p
- Monograph Title: TRB 91st Annual Meeting Compendium of Papers DVD
Subject/Index Terms
- TRT Terms: Floating car data; Highway safety; Probe vehicles; Traffic crashes; Traffic speed; Urban highways; Vehicle spacing
- Subject Areas: Highways; Safety and Human Factors; I80: Accident Studies;
Filing Info
- Accession Number: 01373618
- Record Type: Publication
- Report/Paper Numbers: 12-2001
- Files: TRIS, TRB
- Created Date: Jun 25 2012 9:48AM