Simulation Analysis of a Contract Modification Process Based on Stochastic Petri Nets: A Case Study of Mechanical and Electrical Installation Projects in the Guangzhou Metro

On account of many unpredictable factors, modification of contract during project construction is almost inevitable. At present, the contract modification management is inefficiency, leading to high change frequency and high cost. In this paper, a simulation model of stochastic petri nets systems is built to analyze the contract modification process of construction project, current process of mechanical and electrical installation contract modification in Guangzhou metro is taken as a case study. According to quantitative analysis and simulation results, this paper finds that the bottleneck problems of modification process lay in these three areas: modification files writing by construction organization, supervising engineer’s review, and sponsoring department’s review. Taking the average process efficiency into consideration, the authors suggest that optimized objects and factors focus on sponsoring department who should improve the efficiency of approval process in change review meetings and timely adjustments for changes in cost, to improve management lever of metro construction.