| Popis: |
Scheduling software used for construction projects is generally designed to plan and monitor activities and resources. These types of software allocate resources to the different activities, and allow for resource levelling, costing and cash flow calculations. These features are well-adapted to subcontractors who manage their own human and material resources, and allocate them to the activities of one or a multitude of projects. General contractors and consultants do not generally have full control over project resources, and therefore, most software does not directly address their needs for monitoring unit- or fixed-price contracts. In addition, subcontractors’ schedule structures do not necessarily follow the logic of the Bill of Quantities which makes it more difficult to monitor financial progress and cash flow. This paper exposes the problems and limitations associated with the existing scheduling software, and presents three scheduling solutions using MS-Project and Excel individually or in combination. These methods have been applied to several case studies in irrigation and fisheries mega-infrastructure projects in Morocco and Burkina Faso. The methodology and proposed solutions are validated through their applications on these mega-projects. BACKGROUND Most activities for construction building projects are performed by subcontractors who are responsible for the implementation of the majority of these activities using their own teams, equipment, and materials. Subcontractors are also responsible for preparing the construction schedule according to their own specialties and the day-to-day activity planning. To do so, they allocate the resources necessary for the completion of these activities. Scheduling methods are generally based on critical path methods, abbreviated as CPM. These methods establish the logic between the project activities based on the networks traditionally known as Activity On Arrow (or AON) (Ford and Fulkerson, 1957), or the Precedence Diagram Method, PDM (Roy, 1962 Fondahl 1962). Resources are then allocated to these networks. Leung 2004 cites that scheduling methods deal with the allocation of scarce resources to tasks over time. Scheduling software is based on these methods by establishing logic between activities, and by allocating resources to the scheduled activities, allowing for resource levelling and costing. Using this process, the software is well-adapted for scheduling subcontractor specialities. |
