A simplified approach to the planning and control of cost and project duration

This paper presents a simplified approach to the planning and control of cost and project duration. The major decisions facing management relate to problems concerning time and cost and equally important, the intrinsic relationship that exists between them. Many attempts have been made to model these factors over the past 20 years. The majority of the models produced suffered from the mathematical complexity inherent in their structure and the consequent need for high powered mainframe computing facilities to produce a solution. The most mathematically precise models were probably those developed by Meyer and Shaffer (1965), refined by Cusack (1984). The major difficulties with these models relate to the large number of constraints and variables generated. These were subsequently reduced by Cusack (1985) by concentrating the analysis on breakthrough points on the cost curve. Although substantially reducing the computing time required the models were still generating a relatively large number of variables and constraints with, again, a consequent need for high powered mainframe computers. This approach therefore still retains many of the disadvantages referred to in the Introduction. This paper describes a heuristic approach to modelling the time-cost relationship giving near optimal solutions that take advantage of the rapid technological developments in microcomputing. The implementation of the model on a microcomputer is described which, by using a phased approach makes the size of project that can be handled virtually unlimited.