THE DISCRETE TIME-COST TRADEOFF PROBLEM REVISITED

In the management of a project, the project duration can often be comp ressed by accelerating some of its activities at an additional expense . This is the so-called time-cost tradeoff problem which has been stud ied extensively in the project management literature. However, the dis crete version of the problem, encountered frequently in practice and a lso useful in modeling general time-cost relationships, has received o nly scant and sporadic attention. Prompted by the present emphasis on time-based competition and recent developments concerning problem comp lexity and solution, we reexamine this important problem in this paper . We begin by formally describing the problem and discussing the diffi culties associated with its solution. We then provide an overview of t he past solution approaches, identify their shortcomings, and present a new solution approach. Next, we present network decomposition/reduct ion as a convenient basis for solving the problem and analyzing its di fficulty. Finally, we point to several new directions for future resea rch, where we highlight the need for developing and evaluating effecti ve procedures for solving the general time-cost tradeoff problem. To t he best of our knowledge, the popular project management software pack ages do not include provisions for time-cost tradeoff analyses. Our wo rk, we hope, will provide the groundwork and an incentive for alleviat ing this deficiency.