00758008

Component

http://onlinepubs.trb.org/onlinepubs/sr/sr254.pdf

This paper reviews studies relevant to the causal relationship between speeding and crashes. The conclusions from this study are as follows: (1) There is ample, but not unequivocal, evidence to indicate that, on a given road, crash involvement rates of individual vehicles rise with their speed of travel. (2) There are no convincing data to demonstrate that, across all roads, crash involvement rates rise with the average speed of traffic. This is probably because the average traffic speed is highly correlated with the design speed of different road classes (and other conditions). (3) The absolute speed deviation of crash-involved vehicles from the average traffic speed appears to be positively related to crash probability, especially for rural arterial highways and Interstate highways. (4) The principal factor that accounts for the effects of speed deviation is the requirement to slow down to make turns and to enter and exit high-speed roads. Still, even when the effects of turning vehicles are removed from the data, some effects of speed deviation, especially at the extreme ends, remain. (5) The disparities in speed of the traffic stream may be positively related to crash probability, especially on Interstate highways. However, the data are not very consistent, and more data are needed. (6) On urban streets there appears to be a strong relationship between crash rates and the absolute speed of crash-involved vehicles. (7) The data demonstrating the relevance of speed dispersion in the traffic stream and speed deviations of crash-involved vehicles are based on correlational effects and therefore cannot be used to indicate that if slow-moving drivers were to increase their speed, their crash probability would be reduced. (8) There are unequivocal data to indicate that the risk of injuries and fatalities increases as a function of precrash speed or Delta-V. This is true for all road types. (9) The overall cost of speed-related crashes is much greater than the relationship between speed and crash probability indicates. This is because high-speed crashes are associated with greater injury levels than are low-speed crashes.

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

00758007

HS-042 770

English

p. 221-276

1998

Transportation Research Board Special Report

030906502X

Figures (7) ; References; Tables (3)

Costs; Crash rates; Crash risk forecasting; Crashes; Design speed; Fatalities; Hazards; High speed ground transportation; High speed vehicles; Injuries; Interchange ramps; Precrash phase; Risk assessment; Speed; Speeding; Traffic crashes; Traffic speed; Turning traffic

Accident costs; Speed differential

Finance; Highways; Railroads; Safety and Human Factors; I80: Accident Studies

TRIS, TRB

Dec 22 1998 12:00AM

• EFFECT OF SPEED LIMITS ON SPEED DISTRIBUTIONS AND HIGHWAY SAFETY: A SURVEY OF THE LITERATURE. APPENDIX C OF TRB SPECIAL REPORT 254
• REVIEW OF AUTOMATED TECHNOLOGIES FOR SPEED MANAGEMENT AND ENFORCEMENT. APPENDIX D OF TRB SPECIAL REPORT 254