Application of Precast Concrete Barrier Adjacent to Steep Roadside Slope

When concrete barriers are installed adjacent to drop-offs or steep roadside slopes such as 1.5H:1V, a cast-in-place concrete moment slab is usually attached to the base of the barrier to resist lateral and overturning forces during vehicle impact. Cast-in-place construction can require more time on-site to build forms, pour the concrete, and allow for curing. This time constraint results in an increase in disruption to traffic and more exposure for construction workers. Furthermore, the installation of a moment slab is very costly and requires an additional construction phase to build the slab. Because the slab is normally under the shoulder and possibly the lanes, the disruption of traffic flow is increased. A new application of a precast 42-in.-tall single-slope concrete barrier for use in front of steep slopes was developed that does not require a moment slab. The lateral movement of the barrier is restricted by embedding it in soil. This design also reduces the embankment behind the barrier to 2 ft. The embedded barrier application was successfully evaluated under Manual for Assessing Safety Hardware Test Level 3 criteria. The permanent deflection of the barrier was 5.5 in. The use of the embedded concrete barrier in lieu of the typically installed barrier with a moment slab is expected to result in cost savings of approximately $300 per linear foot and reduced time to construct.