Discussion of “Trade-Offs between Initial and Maintenance Costs of Highways in Cross-Slopes” by Manoj K. Jha and Paul Schonfeld

Abstract

Jha and Schonfeld’s paper addresses a critical “missing link” between infrastructure management systems and initial design/ construction decisions for a project. Specifically, the authors present a method to optimize highway alignment using trade-offs between initial and maintenance costs, focusing on overall lifecycle cost. They cite statistics to show that maintenance costs are significant over the life cycle of a project and argue that managers and engineers should make more extensive use of life-cycle cost analysis in the initial stages of a project. Their work highlights the difficulty in defining and quantifying maintenance costs for geotechnical infrastructure. We wholeheartedly agree with the authors that making truly effective decisions during design requires consideration of longterm costs, including maintenance costs. In this context, the authors have made a significant contribution by developing an optimization scheme to minimize life-cycle costs for transportation earthworks. We hope that their article will stimulate continued work on this important problem. In addition, we would like to raise several issues regarding the model and the problem in general to contribute to the discussion. First, the authors never define the activities they are including as “maintenance costs.” Terms such as “maintenance,” “repair,” and “rehabilitation” are used loosely in much of the infrastructure management literature. The lack of standard definition of the terms, in addition to the difficulty in tracking many of the costs that could be included, contributes to the difficulty in estimating life-cycle costs and creates confusion in the ongoing dialogue. We believe the paper will be more valuable as an archival record if the authors define the terms as used in their work. We concur that there is a severe lack of data available on these costs with regard to highway embankments and slopes, and we applaud the authors for developing a model for use in estimating these costs. Unfortunately, since it is difficult at present to evaluate the accuracy of the model, we simultaneously hope that transportation agencies will begin to collect and analyze such data so that the model proposed by the authors can be more rigorously evaluated and improved based on real data.