00391638

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http://onlinepubs.trb.org...s/trr/1984/960/960-001.pdf

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The complex relationships among several geometric design elements and accidents on two-lane rural roads were studied. Two data sets were used in modeling effects of traffic volume greater than 2,000 vehicles per day, driveway and intersectional conflict frequency, roadside obstacle characteristics and geometric design elements on total accident occurrence for a national data set, and off-road accident frequency and severity for a Michigan route data set. Geometric design elements were aggregated into bundles or groups that are actually found in the field as a result of design policies. Advanced multivariate techniques were used to study these interactions. It was found that accidents interact in such a complex way with traffic volume that use of the conventional vehicle mile exposure rate in modeling is less fruitful than treating average daily traffic (ADT) as an independent variable. For the prediction of accidents, the effects of ADT were found to be most important followed by driveway and intersection density and the geometric elements. The interactive effect of access point density with volume was also important, as was the interactive effect of access point density and geometric characteristics. Longitudinal alignment elements were found to dominate in off-road accident prediction for rural two-lane roads at ADT values of 4,000 vehicles per day or less, whereas roadside elements were of more importance at higher ADT values. No significant independent effects of cross-sectional elements were found in the total accident prediction. Off-road injury accident prediction on rural two-lane highways was more sensitive to roadside obstacle location and characteristics than total accident prediction. Simple categorical models developed from this research explained 63 percent of the total accident variance in the national data set and 54 percent of the off-road accident variance in the other.

Publication of this paper sponsored by Committee on 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.

00396899

HS-038 208

pp 1-13

1984

Transportation Research Record

63rd Annual Meeting of the Transportation Research Board

0309037069

Print

Figures (8) ; References (28) ; Tables (13)

All terrain vehicles; Average daily traffic; Crash rates; Driveways; Forecasting; Geometric design; Hazards; Highway design; Highway safety; Intersections; Mathematical models; Obstructions (Navigation); Roadside; Rural highways; Traffic crashes; Traffic volume; Two lane highways; Vehicle miles of travel

Models

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

HSL, TRIS, TRB

Aug 31 1985 12:00AM

• AN IMPROVED BRIDGE SAFETY INDEX FOR NARROW BRIDGES
• DRIVING DYNAMIC CONSIDERATIONS: A COMPARISON OF GERMAN AND AMERICAN FRICTION COEFFICIENTS FOR HIGHWAY DESIGN
• EFFECT OF TRAFFIC AND GEOMETRIC MEASURES ON HIGHWAY AVERAGE RUNNING SPEED
• STUDY OF THE EFFECT OF TWO-WAY LEFT-TURN LANES ON TRAFFIC ACCIDENTS
• SURVEY OF STATES' R-R-R PRACTICES AND SAFETY CONSIDERATIONS