Content area
Full text
ABSTRACT:
In many projects, including construction projects, managers are confronted with the need to compress or accelerate a schedule. An important aspect of this is activity crashing, or the reduction of activity time by the addition of resources, such as workers and overtime. In these situations it is important that managers determine the optimal crash plan to complete the project, within the desired time period. In this article, the authors discuss crash costs in detail, and how to calculate them in practice. It is also argued that the crash cost model is badly understood and consequently not used in practice. Only under certain assumptions with regard to activity duration versus resource use is it possible to revitalize the model as a representation of reality.
KEY WORDS: Crash costs, project management and project scheduling
(ProQuest-CSA LLC: ... denotes formulae omitted.)
Network crashing was originally developed along with the critical path method (CPM) for planning, scheduling, and controlling large scale projects. CPM was developed in the 1950s. Project crashing is a term given to the method by which project duration can be reduced, preferably at the least additional cost.
The method is also known as "project expediting," "least-cost scheduling," and "schedule compression" [2]. For simplicity we will use the term "crashing" in this article.
Crashing is applicable in situations that require a project to be completed earlier than expected, and where cost control is important. Customer requirements to accelerate completion because of rising loss-of-opportunity cost are an example. Crashing also applies to situations where schedule delays have forced a completion date extension, and project management measures are required to reinstate a more reasonable project time frame. This is important to engineering management because projects in this field are often confronted with strict schedule control and the need for schedule compression.
The idea of network crashing in CPM is to find which activities should be crashed with the use of additional resources if the duration of the project must be shortened [1]. Crashing means selecting the lowest cost slope activity or activities, which will shorten the critical path(s). When activity durations are shortened by crashing, their direct costs increase. When the overall project is shortened, its indirect cost decreases. Then the goal of crashing is to accelerate...