Delays in Construction Projects: Causes, Effects, and Mitigation — A Thematic Literature Review

Construction project delays remain one of the most persistent problems confronting owners, contractors, and consultants worldwide. This literature review synthesizes findings from ten selected studies (1987–2023) to develop a coherent picture of the principal causes of delay, their effects on cost and quality, the interrelationship between delays and conflicts, and current mitigation strategies. Using a thematic synthesis approach, the review identifies recurring drivers — design changes, poor communication, financial constraints, contractor capability, and supply-chain issues — and highlights promising mitigation measures including improved early-stage planning, enhanced supervision, integrated stakeholder coordination, and quantitative modelling tools. The review concludes with gaps in the literature and directions for future research.