Design of longitudinal profile reconstruction with justification of longitudinal slopes

Abstract

In high-speed traffic, to ensure passenger comfort, more stringent requirements are imposed on the line plan: curves of small radii, lengths of straight inserts and transition curves, which are increased to stabilize the rolling stock. Intersections with highways are carried out at different levels, turnouts are replaced, passenger platforms are rebuilt. In addition, the devices of the central blocking and communication system are being modernized, the contact network and traction substations are being strengthened, and measures are being taken to protect the environment. However, paying attention to the line plan, curved sections, curve radii and the superstructure of the track, the influence of the existing longitudinal profile slopes on the implementation of high-speed traffic is not always taken into account. When the train moves along the fractures of the longitudinal profile, additional forces  appear in the train in addition to traction and braking forces, their magnitude depending on the mass of the train, the speed of its movement and the algebraic difference of the slopes forming this fracture ∆i. With increasing of train speeds, the profile of the existing section must meet current regulatory requirements. Thus, the greatest longitudinal slope on high-speed lines should not exceed 18 %. The longitudinal profile should be designed as long as possible with the smallest possible difference in the mating slopes of adjacent elements. The greatest algebraic difference in the slopes of adjacent profile elements [∆i] should be no more than 6 ‰ for a high-speed section of the railway. All of the above regulatory requirements put the implementation of plans for the introduction of high-speed train traffic "at a standstill". For example, in the Gomel-Minsk direction (along the entire direction of 300 km sections with the difference of neighboring slopes greater than 6 % turned out to be about 147 km or 49%). All these sections require redesigning and the use of slopes with the difference Δi ≤ 6‰, which in turn constrains the increase in speed.