In construction projects, risk is an event or occurrence in uncertain conditions and in case of happening risk, it has positive or negative effects on projects' goals. It should be mentioned that all uncertainties in projects don’t lead to risk; therefore, it is evident that just a limited subgroup of all uncertainties in a project is considered as the risk of project. In the present research, a risk evaluation process is proposed to determine the likelihood of risky construction projects. At the first step, four kinds of risks were identified which are very important in the project of installing a weight in motion system. Using multi-criteria decision-making technique and fuzzy number (triangular fuzzy number) as well as pair-wise comparison of the risk components, the overall rate of risk has been evaluated utilizing the proposed method. Next, in order to quantify fuzzy numbers the likelihood of risky project was calculated by the possible method of binomial Probit. Questionnaires containing risk instances and their importance have also been used for gathering necessary information according to experts' opinions about an operating system in Isfahan- Naeen road which has been selected as case study. Results revealed that the proposed method is capable to evaluate the level of risk in construction projects.