Vibration Isolation of Rail and Transit Systems

Summary: Mass transport systems often require vibration and structure-borne noise control in inner city, residential and office areas to ensure the comfort of the occupants.

Urban areas are nowadays only attractive for people, if they offer certain facilities. These facilities include short and fast transport links to and within that area. Fast links can be provided by mass transport, but surface level tracks for mass transport can limit the access and movement of individuals. Bridges and tunnels are necessary, otherwise crossing the track becomes dangerous and time consuming. It is, therefore, preferable to leave the surface space track free and to move mass transport into tunnels or to elevate them. A positive side effect of this is that transit distances can even be shortened. It is also a good idea to modify, for example, terminals into transit stations as projected in “Stuttgart 21”, “Frankfurt 21” or the “City Tunnel Leipzig”.

Such measures move the transport systems right next to residential and office areas. Since the wheel- rail contact of the trains causes noise and vibration, which are transmitted via the subsoil and the foundations into the neighbouring structures, mitigation measures are often necessary to reduce this transmission to acceptable levels.

A very effective way of achieving this is to elastically uncouple the vibration source and surroundings, using for example, helical springs. This can be done either at the source or as a base isolation system for the buildings.

At the source, floating trackbeds provide the best results. They consist of the base, the trackbed and the spring elements as an interface (see picture 1).

Pic. 1: Arrangement of GSIV Elements in a Two-Track Tunnel