Trackbed Isolation

Building Isolation Materials On Site

Although it is possible to reduce the amount of vibration entering a structure by treating the foundations of the building itself, there really is no better solution than treating vibration ‘at source’.
By isolating the trackbed from the surrounding material, all the properties in the immediate vicinity of the track can be protected from the potential damage caused by the vibration of passing trains.
Our Technical Sales Director, Jim Herbert, was recently asked for his expert opinion on the subject of trackbed isolation, specifically in relation to HS2, by the leading business magazine for railway managers, Rail Professional.
Good Vibrations?
The implications of HS2 remain a major concern for many at a local level, with protestors trying to stop it. Jim Herbert identifies the main noise and vibration challenges posed by high speed rail
Addressing the acoustic implications of the high speed rail link at the launch of the public consultation, transport secretary Philip Hammond ascertained that additional funds, £215m, would be allocated to reduce the impact of nuisance noise. While this may go some way to mitigating homeowners’ concerns, the adverse effect of nuisance noise caused by ground borne vibrations, as well as the source of these vibrations, will also need to be addressed to ensure the line is viable.
To tackle the challenge of railway generated vibrations on a local level, it is essential that developers take preliminary steps to seek out suitable anti-vibration solutions that will reduce disturbance to neighbouring communities.
In railway applications, ground borne noise and vibrations are generated from the movement of rolling stock. The high speed trains will travel at speeds of more than 200mph and, while this offers a considerable decrease to journey times, there are a number of vibration issues inherent in reaching such speeds that will have a notable impact on the surrounding environment.
Ground borne vibrations emanating from fast-moving trains can have a significant effect on communities, as energy generated from rolling stock is transmitted into nearby dwellings. In the first instance this can trigger perceptible movement in the building structure and nuisance noise, thereby causing considerable disturbance to occupants. To minimise the potentially damaging effect of vibration transmissions, an encompassing anti-vibration solution should be sought during the planning phase.
Isolating the problem
To reduce the impact of vibrations generated from high speed rolling stock, developers are advised to treat the trackbed area. Active trackbed isolation provides an efficient means of combating ground-borne vibrations by tackling the problem at source. Comprising a high-performing spring system, this method uses elastic interfaces to de-couple a vibrating subject from its surrounding structure, effectively isolating the dynamic force.
There are various anti-vibration products available that will accommodate a wide range of trackbed requirements. Best practice in the instance of high speed rail is to select an environmentally friendly elastomeric material that will deliver high-performing and sustainable structural isolation for the lifetime of the installation. Furthermore, this type of resilient material can be used in a number of trackbed applications, such as ballast mats, track support systems, rail pads, base plates and mass spring systems, to provide flexibility in vibration control.
While the addition of underground tunnels to the proposed route will help to alleviate the pressure to relocate tenants whose homes are located along the planned high speed rail route, these areas must also be assessed for noise and vibration issues and treated accordingly. Functioning on the same principle as active trackbed isolation, the installation of an appropriate elastomeric material to tunnels will reduce noise and vibration transmissions by isolating the source of the problem.
Where railway tunnels are adjoined to building foundations, there is a risk of sound transmission from high speed rolling stock, which can disturb occupants and compromise existing foundations. A versatile treatment, elastomeric products can be applied vertically to the tunnel walls thus providing complete isolation of the vibrating structure.
Due to the complex nature of any type of isolation, it is necessary to assess performance requirements at initial planning stage. The most effective and arguably only way to ensure that vibration is adequately controlled to reduce impact on local communities is to conduct an extensive site examination prior to the route being finalised and produce a vibration report.
Ultimately, this will allow developers to select a high performing isolation treatment at the design stage that will effectively combat noise and vibration challenges.
The most important component of any effective trackbed isolation solution is the elastomeric material. An adaptable material, such as our Regufoam or Regupol RAV products, can be incorporated into a number of trackbed isolation systems, such as mass spring systems, rail pads, base plates, ballast mats and track support systems.

Our Trackbed Isolation Products

 

Regufoam

Regufoam Vibration Isolation Material

  • Load Range 0.010-0.4N/mm2
  • Natural Frequency 8-10Hz
  • Polyurethane Foam
  • Designed to be Flexible
Regupol RAV

RAV Vibration Isolation Material

  • Load Range 0.05-1.5N/mm2
  • Natural Frequency 10-12Hz
  • Polyurethane-Bound Rubber Granulate
  • Fully Recyclable