Optimization of line of balance scheduling considering work interruption

Line of Balance (LOB) technique is frequently used for scheduling typical repetitive projects, in which crew work continuity is maintained and multiple crews per activity is allowed. Allowing work interruptions intentionally; however, might enhance project performance. The determination of optimum interruption values and the repetitive units at which work interruptions are permitted are challenging problems. Optimization problems have been traditionally solved by two approaches; heuristic methods and optimization techniques. Although heuristic methods can handle large-size projects, they do not guarantee optimal solutions. In this paper, a mathematical optimization model is developed to optimize project duration in LOB scheduling considering work interruption. Constant activity progress rate is assumed, work continuity is maintained, and planned work interruptions are allowed. Optimum interruption values and the activities' interrupted units are determined. Details of model formulation are illustrated by an example project. The developed model is then validated by a case study project and the principal conclusions are drawn. Although work continuity is an essential requirement in LOB scheduling, allowing for planned work interruption enhances project performance. The model can be used to study the project under various scenarios and the project manager can select the best alternative that meets his/her needs.