System simulation has proved to be an effective tool for planning and improving the performance of a construction process in many successful case studies. However, with the aid of a three-dimensional s3Dd visualization system, simulation technology will be engaged to its farthest-reaching potential. This paper presents a geographic information system (GIS)-based visual simulation method, in which system simulation techniques are integrated with visualization techniques. The GIS-based visual simulation system (GVSS) was developed by the authors. The GVSS is a simulation tool offering powerful planning, visualizing, and querying capabilities that facilitate the detection of logic errors in simulation models. The software also helps to understand the comprehensively complex modeled construction process, and is capable of organizing vast amounts of spatial and nonspatial data involved in simulation. A hydroelectric project, which will take place on the Yellow River in the northwest of China, is used as an example. An optimum equipment set scheme is determined by simulating a variety of scenarios taking place under different construction conditions. Likewise, other parameters, such as the construction sequence of dam blocks, the monthly intensity of the concrete process, and the construction appearance at the middle and end of each year, are obtained. Meanwhile, the complex processes of dam construction are demonstrated dynamically using 3D animation, which provides a powerful tool for quickly and comprehensively understanding the whole construction process. The GVSS has proven to be a helpful and useful tool for the design and management of concrete dams.

The path float use in the network is an effective method used to cope with various uncertainties existing within the construction. However, the current path float calculating method may bring misleading information to the managers on site and then cause project duration risk in the construction. The purpose of this paper is to present a new method, which calculates the noncritical path float in the program evaluation and review technique (PERT), to copy with the uncertainties within the network implementation, and to reduce the misleading information. An example network was analyzed with the new method, the results showed the consistent path float under required completion probability and required duration. The new path float concept will bring useful planning information to the managers and the planners in the construction.