The Discrete-Time Sequencing Expansion Problem

We consider a sequencing expansion problem in which capacity can be added only at discrete points in time. Given is a forecast of demand in each period, and a set of expansion projects each with a given capacity and cost. The problem is to determine the sequence of expansions necessary to provide sufficient capacity to meet the demand in all periods at minimum cost. The problem is solved using Lagrangean relaxation. Computational results are given.