Cumulative Resource Constraints, Essay Example

Abstract

The complexity that arises in resource-constrained project scheduling is a consequence of the interaction amongst the activities of the project by implicit and explicit dependencies, which may be subject to varying degrees of uncertainty (Aslani, 2007).

Introduction

A project is a significant one-time activity committed to well-defined objectives and involves considerable amounts of resources. Resource allocation is one of the most contentious and complex issues in management of projects, usually as a consequence of multiple interfaces between project activities. Resource availability constraints are a typical scheduling problem in projects; a problem that limits a project manager’s ability to execute and deliver the project as per the original plan. It is, thus, imperative that project schedules must have appropriately designed project logic networks (successor/predecessor data as well as activity durations). They also require resource assignments (cost inclusive) for every activity in the network in order that the effects of resource constraints can be effectively accounted for. Activity prioritization in a project is subject to limited resources, and as a consequence, the complexity of resource allocation is normally driven by the interactions between project activity dependencies and resource constraints (Senouci & Eldin, 2004). Various models such as the resource constrained critical path method technique (RCPMT) the resource-constrained scheduling (RCS), Critical Chain Method (CCM), and the Critical Path Method (CPM), are employed in diverse project. Such models are utilized in to order to take full advantage of the utility value for every one activity with the intention that the resource allocation among competing activities, results in the minimum overall project duration.

Complexity of Resource Allocation and Interactions Between Project Activity Dependencies and Resource Constraints

In projects, concurrent activities compete for the same resources. This brings about the need to execute these activities sequentially; a necessity which may consequently have negative effects on the project’s duration if these activities be critical or near-critical. The allocation of constrained resources to individual activities is determined by use of an algorithm that maximizes the utilization of available resources, defined as maximizing the utility index in the least amount of time. The utility index of a particular resource for any activity is the ratio of the quantity of that required resources for the specific activity to the total amount required of that resource for all the competing activities (activity dependencies). If there are multiple inadequate resources required by two or more project activities, the resource with the smallest amount of production rate becomes the driving resource in resource allocation (Senouci & Eldin, 2004).   This is the essence of project scheduling since the intricacy of allocation of resource is driven by the interactions between dependencies in project activities and resource constraints. This requires analytical tools for scheduling activities and resource allocation. Modern methods involve priority-rule heuristics, (truncated) branch-and-bound procedures, and various types of evolutionary and local search algorithms. In the case of time-constrained project scheduling, efficient feasible direction methods, and network flow algorithms and are employed (Kerzner, 2003).

The complexity that arises in resource-constrained project scheduling is a consequence of the interaction amongst the activities of the project by implicit and explicit dependencies, which may be subject to varying degrees of uncertainty (Aslani, 2007). The explicit dependencies are consequences of maximum and minimum time lags between the commencement times of activities resulting from organizational or technological requirements. The scarcity of the resources employed establishes implicit dependency amongst activities, which can thereby formulated as resource constraints. In the latter case, this is referred to as a resource leveling problem (Lu, 2003). The scarce availability of resources necessitates the definition of supplementary precedence relationships between project activities. This sequencing dilemma forms the nucleus problem of project planning. Time-constrained scheduling consists of; analyzing the project schedule in a manner that all precedence relationships and time lags are observed, and some predetermined objective function is optimized.

References

Aslani, P. (2007). Dynamic Resource-Constrained Scheduling, Ph.D. thesis, Department of Civil Engineering, Polytechnic University, New York.

Kerzner, H. (2003). Project Management: A Systems Approach to Planning, Scheduling and Controlling, New York, John Wiley & Sons.

Lu, M., &Li, H. (2003). “Resource-Activity Critical-Path Method for Construction Planning”, J.Constr. Eng. Manage. 129, pp. 412–420.

Senouci A. B. & N. Eldin. (2004). “Use of Genetic Algorithms in Resource Scheduling of Construction Projects”, Journal of Construction Engineering and Management, ASCE, vol. 130(6), pp. 869-877.