MSE Wall Behavior during Large Truck Impact at High Speed against Barrier on Top of Wall

Abstract

Some 45 years ago the total number of annual deaths on US roadways was slightly over 50,000. In 2020, this number has been reduced to less than 39,000 even while the number of kilometers traveled has almost doubled. One of the major contributing factors to this life-saving improvement is the development of better roadside safety barriers. This paper describes one of the largest instrumented crash tests with a 352 kN truck hitting a 1.07m high reinforced concrete barrier at 79.5 kph and a 15 degree angle. The barrier transferred the load to the Mechanically Stabilized Earth (MSE) wall through the sliding and rotation of the barrier-moment slab placed on top of the wall’s edge. The instrumentation indicated that some of the MSE wall strips in the vicinity of the crash area were brought to the pull-out failure load during the impact. However, since the impact duration was very short, the displacement of the front of the wall and the barrier were tolerable and the wall needed only cosmetic repair. The maximum horizontal dynamic force on the barrier at impact was 712 kN and the maximum lateral permanent displacement of the barrier was 31 mm. The truck was properly redirected onto the road while the wall experienced minimal damage. As such, the barrier and wall design was considered successful. Design guidelines are suggested for a barrier-MSE wall assembly to resist such a large truck impact.