It has a well-deified objective stated in terms of scope, schedule and cost. 它在项目范围，进度计划及成本上都有明确的定义。
Selecting the shortest total duration of the construction unit scheduling is one of the key issues in bridge project planning. 选择总工期最短的施工段施工次序是桥梁工程施工进度计划编制中的关键问题之一。
