Abstract

An object-oriented model is presented for optimized scheduling of repetitive construction projects such as: high-rise buildings, housing projects, highways, pipeline networks, bridges and tunnels. The model provides a number of practical features, and incorporates newly developed algorithms for scheduling of repetitive construction projects including: (1) a resource-driven scheduling algorithm for repetitive activities; (2) an interruption algorithm; and (3) an optimization procedure. The scheduling algorithm identifies the scheduled start and finish times as well as the assigned crew for each unit of a repetitive activity. The algorithm provides a schedule that complies with precedence relationships, crew availability and crew work continuity constraints, and considers the impact of a number of practical factors commonly encountered during scheduling. The interruption algorithm generates feasible interruption vectors for each repetitive activity in the project and provides added advantage over available formulations that consider arbitrary user-specified interruption vectors. The optimization procedure is based on a dynamic programming formulation. Unlike available dynamic programming formulations, the present formulation is capable of incorporating cost in the optimization process, thus offering valuable support to project team members in minimizing the overall cost of the project. For each repetitive activity in the project, the present model assists the planner in selecting the optimum crew formation and interruption vector from a set of possible alternatives. As such, the model can be used to evaluate the impact of different project acceleration strategies (i.e. multiple crews, increased crew size, overtime policies, or additional shifts) on the overall cost. The present model is implemented as a prototype software system. The system is developed as a 32-bit windows application that supports user-friendly interface including menus, dialog boxes, and windows. A number of application examples are analyzed to illustrate the use of the model and demonstrate its capabilities. The model can be used as a decision support system for generating optimized schedules for repetitive construction projects. This should contribute to cost-effective delivery of constructed projects.