The effects of embedment depth, soil properties, and post type on the performance of highway guardrail post

The objective of this research study was to determine if the current guardrail design could be modified to achieve the necessary strength when full post embedment could not be achieved. The purpose of this report was to assess the effects of post type, soil conditions, and embedment depth on the load-deformation characteristics of the guardrail post. With this information, it is believed that a successful guardrail can be designed using more post with less than a full 38 in. embedment. Posts with only 18 in. or 24 in. embedment could be used at the 3 ft-1 1/2 in. spacing and still produce the required strength, for example. A series of static load tests were conducted on timber and steel posts embedded 18 in., 24 in., 30 in., and 38 in. in two different soils to determine the effects of post type, soil conditions, and embedment depth on the amount of energy dissipated by the soil. The results of these field tests were used to verify a mathematical model which could be used to predict guardrail post load capacity.