Many factors are involved in the design of drainage systems. Although not necessarily overriding, the cost is often one of the most important factors. This cost should be the total, overall cost of the alternative over its projected life, or life-cycle cost. Unless the life-cycle cost is considered over first cost, the owner cannot be assured of receiving maximum value for his construction and maintenance dollars. The importance of the other decision factors are established for army projects by the minimum functional requirements of the project. Except for determining a service life for the various types (materials) of drainage structures, the procedures for life-cycle cost analysis of such studies are well established. The procedures for economic analysis described in U.S. Army technical manual tm 5-802-1 can be used to determine life-cycle cost. U.S. Army regulation"economic analysis and program evaluation for resource management" gives the basic criteria and standards for economic studies by and for the department of the army. Provided in this paper is the supplemental explanation required to perform life-cycle cost analyses of drainage structures to determine the relative economic rating of design alternatives. The alternatives can then be order ranked by life-cycle cost, and the best design can be rationally and confidently selected.
Abstract