Beyond Deterministic Scheduling: A Probabilistic Framework for Forensic Delay Analysis in Major Engineering and Infrastructure Projects

This thesis addresses the persistent challenge of accurately quantifying delays in engineering and infrastructure projects. Its particular focus is prospective delay analysis, which is central to decisions on Extensions of Time, acceleration, mitigation, and wider project recovery. Despite decades of practice and research, forensic delay analysis still remains something of a ‘dark art’. It is often difficult to explain, heavily dependent on deterministic methods, and poorly equipped to reflect the uncertainty that exists in project schedules. This creates a false sense of precision and can lead to decisions that appear robust but are, in reality, insufficiently informed.

While the literature provides extensive discussion of delay causes and consequences, much less attention has been paid to how delay should actually be measured. This creates a practical paradox – delays are widely recognised, categorised, and explained, yet their measurement remains methodologically weak. This research responds to that gap by proposing and validating a hybrid methodology that integrates Time Impact Analysis with Quantitative Schedule Risk Analysis. The aim is to show that, by combining tools already familiar to industry, delays can be measured more realistically while also supporting earlier and better-informed mitigation.

The research is delivered through three interconnected studies: a systematic literature review, a focus group with senior practitioners, and the development of an eight-step protocol for probabilistic delay assessment. The study contributes to practice by repositioning delay analysis from a reactive, dispute-driven exercise towards a proactive and strategic project-control tool. It also contributes to theory by bridging forensic delay analysis and schedule risk analysis.