00492058

Component

http://onlinepubs.trb.org...trr/1989/1213/1213-009.pdf

https://scholar.google.co...raju&publication_year=1989

One of the major factors that should be considered in selecting the speed limit for a stretch of highway is safety. It is generally accepted that the level of safety depends on certain characteristics of the traffic stream and the geometric alignment of the highway. However, in many cases speed limits are posted without adequate consideration given to these characteristics. For example, an important traffic characteristic that influences safety is speed variance. Currently, little is known about the factors that affect the variance of vehicle speeds in a traffic stream. Presented in this paper are the results of a study that investigated the influence of different traffic engineering factors on speed variance and quantified the relationship between speed variance and accident rates. A major influence on speed variance is the difference between the design speed and the posted speed limit. It was determined that speed variance will approach minimum values if the posted speed limit is between 5 and 10 mph lower than the design speed. Outside this range, speed variance increases with an increasing difference between the design speed and the posted speed limit. It was also found that drivers tend to drive at increasing speeds as the roadway geometric characteristics improve, regardless of the posted speed limit, and that accident rates do not necessarily increase with an increase in average speed but do increase with an increase in speed variance.

This paper appears in Transportation Research Record No. 1213, Human Performance and Highway Visibility: Design, Safety, and Methods. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved

01414055

p. 64-71

1989

Transportation Research Record

0309048095

Figures (6) ; References (7) ; Tables (6)

Behavior; Crash rates; Design speed; Drivers; Geometric design; Highway safety; Motor vehicles; Speed; Speed limits; Traffic speed; Variance

Design; Highways; Operations and Traffic Management; Safety and Human Factors; I73: Traffic Control; I82: Accidents and Transport Infrastructure; I83: Accidents and the Human Factor

TRIS, TRB, ATRI

Mar 31 1990 12:00AM

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