Development of Guardrail Runout Length Calculation Procedures

摘要

Guardrail runout length recommendations contained to AASHTO's Roadside Design Guide were reevaluated in order to determine optimal guardrail length of need. Encroachment data collected along Canadian highways was evaluated in a manner similar to that used with Huchinson and Kennedy encroachment data to reproduce procedures contained in AASHTO;s Roadside Design GUide. A benefit cost analysis of extending guardrails was also conducted as an alternative procedure for defining appropriate guard rail runout lengths. Both analysis procedures indicate that guardrail runout lengths recommended by the roadside design guide are excessive. Highway agencies are recommended to select on of the two new procedures for identifying appropriate guardrail runout lengths. Guardrail runout length recommendations contained in AASHTO's Roadside Design Guide were re-evaluated in order to determine optimal guardrail length of need. Encroadhment data collected along Canadian highways was evaluated in a manner similar to that used with Hutchinson and Kennedy encroachment data to reproduce procedures containted in AASHTO's Roadside Guide. A Benefit cost Analysis of extending guardrails was also conducted as an alternative procedure for defining appropriate guardrail runout lengths. Both analysis procedures indicate that guardrail runout lenghts recommended by the Roadside Design Guide are excessive. highway agencies are recommended to select one of the two new procedures for identifying appropriate guardrail runout lengths.