01025770

Component

Highway engineers have been interested in the safety aspects of roadway design since the inception of transportation engineering. Conventionally, to evaluate the level of safety for an existing highway facility, the most practicable measure is historical accident records or, for a proposed facility, prediction of accident rates. Since at-grade intersections are the most likely areas of the highway network to experience higher accident rates because of the presence of conflict points, intersections deserve considerable attention from highway engineers in the study of safety issues. Roundabouts are becoming acceptable as a feasible alternative to other types of at-grade intersections. This growing attention is due to their distinct advantages with respect to safety and smooth traffic movement, especially for moderate levels of traffic flow. Many statistical approaches have been used to estimate the effect of variables such as vehicular flow, road or intersection geometry, and environmental features on traffic accident frequencies. Since accidents are rare, random discrete events, they are expected to follow the Poisson phenomenon. A review of previous studies reveals also that the most likely statistical distributions to describe accident occurrences are the Poisson and negative binomial distributions. In this paper, the focus is on the development of an accident prediction model to enable engineers and designers to appreciate the effects of different design features of roundabouts. Accidents that occurred at several roundabouts in Bahrain over the period 1991-2002 are analyzed. The different geometric and traffic characteristics are used as the input parameters in the model to estimate their significance for traffic safety at roundabouts. The GLIM statistical package is utilized to develop a statistical model that relates these characteristics with the level of safety.

01020180

06-1684

English

27p

2006

Transportation Research Board 85th Annual Meeting

CD-ROM

Appendices; Figures; References; Tables

Crash rates; Crash records; Highway design; Highway safety; Intersections; Poisson distributions; Roundabouts; Safety engineering; Traffic circles; Traffic safety; Vehicle safety

Bahrain

Highways; Planning and Forecasting; I20: Design and Planning of Transport Infrastructure

Transportation Research Board Annual Meeting 2006 Paper #06-1684

TRIS, TRB

Mar 3 2006 10:45AM