Optimizing concurrent execution of design activities with minimum redesign

Abstract

Overlapping is recognized as a common method in concurrent execution of design activities using early information to significantly shorten design completion time. Nevertheless, unplanned overlapping without thoroughly modeling the entire procedure may not necessarily reduce design duration but instead result in excessive redesign that can be very costly. Recognizing the necessity of finding an optimal overlapping strategy, this study proposes an integrated decision-making framework to optimize the schedule of the design activities using early information. Given the probabilistic nature of the design process, the overall design process has been modeled using discrete event simulation (DES) incorporating an overlapping concept to produce the expected duration and redesign efforts, which are aggregated as a criterion to evaluate the solution. Subsequently, the search for an optimal overlapping strategy is carried out using an overlapping strategy matrix (OSM) with a genetic algorithm (GA). The entire optimization procedure is implemented by integrating GA with DES in a synchronized manner. Effectiveness of the proposed approach has been discussed through an illustrative example and the results show that the proposed optimization method eliminates unnecessary redesign without significant delay or even with no delay in design completion time. © 2012 American Society of Civil Engineers.