In areas where vehicle collisions are common, standard metal roadside barriers (MBGRs) are very expensive to maintain. Additionally, communities and agencies are increasingly asking Caltrans to install aesthetically pleasing roadside barriers on highways that cannot be installed with standard corrugated beam barriers. Some highway construction projects have actually been delayed due to the unsightly appearance of the barriers. Most aesthetically pleasing barriers are proprietary and are expensive to build and maintain. Caltrans is developing aesthetically pleasing low-maintenance barriers (ALMGRs) that are virtually maintenance-free and aesthetically pleasing to the eye.
       The objective of this study was to design and test a new guardrail system that meets the American Association of State Highway and Transportation Officials (AASHTO) Guide to Assessing Safety Equipment (MASH) Level 3 (TL-3) full-scale crash test recommendations. The guardrail system would meet California requirements for aesthetic guardrails and would be able to withstand vehicle impacts with little or no damage. It would have a relatively low life cycle cost, contain a minimum number of parts for service station inventory, and be easy to repair or replace when necessary. The study was divided into three phases. Phase one was to design and test a concrete base that could be used as a guardrail system in conjunction with an aesthetically pleasing bridge barrier. Phase two would design and develop new guardrail systems that meet the California needs described above. Phase three would fabricate and test the new guardrail systems developed in Phase two.
       On October 16, 2013, the Road Safety Research Group (RSRG) tested the MASH 3-11 on an ST-10 bridge barrier installed on a 30-inch (762 mm) deep by 20-inch (508 mm) wide concrete foundation. To simulate a worst-case installation scenario, the barrier was installed in soft soil with a 3 to 1 slope excavated behind the barrier. The slope should begin 3 feet (914 mm) from the back edge of the barrier’s concrete base and should be equal to the depth of the base. The foundation was poured in two stages; the first pour was for the foundation and the second pour was for a 6-inch (152 mm) high curb. These two pours create a cold construction joint between the foundation and the curb. The vehicle, a 2006 Dodge Ram 1500 four-door pickup truck, struck the barrier at 62.0 mph (99.8 km/h) at an angle of 24.7 degrees. The ST-10 bridge barrier and trench foundation combination changed the direction of travel of the test vehicle with minimal movement toward the foundation. However, upon losing contact with the barrier, the vehicle rolled over. Although this combination did not meet the MASH evaluation criteria (F criteria), the trench foundation performed as intended. Therefore, this type of trench foundation is recommended for any bridge barrier design meeting NCHRP Report 350 or MASH Test Level 3 or 4 standards. These barrier/foundation combinations may be considered for use as TL-3 barriers on California roadways.