Development of a MASH Test Level 4 Open Concrete Bridge Rail

An open concrete bridge rail was designed and developed according to safety performance guidelines in the American Association of State Highway Transportation Officials (AASHTO) Manual for Assessing Safety Hardware (MASH) for Test Level 4 (TL-4). Systems designed and developed under previous guidance were studied, and their geometric information and full-scale crash testing performance was studied to establish the geometry of the new bridge rail. Yield-Line Theory and the AASHTO Post and Beam design methods were studied, and a modified version of the AASHTO Post and Beam method was utilized to determine the capacity of the new open concrete bridge rail. Both 36 and 39-in. (914 and 991-mm) tall variants of the new open concrete bridge rail were configured. Both variants incorporated a 27-in. (686-mm) tall by 14-in. (356-mm) wide rail, supported by 36-in. (914-mm) long x 10 in. (254-mm) wide posts in the interior region, and 72-in. (1,829-mm) long posts in the end region. Posts in both regions were separated by a 72-in. (1,829-mm) long gap. Posts in the 36 in. (914 mm) tall variant were 9 in. (229 mm) tall, and posts in the 39-in. (991-mm) tall variant were 12 in. (305 mm) tall. Three bridge deck reinforcement configurations were developed to provide different options of reinforcement patterns that were compatible with the new bridge rail. Three concrete end buttress configurations, each with three different approach guardrail transition (AGT) options, were proposed to provide examples of how to properly transition from guardrails installed off the bridge to the open concrete bridge rail. Three full-scale crash tests were recommended to be conducted under MASH test designation nos. 4-10 through 4-12, with 2,425 lb (1,100 kg), 5,000 lb (2,270 kg), and 22,000 lb (10,000 kg) vehicles to evaluate the safety performance of the open concrete bridge rail. Advisor: Jennifer D. Rasmusse