Midwest Guardrail System (MGS) with an Omitted Post

The objective of this research study was to evaluate the MGS (31” tall W-beam guardrail) with an omitted post according to the safety performance criteria provided in MASH. A single full-scale crash test was conducted with the 2270P pickup truck in accordance with MASH test no. 3-11. The small car test, test no. 3-10, was deemed unnecessary as the pickup truck test would result in higher rail loads, a greater propensity for rail rupture, and a greater risk of failure. The test installation utilized standard 6-ft (1.8-m) long steel guardrail posts with 12-in. (305-mm) deep blockouts. A single post was omitted near the center of the 175-ft (53.3-m) long installation. Test no. MGSMP-1 resulted in the guardrail capturing and smoothly redirecting the 2270P vehicle. The vehicle remained upright, and all vehicle decelerations were within the recommended occupant risk limits. As such, the MGS with an omitted post satisfied the TL-3 safety performance criteria found in MASH. Following the full-scale crash testing, implementation guidance and recommendations were provided regarding the omission of a post within various MGS configurations, including MGS adjacent to 2:1 fill slopes, MGS on 8:1 approach slopes, MGS in combination with curbs, wood post MGS, non-blocked MGS, terminals and anchorages, MGS stiffness transition to thrie beam approach guardrail transitions, and MGS long-span systems