Estimation of Planning-Level Asset Preservation Costs: Case Study Involving Flexible Pavement Treatments
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Estimates of asset preservation costs at the planning level are vital inputs for project selection and programming, prioritization, budgeting, and contract administration. Over the years, however, there exists a paucity of analytical research on asset preservation costing, particularly with respect to the variation of project cost with respect to attributes such as project size and asset condition at the time of the project. Using data on flexible pavement preservation treatments at a state highway agency spanning years 2001 to 2006, this paper shows how project costs could be estimated more reliably at the planning stage and also investigates the functional relationships between project cost and attributes. Model functional forms that were explored include the Cobb-Douglas function and a variety of non-linear specifications. To avoid unduly restricting the models, flexible formulations were used to specify the response variable. Explanatory variables considered include functional class, location, year of treatment, treatment intensity, and asset condition prior to the treatment. The direction and strengths of scale economies and condition economies were duly investigated using mathematical forms that allowed for determining the partial derivatives of treatment cost with respect to relevant explanatory variables such as the asset dimensions and initial condition. The models are useful in assessing monetary preservation needs in long-term and in quantifying the monetary impacts of deferred preservation. Also, using appropriate Federal Highway Administration (FHWA) indices for temporal and spatial cost adjustment, the developed cost models could be transferred to other states for cost estimation of similar projects at the planning stage of preservation project development.