Improving Data Accuracy of Roadway Departure Crashes: Practice in Virginia, USA, and Its National Implications

Despite the severity and frequency of roadway departure (RD) crashes, the definition and identification of these crashes has been inconsistent between agencies. As a result, significant differences exist in reported roadway departure crash deaths between many states, including Virginia, and the Federal Highway Administration (FHWA). This paper proposes a clear definition of roadway departure to eliminate confusion and to better analyze roadway departure crashes. A comprehensive literature review and in-depth survey questionnaire to state departments of transportation were used to clarify the differences among various terms. Using Virginia as an example, the cause of the discrepancy between Virginia and the FHWA on RD crash deaths was explored and a new method was proposed to more accurately identify RD crashes. The new definition defines a RD as a reportable crash on a non-intersection road section in which at least one vehicle involved leaves its intended travel lane and does one of the following: runs off the edge line (or edge if no edge line exists) of the road or crosses the centerline of an undivided road. Using the new method, the discrepancy between FHWA and Virginia RD fatality numbers was reduced from 24% to less than one half of one percent.


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  • Accession Number: 01145114
  • Record Type: Publication
  • Files: TRIS, ATRI
  • Created Date: Nov 29 2009 5:39PM