Unit Price Estimating of Roads Maintenance Activities using Exponential Robust Regression

Abstract

Good road maintenance schemes allow reducing costs and extending the serviceability life of roads. There are several methods to plan these project maintenances, but all of them require input information about maintenance costs. These costs can be very different depending on the geographical zone and the contracted volume (economies of scale). In this paper, a structured methodology for estimating road maintenance activities unit price is proposed, modeling the exponential decay nature of economies of scale. Using an exponential robust regression procedure, curves are adjusted, and parameters generated. Additionally, a cost contingency analysis is performed in order to provide cost ranges associated to specific contracted volumes. The validation of the methodology was carried out through its application in estimating unit prices of real road maintenance projects in Chile. The procedure may be used by road planners as well as by contractors looking for a more confident approach before participating in a bid. Furthermore, this methodology is not limited to road maintenance, but also to any other field where economies of scale and exponential fitting are needed.