Performance of Guardrail Systems Encased in Pavement Mow Strips

Pavement mow strips are being used to combat growth of vegetation around guardrail posts. However, the effect of pavement post encasement on crashworthiness of strong post guardrail systems has not been investigated. In this paper, performance of these systems is examined using experimental testing and numerical simulation. Mow strip dimensions, materials, and depths are considered in addition to the presence “leave-out” sections around posts. Seventeen configurations using wood and steel posts embedded in various mow strip configurations and confinement conditions were subjected to dynamic impact testing with a bogie vehicle. Dynamic impact tests were numerically simulated and full-scale mow strip system models were assembled using the subcomponent models. A concrete mow strip with grout leave-outs was designed based on predictive numerical simulations. This design was subsequently constructed and subjected to full-scale crash testing. With reference to nationally accepted criteria, crash tests of a strong post steel guardrail system and a wood post guardrail system encased in the selected mow strip configuration were considered to be successful. Recommendations for implementation are provided.