If CPM Is So Bad, Why Have We Been Using It So Long

Lauri Koskela1, Greg Howell2, Ergo Pikas3 & Bhargav Dave4

1Professor, School of the Built Environment. University of Salford, Maxwell Building, room 507, The Crescent, Salford, M5 4WT, UK, [email protected]; Aalto University School of Engineering, Espoo 00076, [email protected]
2Research Associate, Project Production System Laboratory, University of California
3PhD Candidate, School of Engineering, Aalto University, Espoo 00076, [email protected]; Tallinn University of Technology, Tallinn 19086, [email protected]
4Postdoc, School of Engineering, Aalto University, Espoo 00076, [email protected]


Why has the Critical Path Method (CPM) been used so widely for so long given its inability to produce predictable outcomes? For shedding light on this paradox, the formative period of the CPM is analysed from two main angles. First, how was the CPM embedded into the construction management practice? Second, what was the methodological underpinning of the development of the CPM? These questions are researched through a literature review. In terms of embeddedness into practice, it turns out that the CPM morphed from being a way of production control, into a method for contract control. In consequence, the promotion of the CPM by owners has been crucial for pushing this method to be the mainstream approach to scheduling and production control. Regarding methodological underpinning, it turns out that the CPM was developed as a way of optimization, as part of the quantitative methods movement. This movement was largely based on the axiomatic approach to research. In good alignment with that approach, there was no attempt to empirically test quantitative models and their outcomes. In this context, the unrealistic assumptions and conceptualizations in CPM did not surface in forty years. These results are argued to be helpful in critical discussions on the role and merits of CPM and on the methodologies to be used in construction management research.


Critical path method, CPM, production planning, control, construction management



Koskela, L. , Howell, G. , Pikas, E. & Dave, B. 2014. If CPM Is So Bad, Why Have We Been Using It So Long, 22nd Annual Conference of the International Group for Lean Construction , 27-37. doi.org/

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