Constructing a toll road project required relatively high capital outlays and involving complicated activities. The typical of the project is classified as sensitive to risks and uncertainties. Proper risk management during construction lifecycle period may yield substantial certainties in reducing risk costs. The risk costs were calculated using stochastic analyses. The results showed that there were 7 main activities which were considered as the riskiest ones, and in need to manage such as; construction of concrete structures, road pavement, ground works, interest during construction (IDC), escalation costs, base and sub-base course aggregate, and land acquisition activities. This study identified that before conducting risk mitigation, there was 90% probability of the project costs would be at the range of IDR 23.06 Trillion to IDR 23.96 Trillion. After implementing risk mitigation, there was 90% probability the project cost would decrease at the range of IDR 21.53 Trillion to IDR 22.42 Trillion. Risk Management may reduce project risk costs systematically.

This paper demonstrates state of the arts stochastic risk analyzes in assisting decision-making processes in achieving the project objectives in terms of the estimating project costs under uncertainty. The objectives of this study were to; (i) analyze the feasibility of the Trans Sumatra toll road projects section of Medan-Binjai (25.46 km), Indonesia, and (ii) identify and quantify the toll road risk and uncertainty variables influencing the economic feasibility of the project using stochastic approach. This study identified that the risk variables in this study may include; Indonesia Certificate Bank (SBI), inflation, volume of traffic (vehicles), operation and maintenance (O&M) costs, construction costs, land accusation costs, Jakarta Inter-Bank Offer Rate (JIBOR), and design (EED/FED). The initial results of this study (Scenario 1), using concession period of a-35 years with an implementation of the initial tariff of class I vehicles (Rp. 750 / km) showed that the project was considered not financially feasible as 90% probability of the projected net present value (NPV) was negative at the range of Rp. -1.06 trillion to Rp. 2.57 trillion. The project would be financially feasibility after conducting mitigation processes for those the identified risks, such as; providing the government supports (GSs) as much as 40% of the total construction costs as well as land acquisition costs (Scenario 3). This scenario has resulted that there was 90% probability of the projected NPV would be positive at the range of Rp. 0.54 million to 1.894 million. The implementation of the stochastic risk analysis may assist the project managers comprehensively in developing decision-making processes in financing the toll road project.