00625321

Component

http://onlinepubs.trb.org...trr/1992/1356/1356-002.pdf

https://scholar.google.co...lton&publication_year=1992

The purpose was to (a) determine the horizontal curve features that affect accident experience on two-lane rural roads, (b) determine which types of geometric improvements on curves will affect accident experience, and (c) develop accident reduction factors based on these findings. Very little of this information has been available to highway safety engineers and designers. The results were based on an analysis of 10,900 horizontal curves in Washington State with corresponding accident, geometric, traffic, and roadway data variables. Statistical modeling revealed significantly higher curve accidents for sharper curves, narrower curve width, lack of spiral transitions, and increased superelevation deficiency. All else being equal, higher traffic volumes and longer curves were also associated with significantly higher curve accidents. Ranges of accident reductions for horizontal curves improvements were determined for flattening curves, widening lanes, widening paved shoulders, adding unpaved shoulders, adding a spiral transition, and improving superelevation. From the study findings, a variety of improvements were recommended for horizontal curves with moderate and sharp curvature, and upgrading specific roadside improvements. Expected costs should be compared with estimated accident reductions to determine whether geometric improvements are warranted.

This paper appears in Transportation Research Record No. 1356, Operational Effects of Geometrics and Geometric Design. 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

01404971

English

p. 11-19

1992

Transportation Research Record

0309052203

Figures (2) ; References (11) ; Tables (3)

Crashes; Curvature; Curves (Geometry); Geometric design; Highway safety; Improvements; Recommendations; Roadside improvement; Rural highways; Safety; Spirals; Superelevation; Traffic safety; Transition curves; Two lane highways

Horizontal curvature

Washington (State)

Design; Highways; Planning and Forecasting; Research; Safety and Human Factors; I21: Planning of Transport Infrastructure; I82: Accidents and Transport Infrastructure

TRIS, TRB, ATRI

Nov 16 1993 12:00AM

• COMPARISON OF OPERATIONAL PARAMETERS FOR CONVENTIONAL AND SINGLE-POINT DIAMOND INTERCHANGES
• GEOMETRIC INCONSISTENCIES AND ACCIDENT EXPERIENCE ON TWO-LANE RURAL HIGHWAYS
• GUIDELINES FOR OFFSETTING OPPOSING LEFT-TURN LANES ON FOUR-LANE DIVIDED ROADWAYS
• MITIGATION OF SIGHT-DISTANCE PROBLEM FOR UNPROTECTED LEFT-TURNING TRAFFIC AT INTERSECTIONS
• OPERATIONAL EFFECTS OF NONTRAVERSABLE MEDIANS AND TWO-WAY LEFT-TURN LANES: A COMPARISON
• OPERATIONAL IMPACTS OF WIDER TRUCKS ON NARROW ROADWAYS
• RATIONAL APPROACH FOR GEOMETRIC DESIGN OF SPEED-CONTROL ROAD HUMPS
• ROADWAY DESIGN STANDARDS TO ACCOMMODATE LOW-CLEARANCE VEHICLES (WITH DISCUSSION AND CLOSURE)
• SIGHT-DISTANCE DESIGN FOR CURVED ROADWAYS WITH TANGENTIAL INTERSECTIONS