The vicious circles of parallelism

Terence Williams, Colin Eden, Fran Ackermann, Andrew Tait

Research output: Contribution to journalArticlepeer-review

48 Citations (Scopus)


Manufacturing development projects are frequently highly parallel and time-constrained. A study was undertaken of such a project as part of a delay and disruption (D&D) litigation to show the effects of delays and in-development product enhancements. The use of the cognitive-mapping technique revealed some key vicious circles, and in particular that increasing crossrelations between concurrent activities increases activity durations, which under time constraints causes activities to become more parallel and hence increases crossrelations. System dynamics was used to model these loops quantitatively, explaining the level of D&D experienced within the project, which was more than the sum of each individual causal effect as the effects compounded each other. A case study is used as a basis to analyse these effects, and discuss the wider implications for modelling projects for which project networks are the normal modelling medium, and possible ways in which the inadequacies of networks can be overcome.
Original languageEnglish
Pages (from-to)151-155
Number of pages5
JournalInternational Journal of Project Management
Issue number3
Publication statusPublished - Jun 1995


  • vicious circles
  • parallelism
  • delay and disruption
  • litigation
  • system dynamics


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