Use of Energy Absorbing Breakaway Posts for W-Beam Guardrail in Frozen Soil Conditions

The goal of this project was to develop, test, and demonstrate the application of breakaway posts with energy absorbing capability to enhance the safety performance of W-beam guardrail in frozen soil conditions. From the four initial concepts, two designs were selected for further evaluation based on potential impact performance, manufacturability, and cost. The bent-plate design showed the desired failure mechanism though the force level was lower than that required for proper impact performance. The bogie test was then simulated using the LS-DYNA computer simulation program. Based on the calibrated simulation model, the thickness of the bent plate was optimized to increase the force level while maintaining the manufacturability. Additional bogie tests were conducted on the optimized design, and the results showed acceptable force levels. Computer simulation of a guardrail system with breakaway posts was then conducted with satisfactory results indicating that implementation of this new guardrail post could potentially reduce the severity of guardrail crashes and the associated serious and fatal injuries. The next step was to conduct a full-scale crash test at the Midwest Roadside Safety Facility. The post manufacturer had agreed on the finalized design and to contribute to the cost for the full-scale crash test. However, after reevaluating the potential market for the new posts, the manufacturer determined them to be not viable in the current market and withdrew support from the full-scale crash test. Implementation of the new posts requires fabrication and full-scale crash testing followed by field tests in collaboration with State Departments of Transportation.