Steel Railing, Type IL-OH

Résumé du livre

Over the past few years, the Midwest Roadside Safety Facility worked with the Illinois and Ohio Departments of Transportation to develop a new side-mounted, steel tube bridge rail to satisfy the American Association of State Highway and Transportation Officials (AASHTO) Manual for Assessing Safety Hardware, Second Edition (MASH) Test Level 4 (TL-4) safety performance criteria. The new bridge rail was designed to be adaptable to multiple bridge deck configurations, including cast-in-place concrete slabs and prestressed box-beam decks. The system was designed to remain crashworthy after the placement of a future roadway overlay up to 3 in. thick. The final design incorporated three HSS tube rails supported by W6x15 posts spaced at 8 ft on-center. Additionally, a transition from the Midwest Guardrail System (MGS) to the new side-mounted, steel tube bridge rail was developed to satisfy MASH TL-3 criteria. The approach guardrail transition (AGT) incorporated the MGS upstream stiffness transition and 34-in. tall nested thrie-beam to account for future overlays. A distance of 9 ft was established between the last AGT post and the first bridge rail post in order to span over any structures that may prohibit post installation (abutments, wing walls and/or drainage features) Specialized HSS end rails were developed to extend between the adjacent bridge and AGT posts and provide the strength required to redirect errant vehicles. The development and full-scale testing of both the bridge rail and the transition were documented in previous reports. This report, the fourth in the series, summarizes the development and evaluation of the systems, contains CAD details and component variation descriptions, and provides implementation guidance for the Steel Railing Type IL-OH and its associated transition.