Time Predictability of the UK Construction Sector: the EPT-PEM Model for Improving Project Planning Effectiveness

Abstract

Project planning time-predictability is critical to project time-performance, yet it remains persistently low in the construction sector. Improvements in time predictability offer opportunities to enhance project efficiency and delivery outcomes. The aim of this work was therefore to address construction time performance by improving time predictability. This is achieved by applying Extended Prospect Theory in a construction planning context. The research investigates the variables that influence project time-performance, identifying the planning approach and cognitive biases as central affecting matters. Whilst prior efforts have focused on project-level metrics, this work instead analyses time-predictability at an activity-level to detect performance trends. Adopting a pragmatist philosophy, a mixed-methods study was conducted. This involved the quantitative analysis of over 35,000 lines of activity level construction programme data, combined with qualitative semi-structured interviews with construction professionals. Descriptive and inferential statistical analysis was applied to the programme data, examining variables such as project type, duration, and level of detail. In addition, reflexive thematic analysis was used to interpret qualitative survey data. The combined analysis revealed significant variability in activity-level predictability. Over one-third of planning predictions fail to achieve their planned Start Date, Finish Date, or Duration, whilst fewer than one third of activities achieve accurate Start Date predictions. The interviews confirmed an industry-wide expectation of poor time-performance, with planning influenced by overambitious targets and optimism bias. The research revealed a previously unquantified empirical pattern of declining time-performance accuracy after approximately 40% of a project’s timeline, offering new evidence of how optimism bias manifests in practice, consistent with the behavioural mechanisms recognised in Extended Prospect Theory. The research findings informed two key contributions: an evolved set of Planning Effectiveness Metrics (PEMs) to support the future measuring of planning performance in practice, and the development of the Extended Prospect Theory–Planning Effectiveness Metrics (EPT-PEM) model. The model illustrates the relationship between time-predictability and optimism bias to support more realistic planning on future projects, improving overall construction delivery time performance.

Date of Award	29 Oct 2025
Original language	English
Awarding Institution	Northumbria University
Supervisor	Barry Gledson (Supervisor) & David Greenwood (Supervisor)