The process of cost modeling using risk analysis for construction projects is very crucial for the achievement of project success. The purpose of this paper is to present an analysis of the financial impact of risk factors affecting key construction work sections; using a systematic risk methodology based on empirical judgment. The failure mode effect analysis (FMEA) and the evidential reasoning methods are presented as qualitative and quantitative risk tools respectively. Data analysis from structured questionnaires revealed that four work sections are prone to high scope changes contemporaneous with seven risk factors. Contrary to the usual 10% contingency estimate allowed for construction projects in Ghana, an approximate overall physical contingency range of between 13.36% and 17.88% was determined using evidential reasoning methods. The likely impact of the integrated work sections and risk factors provide a clue to estimators on how to estimate and account for project cost contingency. The research concludes by recommending a framework for improving the estimation process of cost contingency through the integration of efficient risk management strategies, cost estimation and design management process.

The process of decision making and risk analysis are essential tasks along the construction project cycle. Over the years, construction practitioners and researchers have used various methods, tools and techniques to evaluate risk and assist in making more concise decisions. Most practitioners, however, rely on their expert judgment, past experience, intuition, acquired and accumulated knowledge and gut feelings to make decisions. Aleatory (natural, heterogeneity and stochasticity) and epistemic (subjective, ignorance) are the two major types of uncertainties observed in natural sciences. Practitioners traditionally deal with aleatory uncertainty through probabilistic analysis based on historical data (frequentist approach); and epistemic uncertainty, on the other hand, handled through the Bayesian approach which has limitations since it requires a priori assumption. This paper reports the application of the DST (Dempster Shafer Theory) of evidence to determine the most critical risk factors affecting project cost contingencies using their epistemic probabilities of occurrence. The paper further discuses how these factors can be managed to enhance successful delivery of infrastructural projects. It uses the mixed methodology, with data gathered through structured questionnaires distributed to construction clients, contractors, professionals and experts in the built environment. The research revealed that design risk, financial risk and economic risk were most important cost risk categorizations. In particular, scope changes, incomplete scope definition, incomplete design, changes in specification, micro and macroeconomic indicators and delayed payment problems were identified as the most important risk factors to be considered during the cost contingency estimation process, hence successful delivery of infrastructural projects. The paper concludes by recommending modalities for managing the contingency evolution process of risk estimation to enhance successful delivery and management of infrastructural projects.