Book Description

A new steel, side-mounted, beam-and-post, bridge rail was designed, crash-tested, and evaluated according to safety performance guidelines included in the American Association of State Highway and Transportation Officials Manual for Assessing Safety Hardware (MASH) for Test Level 4 (TL-4). The new bridge rail system was designed to be compatible to multiple concrete bridge decks utilized by the States of Illinois and Ohio. Bridge rail configurations were designed and optimized based on weight per foot, constructability, and safety. Post-to-rail and rail-to-rail connections were designed for the new bridge rail. Several concepts for these connections were configured, and after discussion with representatives from the Illinois and Ohio DOTs, a preferred concept was selected for full-scale crash testing with a single-unit truck, a pickup truck, and a small car. The new bridge rail consisted of three tubular steel rail elements supported by W6x15 (W150x22.5) steel posts mounted to the exterior, vertical edge of the concrete deck and spaced on 8 ft (2.4 m) on centers. The top rail element was an HSS 12-in. x 4-in. x 1⁄4-in. (HSS 304.8-mm x 101.6-mm x 6.4-mm) and the lower two rail elements were HSS 8-in. x 6-in. x 1⁄4-in. (HSS 203.2-mm x 152.4-mm x 6.4-mm). The centerline heights of the rail elements were 37 in. (940 mm), 28 in. (711 mm), and 16 in. (406 mm) above the surface of the deck for the top, middle, and bottom rails, respectively. Three MASH TL-4 crash tests were performed on the new bridge rail, which successfully contained and redirected the MASH TL-4 vehicles. All occupant risk measures and evaluation criteria were within MASH limits. For MASH test designation no. 4-12 with the single-unit truck, the impact severity did not meet the minimum limit of 142.0 kip-ft (180.6 kJ). Thus, test designation no. 4-12 is recommended to be re-run. However, a maximum roll angle of 36 degrees and a dynamic deflection of 4.3 in. (109.2 mm) represent a positive indication that a subsequent test with a single-unit truck would likely meet MASH TL-4 impact safety criteria.