The effects of design changes and delays on project costs

Williams, Terence and Eden, Colin and Ackermann, Fran and Tait, Andrew (1995) The effects of design changes and delays on project costs. Journal of the Operational Research Society, 46 (7). pp. 809-818. ISSN 0160-5682 (

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This paper describes a study of a large design and manufacture engineering project, undertaken as part of a Delay and Disruption litigation. Design changes and delays in design approval would have caused delay to the project; in order to fulfil a tight time-constraint, management had to increase parallel development in the network logic, reducing delay but setting up feedback loops that markedly increased total project spend. Cognitive mapping was used to elicit the relationships, which suggested the use of System Dynamics to quantify the effects. Results are described that show the effect of levels of design changes and approval delays, and their compounding effect. The wider implications on modelling projects are also discussed.