Improved method for roadside barrier length of need modeling using real-world trajectories

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 55 mph 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 10 m from the roadway. For hazards closer than 10 m, 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.