Guardrail Utilization: Cost-Effectiveness Computer Program to Analyze W-Beam Guardrail on Fill Slopes
TRP-03-004-79 (Guardrail Utilization)
Edward Post, Patrick McCoy, Richard Ruby, Patrick Chastain, Steven Rupp
The purpose of this study conducted by the University of Nebraska was to assist the Nebraska Department of Roads in establishing new guardrail design policies and standards in Nebraska which will take into consideration the relative "effectiveness" and "benefit" of guardrail and alternatives to guardrail installations as a function of highway type, traffic volumes, and guardrail installations as a function of highway type, traffic volumes, and the annualized costs of construction, maintenance, and repair. Effectiveness is a measure of the annual reduction in the number of injury accidents, whereas, benefit is a measure of the annual reduction in accident costs. This report describes the computer program developed to expedite the lengthy and tedious cost-effectiveness and benefit-cost calculations for making W-beam guardrail improvements on roadside embankments. Case study problems are worked to illustrate the usage of the hazard inventory and improvement alternative input data coding forms and the interpretation of the output listing. Also, the cost-effectiveness and benefit-cost methodologies, on which the program was developed, are discussed in detail. The hazard inventory and improvement alternative coding forms developed in this study are general in scope and include most roadside hazards that are likely to be encountered by an errant automobile. Recommendations for future additions to the computer program to include hazards other than W-beam guardrail and embankments are presented. The work accomplished in this study has demonstrated that the cost-effectiveness and benefit-cost computer program shows great potential in providing highway engineers and administrators in Nebraska with a rapid and efficient managerial tool for evaluating spot safety improvement projects and/or design projects in order to realize the greatest return on the capital investment made to reduce injury accidents.
Guardrail, Roadside Safety