Relative Importance of User and Agency Costs in Pavement LCCA

Pavement condition affects the cost of the road users and the cost of highway agencies. User costs include two components, namely vehicle operating costs (e.g., fuel, repair/maintenance and so on, which depend on pavement roughness) and non-vehicle operating costs (e.g., pavement rehabilitation related delays, which depend on lane closure practices). Agency costs depend on pavement condition (i.e., surface distress and structural capacity), which define the feasible set of rehabilitation alternatives amongst those available for a particular pavement type. As recommended by federal directives, life cycle cost analysis of pavements should include both these streams of costs. However, the majority of state highway agencies consider only their own costs in pavement life cycle cost analysis. Those that consider user costs are typically dealing with pavement rehabilitation delay costs only. The paper at hand demonstrates the importance of considering all streams of costs in pavement life cycle cost analysis by comparing the relative magnitudes of vehicle operating costs, non-vehicle operating costs and agency costs. The analysis was conducted using the computer program PID (Pavement Investment Decisions), developed under National Cooperative Highway Research Program (NCHRP) Study 1-33. The analysis covers a variety of traffic and pavement conditions. Agency costs were estimated for a selected number of alternative pavement treatments using unit costs obtained from Washington State Department of Transportation (WSDOT). Two sets of user cost relationships were used for quantifying user costs. The results are presented in the form of the percentage of each stream of costs and clearly demonstrate that user costs can be very significant higher than agency costs and hence, should not be overlooked in pavement life-cycle cost analysis.