Vibration protection in railways

In the railway sector, protection against vibrations is an important concern as cracks can appear in buildings next to railway lines or above railway tunnels if no protective measures are installed. These protective measures greatly reduce the propagation and amplitude of vibrations and sound waves emitted into the ground, which can otherwise also lead to secondary airborne sound and, consequently, to noise pollution. Vibrations are caused, for example, when trains travel over rails positioned incorrectly: each time an axle crosses such a rail, the rail hits jerkily against the sleeper producing, meaning vibrations and sound waves which are then transmitted through the ballast or the track slab into the ground, where they propagate.
Another source of such vibrations is wheel imperfections, where one or more damage points per axle rotation cause irregularities in the wheel-rail contact force curve. These also have a pulse-like character and cause vibration waves in the ground in the same way as incorrectly positioned rails. Excessive vibration amplitudes are prevented by insulating the ballast bed or track slab from the ground.

Insulation is provided by an elastic layer, which is inserted between the ground and the track bed structure. The characteristics of this layer (usually an elastomer material) must be designed so that the natural frequency of this layer is much lower than the frequencies emitted by passing trains. The greater the gap between these frequencies, the more effective the insulation is. Vibrations are thus not eliminated from the system by damping, but by insulating the source. The dimensions of the vibration protection depend on the mass of the track slab and the axle loads of the trains using the line. If the dimensions are incorrect, vibrations and, consequently, unwanted negative effects may even be amplified in the track environment (resonance effects). The protective measure can be designed as a full-surface, strip or dot-shaped component but fitters must always ensure that no sound bridges are created. The top of the elastic elements absorb the vibrations. Impact penetration must be prevented, something which established products also ensure.

How mass-spring systems work

The composite consisting of a track slab, including the rail and sleeper, the elastic element and the rigid base mass, is also referred to as a mass-spring system (MSS), in which the elastic element acts as a spring. Mass-spring-systems can be designed as full-surface, strip-shaped or point-shaped with regard to their spring. This unlocks great potential in terms of tremor protection as an MSS can be optimally adapted to the permanent way.

If highly critical natural frequencies of less than seven hertz are required for vibration protection, a double layered MSS or even single bearings instead may be used. The mass and rigidity of the track (ballast trough or ballastless track) must be precisely matched to the elastomer element spring stiffness to provide vibration decoupling between the track system and the surrounding area.




Short description

Made of synthetic and natural rubber, these specially designed USM models with a unique shape are available in various designs and stiffnesses for use at all train speeds and with axle loads up to 250 kN. The conical stud mats are used to provide efficient vibration and structure-borne sound isolation in mass-spring systems to meet vibration mitigation requirements.

The USM models are manufactured using high-grade rubber blends. They have a high mechanical load capacity and are permanently weather-resistant. The mats absorb virtually no water, excel thanks to their high electrical insulation resistance and provide drainage on the mat level.

The USM series is suitable for both ballasted and ballastless track systems. Models with greater stiffness are also used as what are known as transition mats to adapt stiffness in different types of adjoining track sections.

The tests of the USM series were carried out according to DIN 45673-5 and DIN 45673-7.


  • Reduces dynamic wheel forces
  • Reduces the track and vehicle stress load
  • Cuts track maintenance costs
  • No replacements required thanks to high fatigue strength
  • Expected service life min. 60 years
  • Reduces vibrations, structure-borne sound and secondary airborne sound
  • Greater quality of life for residents in surrounding areas
  • Greater travelling comfort
  • Protection for adjacent structures and buildings susceptible to vibrations