Estimating Model Of Project Duration Based On Uncertainty And Dynamic Of Risks

During numerous risks of the project, the risk of duration is most important. The reason is that construction period’s delay will make effectiveness of the various project participants and then the benefits of the project will be decreased, especially for owner. If the project cannot be completed and put into operation before a limited completion time, the existence foundation of the project will be destroyed. The general negative impacts include the increasing of the project cost, the burden of the project loan interest and the project cash flow cannot be implemented as planned.The general project schedule is based on the critical path method (CPM), its basic assumption is the duration of each activity in network schedule is certain. Actually, due to the uncertainty factors, such as political, economic, meteorological, hydrological, construction environment, etc. The duration of the process activities in the construction of the project is random, thus arises how to calculate the time parameters of network schedule and time limit for a project can be implemented as planned. This paper makes a brief comparison between the classic PERT network plan and Monte Carlo simulation, then established the gray Markov network planning model and coupling dynamic risk Markov model on the basis of the two random uncertainty research methods:grey system theory and Markov decision,Firstly, this paper compares the classic PERT network plan and the Monte Carlo simulation results, through statistic the number of each process appeared on the critical path to produce thinking of the following questions:what is the measure of the key working procedure? How to define the critical path in stochastic network program model? Then, explains the reasons for these differences in the form of mathematical reasoning:ignore the influence of non-critical path.Secondly, by introducing grey number ordering rules to build a full range of network plan time parameter calculation rules, interval network planning model is presented in this paper. In order to reduce the interference of gray-scale amplification effect, revise the part beyond the reasonable range. Thirdly, this paper further explored with triangular whitenization weight function of network planning model based on the interval network planning model, its main purpose is to introduce a probability distribution to reflect the grey information more accurately.Lastly, the necessary exploring of time limit for a project to estimate under the majeure influence of earthquake and strike, getting the method for estimating the time limit for a project in accordance with dynamic decision-making.It is unable to build a whole theory system and framework about the stochastic planning model, some section of this paper still exist the possibility of improvement. At the end of the paper, it summarizes several research directions which are worth to being explored. It is expected that this paper can offer some ideas to future research.