Risk Quantification in Construction Project Management Using Monte Carlo Methods: Evidence from Abuja FCT Projects

Construction projects in the Federal Capital Territory, Abuja, frequently exceed their planned budgets and schedules due to inadequate risk quantification during the project planning phase. This study applies Monte Carlo simulation methods to quantify cost and schedule risk in three completed public infrastructure projects in the FCT, North Central zone: a road rehabilitation contract, a school construction project, and a government office building. Historical project data including tender sums, final contract sums, planned durations, and actual durations are obtained from the FCT Infrastructure Development Authority for projects completed between 2019 and 2023. Risk registers are developed through structured expert elicitation, identifying 22 cost risk events and 18 schedule risk events with probability and impact distributions. The @Risk software package is used to execute 10,000 Monte Carlo simulation trials, generating probability distributions of total project cost and duration overrun. Results indicate that the 80th percentile cost at completion exceeds the contract sum by 31 percent on average across the three project types, with material price escalation and design change orders as the dominant contributors to cost risk. Schedule risk analysis identifies regulatory approval delays and contractor cash flow constraints as the primary drivers of timeline overrun. The study recommends mandatory risk-adjusted cost estimation with Monte Carlo-derived contingency reserves for all FCT public projects exceeding 500 million naira. Keywords: Monte Carlo simulation, construction risk, project management, Abuja FCT, cost overrun.