The great and multitudinous risks are confronted in the bridge construction

especially in the construction of cross-bay bridge

so more and more attention is paid to the risk management of the huge bridge project in the field of construction.According to the randomicity of the constructing procedure caused by a variety of risks in the construction of huge bridge

the thesis poses the adoption of the method of network program PERT which is possessed of the certainty of logic relationship and the uncertainty of movement duration to estimate the risks in the construction progress.Such method assumes that the uncertainty of the procedure duration has the characteristic of β distributing and transfers it into the certain network program to estimate constructing risk via counting its mathematic expectancy in terms of the influence between roads.The thesis states the application of PERT to estimate the risk in the construction process by a case study of one huge bridge along the Yong-Tai-Weng Expressway.It is expected to provide some references to this project as well as the similar project.