01366078

Component

Roadside designers have used the Severity Index (SI) approach to model roadside hazard severity for some time. SI is a linear function of speed and the slope values for the SI curves were based primarily on engineering judgment. While this approach to determining crash severity has been widely used, it has never been validated or compared to real-world crash data because there were no crash databases available with reconstructed impact speeds that could be used to check the validity of the SI-speed relationship. This paper reviews the traditional SI approach results compared to collected crash data from the National Cooperative Highway Research Program (NCHRP) 17-22 crash database and presents a new approach for estimating crash severity proposed for use in the updated version of Roadside Safety Analysis Program (RSAP). The Effective Fatal Crash Cost Ratio (EFCCR) is proposed to replace the SI in the updated version of RSAP. The EFCCR uses the severity distribution of reported crashes for any hazard, adjusted for unreported crashes, then divides the average crash cost calculated for any particular year by the cost of a fatal crash in that same year creating a dimensionless measure of risk. This dimensionless value allows for direct comparison of hazard severity between roadside hazards.

This paper was sponsored by TRB committee AFB20 Roadside Safety Design

01362476

12-2684

English

17p

2012

Transportation Research Board 91st Annual Meeting

Digital/other

Figures; References; Tables

Costs; Crash data; Crashes; Geometric design; Highway safety; Ratios; Roadside hazards

Design; Highways; Safety and Human Factors; I20: Design and Planning of Transport Infrastructure; I82: Accidents and Transport Infrastructure

Transportation Research Board Annual Meeting 2012 Paper #12-2684

TRIS, TRB

Feb 8 2012 5:11PM