PERT Schedule Development And Tradeoffs Under Resources Constraint

Within the Project Time Management, schedule development and time-resources tradeoffs are two major points. Regards of long periods, huge investment, numbers of influencing factors and uncertainty of magnificent constructions, PERT seems to have good effects as one of the schedule development techniques, and is highlighted by project managers.However, there exists something that should be considered related to the adopted schedule development methods and resources tradeoffs techniques at present. Particularly, Activity Duration Estimates are inaccuracy, Activity's ES, that is, Network Node's TE calculation is not guaranteed by traditional PERT, Risk Quantification is not fully considered when implementing resources tradeoffs. Therefore, this paper firstly puts forward to modify the average duration and its variance based on combining the experts' objective data and subjective realization of Activity Duration Estimates. Secondly, it advances to use probability theory and Monte Carlo Simulation (MCS) to produce Activity Duration Random, and solve the problem that how to make schedule development, especially calculating the Node's TE and Planned Project Duration based on given schedule risk probability. Besides, this paper analyzes time-resources tradeoffs of PERT resource-constrained scheduling with use of ACI and CRI as risk indexes dealing with schedule development, then adopting 0-1 integer programming algorithm, a resources reallocation model and a calculating method which aims at solving the time-resources tradeoffs problem of PERT resource-constrained scheduling are established. Finally, an application program with the function of schedule development is developed using Delphi 7.0 and is applied to a project example. The results indicate that the established model above based on schedule risk factors is reasonable to handle scheduling and resources reallocation.The result of this paper offers to project managers some beneficial information, such as each activity's ACI and CRI, Planned Project Duration under different resource constraint and so on. With the information above, managers are able to make decision scientifically and wisely. Besides, engineers can process time management more flexible and maximize the effect of construction project with use of the modified PERT schedule.