Ballastless Tracks on Asphalt Pavements

- Design and Experiences in Germany –

Abstract

During the last three decades different types of ballastless tracks have been developed, tested and built in high speed lines of the German DB-AG.:
- single rail supports directly fixed on a pavement (CRCP only).
- prefabricated, prestressed slabs or frames connected to a treated base
- sleeper panels rested on a pavement (AC or CRCP) or connected in a monolithic way (CRCP only)

The axle loads of railway vehicles are much higher compared to heavy trucks. But due to the good load distribution reached by rail and resilient rail supports and due to a sufficient contact
area between sleeper and treated base the contact pressure on pavement surface can be decreased. Therefore asphalt pavements offered suitable solutions for ballastless track
developments. The concrete sleeper panel must be fixed by suitable components to the asphalt pavement to handle the horizontal forces caused by traffic and by temperature changes. The weight of sleepers should be considered in respect of rail uplift forces. In addition to the bearing capacity for asphalt pavements the occurrence of deformations caused by the time and temperature dependent visco-elastic behaviour of asphalt must be taken into consideration. Due to the accuracy of the vertical track-alignment according to the design speed up to 300 km/h and more and due to the sufficient surface drainage the deformations must be limited, but enable better adaptation at the interface between sleeper and pavement. Experiences born at test sections and revenue lines are given.