3D Modeling of Highway Guardrails for Sight Distance Assessment

Safety barriers limit the severe consequences to occupants of vehicles leaving the roadway from colliding with obstacles, yet they may significantly reduce the available sight distance (ASD). A procedure was devised to accurately recreate highway guardrails in three dimensions (3D), fitting the barriers onto the curve roadsides. The effect of these devices on the reduction of the ASD was thus evaluated in a set of case studies comprising different curve radii overlapped with different vertical alignments and combined each with two safety barriers in two-lane rural roads. The 3D models of highway curves with the selected guardrails were created in a geographic information system. Then, a geoprocessing model was used to compute the ASD. The results made it possible to quantify the ASD reduction produced by the barrier with a higher containment level in relation to the highway design parameters, which can assist authorities in developing more comprehensive safety device standards.