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.