Cost overruns are common on government and commercial projects. This paper proposes a cost risk estimating method that provides more accurate estimates of total project cost and answers the following important questions: (1) What is the most likely cost? (2) How likely is the baseline cost estimate to be overrun? (3) How much contingency is required on the project to guarantee that the total project cost is not to be exceeded, with a certain confidence level? The proposed method is based on the Monte Carlo simulation. It helps gain better information than traditional cost estimating methods, mainly because it recognizes that project costs are uncertain. A fictitious case study was developed to provide a structured way to provide the contingency value of a project in order to avoid cost overruns. Data were collected on low, most likely and high possible costs and the @Risk software from the Palisade Corporation was used to run the Monte Carlo simulations. Using a simplified cost case study, this paper demonstrates how Monte Carlo simulation can assist project managers in estimating the contingency to be allocated to their project, and contribute to fostering and bolstering the credibility of risk analysis results.
contingency, cost estimating, cost overruns, monte carlo simulation, risk analysis
 Auger, M., Procurement organizations: a global comparison, economics, resources and international affairs division – parliamentary information and research service, publication N0. 2014-82-E, Ottawa, Canada, pp. 4–10, 2014.
 Flyvbjerg, B., What you should know about megaprojects and why: an overview. Project Management Journal, 45(2), pp. 6–19, 2014. http://dx.doi.org/10.1002/pmj.21409
 Younossi, O., Arena, M.V., Leonard, R.S., Roll, C.R., Jain, A. & Sollinger, J.M., Is Weapon System Cost Growth Increasing? A Quantitative Assessment of Completed and Ongoing Programs, RAND: California, US, pp. 44–46, 2007.
 Flyvbjerg, B., Holm, M.S. & Buhl, S., Underestimating costs in public works projects: error or lie? Journal of the American Planning Association, 68(3), pp. 279–295, 2002. http://dx.doi.org/10.1080/01944360208976273
 AACE (American Association of Cost Engineers), AACE International’s risk management dictionary. Cost Engineering, 42(4), pp. 28–31, 2000.
 Ministry of Transportation and Infrastructure (MOTI), Project cost estimating guidelines, Version 01.02, Victoria BC, pp. 8–10, 2013.
 Baccarini, D., Understanding project cost contingency – a survey, Cobra International Construction Conference, Brisbane, 2005.
 Mak, S., Wong, J. & Picken, D., The effect on contingency allowances of using risk analysis in capital cost estimating: a Hong Kong case study. Construction Management and Economics, 16, pp. 615–619, 1998. http://dx.doi.org/10.1080/014461998371917
 Baccarini, D., Estimating project cost contingency – beyond the 10% syndrome. Australian Institute of Project Management Conference, Victoria: Australian Institute of Project Management, 2005.
 Project Management Institute, A Guide to the Project Management Body of Knowledge (PMBok), 4th edn., Project Management Institute: USA, 2008.
 ACCE International, Cost estimate classification system – as applied in engineering, procurement, and construction for the process industries, Recommended Practice No. 18R-97, TCM Framework: 7.3 – Cost Estimating and Budgeting, 2011.