  In construction projects, contingency reserves have traditionally been
estimated based on a percentage of the total project cost, which is arbitrary
and, thus, unreliable in practical cases. Monte Carlo simulation provides a
more reliable estimation. However, works on this topic have focused exclusively
on the effects of aleatoric uncertainty, but ignored the impacts of other
uncertainty types. In this paper, we present a method to quantitatively
determine project cost contingency reserves based on Monte Carlo Simulation
that considers the impact of not only aleatoric uncertainty, but also of the
effects of other uncertainty kinds (stochastic, epistemic) on the total project
cost. The proposed method has been validated with a real-case construction
project in Spain. The obtained results demonstrate that the approach will be
helpful for construction Project Managers because the obtained cost contingency
reserves are consistent with the actual uncertainty type that affects the risks
identified in their projects.
