Highlights Improved procedure for computing roadside barrier length-of-need recommendations. Roadside barrier length of need for any desired level of protection. 2011 Roadside Design Guide length-of-need is more conservative closer to the roadway.
Abstract The 2011 AASHTO Roadside Design Guide (RDG) contains perhaps the most widely used procedure for choosing an appropriate length of need (LON) for roadside barriers. However, this procedure has several limitations. The procedure uses a highly simplified model of vehicle departure, and the procedure does not allow designers to specify an explicit level of protection. A new procedure for choosing LON that addresses these limitations is presented in this paper. This new procedure is based on recent, real-world road departure trajectories and uses this departure data in a more realistic way. The new procedure also allows LON to be specified for a precisely known level of protection – a level which can be based on number of crashes, injury outcomes or even estimated crash cost – while still remaining straightforward and quick to use like the 2011 RDG procedure. In this analysis, the improved procedure was used to explore the effects of the RDG procedure’s assumptions. LON recommendations given by the 2011 RDG procedure were compared with recommendations given by this improved procedure. For 55mph roads, the 2011 RDG procedure appears to lead to a LON sufficient to intercept between 80% and 90% of right-side departures that would otherwise strike a hazard located 10m from the roadway. For hazards closer than 10m, the 2011 RDG procedure intercepts progressively higher percentages of real-world departures. This suggests the protection level provided by the 2011 RDG procedure varies with the hazard offset, becoming more conservative as the hazard moves closer to the roadway. The improved procedure, by comparison, gives a consistent protection level regardless of hazard location.
Improved method for roadside barrier length of need modeling using real-world trajectories
Accident Analysis and Prevention ; 80 ; 162-171
2015-03-13
10 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
Improved method for roadside barrier length of need modeling using real-world trajectories
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