Evaluation of Construction Cost Overruns in Structural Engineering Projects in the Federal Capital Territory

Construction cost overruns are a persistent challenge in public and private sector structural engineering projects across Nigeria, leading to project abandonment, reduced structural scope, and compromised quality. This study evaluates the frequency, magnitude, and causes of cost overruns in forty structural engineering projects in the Federal Capital Territory within the North Central geopolitical zone, covering bridge construction, multi-storey building, and drainage infrastructure project categories. Data were collected through structured questionnaire surveys administered to project managers, quantity surveyors, and clients, supplemented by analysis of contract documents and final account statements obtained from the FCT Infrastructure Directorate. Cost overrun was defined as the percentage difference between the final contract sum and the original contract price. Results reveal that cost overruns occurred in thirty-two of the forty projects, with an average overrun of 47.3 percent of the original contract value. Scope changes and design revisions emerged as the most frequently cited cause in twenty-four projects, followed by material price escalation, contractor under-pricing, and unforeseen ground conditions. Projects procured through open competitive tendering demonstrated lower average overruns than those procured through direct selection, by a margin of nineteen percentage points. The study recommends adoption of design-freeze protocols before tendering, inclusion of robust provisional sum allowances for geotechnical risk, and mandatory value engineering reviews at thirty percent design completion stage for all capital projects in the FCT. Keywords: cost overruns, structural engineering projects, Federal Capital Territory, project management, construction economics.