A comprehensive near-optimal, cost-based planning method for construction projects

Abstract

Planning and scheduling is the backbone of successful project delivery, since every project is unique and has many different factors which can determine the success or failure of the project. Meeting project delivery deadlines is generally among the greatest challenges in construction. Therefore, most of the available and commonly-used methods and tools are based on time. However, many other factors contribute to the success of a project. This research presents a planning method that examines different plans and identifies near- optimal least cost plans. The various plans differ in terms of the time between successive activities (lags and leads) and the duration of each activity (crashing and relaxation), while strictly preserving the predefined sequence of construction activities. The least cost near optimization is achieved through identifying and incorporating key factors affecting project cost. The project cost is calculated through specifically-developed equations to assess key identified factors, such as present value of cash flow, idle resources (resource-leveling), risk, and financial factors such as interest rates, retention rate and period, down payment percentage, liquidated damages, and bonuses. To fairly assess each factor's effect, the factors are monetized. Based on this, a schedule is presented to achieve a near-optimal, lowest-cost project plan. Since numerous alternatives are available to schedule a project, evolutionary algorithm is utilized to determine near-optimal solutions that fulfill pre-established objectives of the user. A case study is constructed and analyzed to demonstrate how the method works, and it illustrates its capabilities the method proves to work effectively, since it is tested through multiple scenarios, including the lowest-cost, near-optimal plan which demonstrates an increase in profit of 3.72% of the total project value and completion of the project with 11.39% shorter duration. The method can be applied by planners during the planning stage; it can also be adopted while developing acceleration plans during the monitoring and control phase of projects.