A model for Incremental enhancement of the operational speed in railways based on scenario planning, Case study: Tehran-Miyaneh railway

Geometrical and topographical constraints are of the most important difficulties against the implementation of the high speed railways. This paper examines the possibility of establishing a gradual-based strategy for speed enhancement of the existing railway lines, in the areas with design constraints. Accordingly, an incremental methodology is proposed in which a railway line is divided into the various segments with different sub-regional conditions. This strategy is used to improve the speed, capacity and to reduce the travel time. The Tehran-Miyaneh railway line is selected as a case study, that with problematic geographical circumstances. The empirical Davis equation is used to determine the capacity of the railway line in which the capacity is defined in terms of the maximum number of trains that can pass from a particular rail section. The design speeds and capacities of different blocks are calculated for the selected case study. Considering the priority of the critical blocks, the enhancement of capacity and speed is studied for the case study. The results of operational conditions are obtained for the enhancement scenarios and compared with that of the basic scenario. The relationship between capacity and travel time is determined and compared for various speed intervals. The capacity of the route is increasingly enhanced by the incremental speed enlargements in different scenarios.