Dynamic simulation of the V-Tras ‘superstructure’ transition solution

Description

The V-Tras transition system, designed by Romberg Sersa, consists of a steel ladder type module between the sleepers and ballast layer. This module hinges off the slab track, but rests freely on the ballast. The bending resistance of module reduces towards the free end. The performance of this transition, when transitioning from slab to ballasted track, is investigated using a finite element model consisting of solid elements around the V-Tras module and simple (beam, dashpot, spring) track representations throughout the rest of the model. For comparison, a baseline case with no V-Tras module or other transitions counter-measures is also developed. Static analysis determined the pressures at the ballast-sleeper interface in both cases. It was found that V-Tras significantly reduces ballast pressures compared to the baseline case. Static analysis was also used to determine equivalent track stiffness profiles in both cases. Finally, vehicle-track interaction software was used to investigate the wheel-rail contact forces. Transiting from a very soft fastening on slab track to a stiff fastening on ballasted track introduces a high stiffness gradient when no counter measures are in place. The V-Tras system was found to increase this stiffness gradient slightly, but increase contact forces only marginally. However, further step changes in stiffness were introduced by ‘zoning’ the USP stiffness along the V-Tras length. This has the beneficial effect of reducing the peak stiffness gradient.

Period	2018
Event title	The Fourth International Conference on Railway Technology: Research, Development and Maintenance
Event type	Conference
Conference number	4
Location	Sitges, Spain
Degree of Recognition	International