Final report.

NTL-OPERATIONS AND TRAFFIC CONTROLS-OPERATIONS AND TRAFFIC CONTROLS ; NTL-SAFETY AND SECURITY-Highway Safety ;

Determination of the maximum Midwest Guardrail System (MGS) mounting height was performed in two phases. Phase I concentrated on crash testing: two full-scale crash tests were performed on the MGS with top-rail mounting heights of 34 in. (864 mm) and 36 in. (914 mm), each impacted by 1100C vehicles. Both system heights satisfied the Manual for Assessing Safety Hardware (MASH) Test Level 3 (TL-3) evaluation criteria for test no. 3-10. Phase I was documented in the Midwest Roadside Safety Facility (MwRSF) Report No. TRP-03-255-12. Phase II, the subject of this report, concentrated on a detailed analysis of an increased-height MGS using computer simulation (Barrier VII and LS-DYNA). It was shown that on level terrain the MGS would satisfy MASH TL-3 evaluation criteria with rail heights up to 36 in. Also, errant passenger vehicles were successfully contained on approach slopes as steep as 6:1 when the rail was mounted at 36 in. Also, the 820C vehicle redirection was improved on 8:1 approach slopes with rail mounting heights as large as 36 in. (914 mm). Furthermore, the effects of various vehicle geometries and their associated complications were investigated. Additional full-scale vehicle crash tests are necessary to confirm the simulation results before these taller systems can be deemed crashworthy according to MASH. Nonetheless, there appeared to be a considerable amount of upside tolerance for the rail height on the MASH-approved MGS. Evidence of this was given in a prior high-flare-rate study and the current study.

US Transportation Collection