Anti-vibration tracks – Improved soft twin block tie systems
The classic twin block ties in rubber boots have become a very popular track design because of its simplicity of installation and its reasonably good vibration isolation characteristics. However, for highly resilient configuration, it presents a major problem: due to the form of the concrete blocks, it is not free to move downward, leading to inefficiency in vibration mitigation.
The D2S International soft twin block system retains the simplicity of installation of the conventional system, but integrates readily available standard concrete dual block ties as used for ballasted track, and offers a significant improvement in vibration isolation thanks to a highly resilient tie pad coupled with a specially designed rubber boot.
This system is adapted to all kinds of lines: train, commuter rail, metro, tramway, …
Performance
- 6 dB gain in vibration isolation over the classic twin bloc tie system;
- vibration isolation close to floating slab at a fraction of the cost;
- friction free vertical displacements;
- stable track conditions;
- simplicity of installation and replacement;
- standard dual bloc ties for track on ballast.
Brussels Metro, Erasme Hospital station
A recent extension of Brussels metro passes in a tunnel close to Erasme Hospital. In order to limit the vibrations to levels allowable in such a sensitive building, it was necessary to use efficient soft twin bloc tracks. Vibration levels in exploitation are so low that they can not be measured at grade.
Brussels, HST tracks - Midi Station
D2S International improved soft twin bloc ties were also used for the High Speed Tracks in Brussels Midi Station.
A major concern in the track study was the noise level in the station hall under the tracks. The station hall is an existing steel structure on top of which the tracks are to be installed. Concrete twin bloc sleepers with elastomeric pads are used for rail fixation.
A new concept (DS-ISO-Rail system, i.e. alternation of pad stiffnesses under the sleepers) had to be introduced to limit the static displacements of the rail.