Time–cost combined optimization in planning infrastructure construction projects under environment induced time‐window constraints

To accommodate environment-induced time-window constraints, environment-sensitive activities are arranged within allowable time windows while maintaining technological precedence and other logical relationships on the project. This research advances classical time–cost trade-off (TCT) analysis by incorporating time-window constraints in project planning, creating a more complex optimization problem that becomes computationally prohibitive for real-world applications. To overcome this challenge, an integrated project planning framework combining project time and cost into a single objective function is formalized. The optimization solution employs time-window scheduling algorithms to simulate method combinations through enumerated simulation. A reward function is defined to evaluate alternatives based on their impact on project cost and duration. In addition, a sample size reduction technique is utilized to maintain computational efficiency of random sampling without sacrificing accuracy. The methodology's practical application is demonstrated through a case study of a river-crossing bridge project in remote northern Canada, which is planned to validate its effectiveness in planning real-world infrastructure projects under stringent environment-induced time-window constraints.