Resource constrainted pro-reactive project scheduling based on dynamic update of activity duration information
In reality projects are carried out in an uncertain environment due to the influence of various external uncontrollable events.Accordingly,a robust baseline schedule is supposed to be constructed based on the estimated variability in the proactive phase aiming at absorb-ing as much execution uncertainty as possible by incorporating some time buffer.Nevertheless,unexpected disturbances may still occur to cause deviations during project execution when dis-ruptions cannot be absorbed by the proactive baseline schedule.In this case,reactive procedures are instrumental to restore the schedule feasibility.Notably,the information about activity du-rations will update dynamically during the progress,in other words,the variability of activity duration decreases gradually with the increase of available information.This paper investigates the proactive-reactive project scheduling integration optimization based on the decreasing vari-ability of activity duration.Specifically,the proactive scheduling sub-problem aims to construct a stable baseline schedule by formulating an optimization model with the minimization of the expected total cost.Afterwards a tabu search heuristic is developed with the consideration of NP-hard nature.Due to the dynamic update of the activity duration information,the reactive scheduling sub-problem aims to dynamically balance the resource occupation cost and the activ-ity deviation cost by determining the reasonable adjustment time points.The goal in this study is to minimize the actual total cost of the project by means of the integration of proactive and reactive scheduling.The following conclusions are drawn from computational experiments.First,the algorithm for solving the proactive scheduling sub-problem can receive high-quality solutions so that the baseline schedules can be used as the best guide for actual implementation.Secondly,different reactive strategies show their own advantages in different scenarios,generally,hybrid strategies provide better results than others.Hence,the integration of proactive and reactive scheduling can provide guidance for managers to control the cost of the whole project process.
project schedulingoptimization modeltabu searchpro-reactivedynamic activity duration information
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