This report documents and presents the results of a study to evaluate the impact performance of widely used roadside safety elements for a 1,500 lb vehicle and to identify potential modifications that would enable existing roadside safety elements to accommodate a design vehicle weighing as little as 1,250 lb. A full-scale crash test program coupled with an extensive computer analysis study were used to evaluate impact performance. Elements evaluated included the concrete safety shaped barrier (CSSB), the G4(1S) roadside barrier, breakaway luminaire and sign supports, a base-bending sign support, the eccentric-loader guardrail terminal, crash cushions, and roadside safety features including slopes, ditches, driveways, and curbs. It was concluded that: (a) modifications to the CSSB may be needed to mitigate overturn problems; (b) performance of the G4(1S) is satisfactory; (c) performance of most slip-base, breakaway supports is satisfactory but the frangible transformer base is not acceptable; (d) a single 4 lb/ft steel U-post sign support is marginally acceptable; (e) the eccentric-loader guardrail terminal is not acceptable but with modifications, it could possibly be made acceptable; (f) the sand-filled plastic drum crash cushion can be easily designed to accommodate a 1,300 lb vehicle; (g) although no apparent modifications are needed for slope, ditch, and driveway designs, more overturns can be expected with the small vehicle if these features are not constructed and maintained so as to avoid poorly compacted, eroded, and irregular terrain; and (h) to minimise small car overturn, AASHTO curb types C, E, and G, or similar designs are preferred. (Author/publisher)
Samenvatting