01504389

Component

http://onlinepubs.trb.org...nces/2011/RSS/1/Gaca,S.pdf

The paper presents the results of analyses of headways between vehicles on road sections, which can be used as an indirect measure of traffic safety. Such an assumption is derived from a classic model of risk, where the number of accidents and collisions is a product of the values of risk exposure and probability of risk events and their severity. Time To Collisions (TTC) and Time available for Driver’s Reaction (TDR) were taken by the authors as indirect measures of risk. To evaluate the TTC the authors used a typical physical model. Deceleration values and lengths of vehicles were adopted in reference to their type (passenger cars and heavy vehicles). The aim of the analysis was to indicate the impact of several factors, not only traffic flow intensity, on the share of unsafe headways between vehicles, which can affect rear-end collision risk. Particular attention was paid to the impact of the following factors on unsafe headways in traffic flow: (1) traffic volume and traffic flow composition and its speed, (2) different drivers’ behaviour at night-time, (3) characteristics of road and road development, (4) random character of drivers’ behaviour, expressed by variability of reaction time. The data coming from measures on 219 road sections in Poland were involved in the evaluation. There were sections of different cross-section types, with different speed limits, and of different localisation (e.g. roads through built-up area, suburban area and rural area). Additionally, entries of intersections and sections of approaches to pedestrian crossings were also taken into account. The analyses did not include the sections on entries to intersections with light signalling, which due to their specific functioning need a separate study, as is presented in foreign literature (Archer, Young, 2009; Cunto, Saccomanno, 2009). The conducted analyses resulted in building up a database, comprising records of traffic parameters for over 2.6 million vehicles. 24-hour measurements (automatic traffic recorders) covered: time of vehicle’s appearance, speed and length of vehicles. The paper introduces a possible method of assessing the probability of rear-end collision occurrence.

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01501394

English

22p

2011

3rd International Conference on Road Safety and Simulation

Digital/other

Figures; References; Tables

Behavior; Drivers; Headways; Reaction time; Rear end crashes; Traffic safety; Traffic volume

Time to collision

Poland

Highways; Safety and Human Factors; I83: Accidents and the Human Factor

TRIS, TRB, ATRI

Jan 9 2014 12:30PM