00818857

Component

https://doi.org/10.3141/1751-01

http://scholar.google.com...Lord&publication_year=2001

Modern roundabouts are designed to control traffic flow at intersections without the use of stop signs or traffic signals. U.S. experience with modern roundabouts is rather limited to date, but in recent years there has been growing interest in their potential benefits and a relatively large increase in roundabout construction. This interest has created a need for data regarding the safety effect of roundabouts. Changes in motor vehicle crashes following conversion of 23 intersections from stop sign and traffic signal control to modern roundabouts are evaluated. The settings, located in seven states, are a mix of urban, suburban, and rural environments with the urban sample consisting of both single-lane and multilane designs and the rural sample consisting of only single-lane designs. A before-after study was conducted using the empirical Bayes procedure, which accounts for regression to the mean and traffic volume changes that usually accompany conversion of intersections to roundabouts. For the 23 intersections combined, this procedure estimated highly significant reductions of 40% for all crash severities combined and 80% for all injury crashes. Reductions in the numbers of fatal and incapacitating injury crashes were estimated to be about 90%. In general, the results are consistent with numerous international studies and suggest that roundabout installation should be strongly promoted as an effective safety treatment for intersections. Because the empirical Bayes approach is relatively new in safety analysis, the potential of this methodology in the evaluation of safety measures is demonstrated.

This paper appears in Transportation Research Record No. 1751, Geometric Design and the Effects on Traffic Operations 2001.

English

p. 1-8

2001

Transportation Research Record

0309072123

References (19) ; Tables (8)

Bayes' theorem; Before and after studies; Empirical methods; Fatalities; Injuries; Regression analysis; Roundabouts; Rural areas; Suburbs; Traffic crashes; Traffic safety; Urban areas

United States

Data and Information Technology; Design; Highways; Safety and Human Factors; I82: Accidents and Transport Infrastructure

TRIS, TRB, ATRI

Oct 18 2001 12:00AM

• APPLICATION OF ARTIFICIAL NEURAL NETWORKS TO PREDICT SPEEDS ON TWO-LANE RURAL HIGHWAYS
• CONTROLS FOR HORIZONTAL CURVE DESIGN
• DESIGN FACTORS THAT AFFECT DRIVER SPEED ON SUBURBAN STREETS
• GEOMETRIC DESIGN AND SAFETY ASPECTS OF ROUNDABOUTS
• GUIDELINES FOR OPPOSING LEFT-TURN LANE-LINE WIDTHS
• OPERATING SPEED PREDICTION ON CREST VERTICAL CURVES OF RURAL TWO-LANE HIGHWAYS IN NEBRASKA
• OPERATIONAL EVALUATION OF FREEWAY RAMP DESIGN
• SPEED BEHAVIOR ANALYSIS AT CURVED RAMP SECTIONS OF MINOR INTERCHANGES
• SPEED PREDICTION MODELS FOR TRUCKS ON TWO-LANE RURAL HIGHWAYS
• TRAVEL TIME COMPARISONS BETWEEN SEVEN UNCONVENTIONAL ARTERIAL INTERSECTION DESIGNS