1.1 BACKGROUND OF THE STUDY
Time impacts are inevitable on construction projects, primarily because of the uniqueness of each project and the limited resources of time and money that can be spent on planning, executing and delivering the project.
Time factors are inherent in all of project construction undertakings. Construction projects have long been recognized as particularly cost, time and risk-laden. Some of the time and cost factors associated with the construction process are fairly predictable or identifiable; others may be totally unforeseen. The constructed project may not perform as anticipated because the owner may have unrealistic expectations regarding the delivery time of construction forcing contractors into unrealistic gambles, corner-cutting or commitments that may not be realistic (Frimpong 2003).
Project success can be defined as meeting goals and objectives as prescribed in the project plan. A successful project means that the project has accomplished its technical performance, maintained its schedule, and remained within budgetary costs. Project management tools and techniques play an important role in the effective management of a project. Therefore, a good project management lies in the management tools and techniques used to manage the project. Project management involves managing the resources workers, machines, money, materials and methods used. Some projects are effectively and efficiently managed while others are mismanaged, incurring much delay and cost overruns and negatively affecting the economy (Frimpong 2003).
Assessing construction projects delivery time is critical in today market-driven economy.
To improve the economy and maximize long-term return on this public investment, government agencies have recently started utilizing new types of contracting methods that are designed to achieve multiple project objectives, including minimizing construction cost and duration, while maximizing its quality.
In recent years, many departments of transportation, in various states have started to apply new highway contracting methods, including: Bidding on time i.e., to encourage competition among contractors to minimize project duration (Holt et al 2000), Incentive/ disincentive contract clauses that provide financial incentives to reduce construction duration, Night time construction that seeks to cut service disruption and project time by requiring contractors to work during off-peak night time hours, Warranty contracting that attempts to improve construction quality by making contractors liable for the performance of the facility after project completion. These new and emerging contracts place an increasing pressure on decision makers in the construction industry to search for an optimal/near-optimal resource utilization plan that minimizes construction time while maximizing its quality. This creates new and pressing needs for advanced resource utilization models that are capable of optimizing the multiple and conflicting objectives of construction time, cost, and quality.
Significant research advancements have been made in the area of optimizing construction resource utilization. This led to a number of optimization models. These models can be classified according to their optimization objectives into models that attempted to:
â€¢ Minimize project time and/or improve resource utilization;
â€¢ minimize time and cost for non-repetitive construction using time-cost trade-off analysis
â€¢ minimize time and/or cost for repetitive construction
While the above research study seeks to provide significant contributions to the area of optimizing construction resource utilization, there has been little or no reported research focusing on multi objective models for optimizing construction time, cost, and quality.