Estimated level comfort determination on freeways in mountainous areas

Introduction. The sustainable development of mountain regions is unfeasible without the establishment and maintenance of an appropriate transportation infrastructure. The exponential growth in motorization and the expansion of settlement systems necessitate the development of a network of thoroughfares that guarantee convenient and secure mobility for individuals using private vehicles. Considering the high recreational appeal of mountainous landscapes, the creation of a highway system also contributes to enhancing the tourism potential of areas adjacent to these routes. The level of service (LOS) is a crucial metric that enables the assessment of the efficiency and quality of public transportation services. The findings of our previous research have paved the way for the development of a novel methodology for calculating LOS on roads classified as first - category, taking into account contemporary traffic conditions. However, the application of these methods in mountainous regions necessitates additional considerations related to the specific characteristics of road layout and the requirement for advanced engineering structures. This article presents the findings of research and the rationale behind the calculated LOS values for highways operating within mountainous terrains. Materials and methods. When calculating the level of service that corresponds to the maximum NPV, standard methods were used to determine the estimated costs of road construction, as used in justifying the technical and economic indicators for the operation of highways in the Russian Federation. In the construction of highways under difficult and mountainous conditions, the installation of large and expensive artificial structures is necessary. To calculate NPV, a factor p has been introduced that demonstrates how much the costs of construction, including the costs of installing artificial structures and other expenses, exceed the costs of building a road determined according to standard procedures. Results. To establish a reasonable level of service, calculations of NPV indicators were performed, their approximation was performed, cubic equations were obtained, their local maxima were determined, which correspond to the maximum NPV for the estimated service life of the structure. It has been established that with the estimated cost of construction (including artificial structures) not exceeding fifty times the standard cost of road construction, the estimated level of service is recommended to be assigned “C”, if the specified threshold is exceeded, the economically justified level of service is “D” or “E”. Discussion. The calculations and analyses have demonstrated that the level of service provided is highly sensitive to road conditions and is largely dependent on the cost of artificial infrastructure. Conclusion. In mountainous conditions, given the extremely high costs of installing artificial road structures on motorways when passing through mountainous areas (p>50.0), for the purposes of rationing the calculated level of service on motorways, it is recommended to take the level of service “D” or “E”. Resume. The studies carried out made it possible to clarify the optimal level of service for roads located in mountainous areas, which allows to improve the quality of transport services for the population and ensures the achievement of the goals of sustainable development of mountainous areas. Suggestions for practical applications and directions for future research. The completed studies allow a reasonable approach to the designation of the level of service on highways passing through mountainous areas and are recommended for their planning and design.