عنوان مقاله [English]
Considering the importance of freeways in connecting urban settlements and their role as the country's main road transportation infrastructure in the development of settlements, a new risk-based modeling for optimal decision-making about the choice of construction and operation strategy - Pickup from freeways inside the country is provided. Maximizing the net present value of the profit for the general society is the function of the main goal. Here, the net present value of freeway projects is determined according to the project's income flow and costs as a criterion for choosing a public-private or traditional strategy. The freeway factors affecting the model include the length and number of freeway lanes, duration of private sector participation, elasticity of demand, traffic volume ceiling, annual inflation rate, annual traffic volume and peak hours for parallel axes, toll avoidance percentage, annual toll rate, interest rate Without annual risk, the annual discount rate of the public and private sectors, the economic growth and the annual population of the country, the economic growth and the population of the two provinces that are connected by the freeway. The amount of increase in duty rates, loans and private sector taxes are considered. The volume of demand for traffic during the operation of freeways as an uncertainty and the corresponding risk of income reduction is entered in the proposed model through the probability tree scenario and the genetic algorithm is used to solve it. In order to validate the proposed model, numerical studies are carried out on Khoramabad-PulZal, Qom-Markazi, PulZal-Andimeshk, Ahvaz-Bandar Imam and Isfahan West freeways in the presence and absence of uncertainty in traffic demand forecast. The results of the simulation prove the fact that the net present value of a freeway project is affected by the predicted values of the probability and intensity of the occurrence of exploitation scenarios, and on the other hand, the duration of participation is an important factor that can greatly affect the profit. The private sector and their motivation to participate should be effective and the increase of this period of time will bring maximum benefits for the private sector.