The Crash Severity Impacts of Fixed Roadside Objects

This paper performs a comprehensive analysis of significant factors that affect crash severity involving fixed roadside objects, through improved statistical efficiency along with disaggregate and multivariate analysis. The in-service performance of roadside hardware on the entire urban state route system in Washington State is analyzed by developing multivariate statistical models of injury severity in fixed-object crashes using discrete outcome theory. The developed models are multivariate nested logit models of injury severity and they are estimated with statistical efficiency using the method of full information maximum likelihood. The results show that leading ends of guardrails and bridge rails, along with large wooden poles (e.g. trees and utility poles) increase the probability of fatal injury. The face of guardrails is associated with a reduction in the probability of evident injury, and concrete barriers are shown to be associated with a higher probability of lower severities. Other variables included driver characteristics, which showed expected results, validating the model. For example, driving over the speed limit and driving under the influence of alcohol increase the probability of fatal accidents, and drivers that do not use seat belts are associated with an increase in the probability of more severe injuries. These results highlight the importance of roadside design and provide insights into ways to decrease the severity of run-off-the-roadway crashes.

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  • Authors:
    • Holdridge, Jason M
    • Shankar, Venky N
    • Ulfarsson, Gudmundur F
  • Publication Date: 2005


  • English

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  • Accession Number: 01000787
  • Record Type: Publication
  • Files: TRIS, ATRI
  • Created Date: Jun 14 2005 3:59AM