Investigation and Development of a MASH Test Level 6, Cost-Effective, Barrier System for Containing Heavy Tractor Tank-Trailer Vehicles and Mitigating Catastrophic Crash Event - Phase V

Run-off-road (ROR) crashes involving truck-tank trailer combination vehicles can be disastrous and create significant and lasting economic harm. Gasoline tank-trailer crashes have resulted in catastrophic fires, leading to bridge and overpass collapses, pavement damage, extensive road closures and repairs, and most importantly loss of life. However, historically the only approved roadside barrier system capable of containing and redirecting a truck-tank trailer vehicle to the national crashworthiness standards of NCHRP Report No. 350 or MASH was over 90 in. tall, extremely expensive, and limited application and sight distance for drivers. As a result, this barrier system has been installed in only a few locations since it was tested in the 1980s. A new barrier system was constructed and tested under the MATC Year 4 project which is significantly lighter, less expensive, shorter, and comparable to existing barriers meant to capture truck-van body trailer combination vehicles to MASH impact criteria. It is anticipated that the new MATC barrier evaluated in this study will be more cost-competitive with existing high-capacity barrier systems and will be installed in many more locations than the predecessor barrier system. Still, extensive implementation concerns exist. This project aims to resolve as many of the implementation-related aspects which state DOTs must address to add a new, high-capacity, MASH-TL-6 compliant barrier into standard designs and specifications, including transitions, median and roadside applications, and requirements for connections to foundations or bridge decks.

The research objective of this project is to facilitate the implementation of the new, lower-height, optimized TL-6 barrier for state DOTs by performing a survey of state DOT design and implementation needs and performing critical barrier design details and providing guidance for addressing those needs. The prioritization provided by the state DOT survey will inform the design steps, which are anticipated to include but are not limited to: foundation design for stiff soils and subgrades; determination of barrier length-of-need (LON) based on ZOI and typical contact lengths; accommodations for curves; adaptation for roadside applications (non-median); drainage considerations; and minimum strengths of bridge decks to facilitate barrier loads. Implementation recommendations will be discussed in a technical summary report and shared with state DOT representatives in roadside safety community meetings.

Current designs for MASH TL-6 compliant roadside barriers are extremely heavy, cumbersome, and difficult to construct. The new barrier system tested during MATC TL-6 Year 4 will increase the cost-effectiveness of installing barriers in high-risk locations to shield critical infrastructure including schools and government buildings from gasoline tank-truck trailer impacts, including at or near bridges. The implementation guidance performed in this research will greatly accelerate the adoption and acceptance of this barrier system into state DOT standard plans and ensure rapid acceptance and implementation of this system in state DOT bid letting.

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