PROSE and BATEGU have succeeded in developing an environmentally friendly rail pad which considerably reduces rail traffic noise and protects the track bed.
Noise causes stress and makes people feel unwell. For this reason, the Federal Office for the Environment (FOEN) and the Federal Office of Transport (FOT) are promoting noise and vibration-reducing measures in railway construction. PROSE won the tender for a corresponding research project three years ago and brought the rubber manufacturer BATEGU on board for its implementation. Together they developed a new rail pad, which reduces the rail noise by 2 to 4 dB(A) and at the same time protects the track bed. The project has now been successfully completed with appropriate tests and the rail pad, which are made of an environmentally friendly material, can be used immediately.
Constantly growing rail traffic
In many rail networks, such as in Switzerland, the standard superstructure generally consists of concrete sleepers in the ballast bed and rails which are connected to each other via a clamping system using an elastic rail pad. Until a few years ago, little attention was paid to the rail pad. However, it is now known that the rail pad has a significant influence on track maintenance, vibrations in the track bed and noise. Hard pads are acoustically advantageous, but have low damping properties, which leads to high maintenance costs. Soft pads, on the other hand, reduce vibrations much better, but are unfavourable from an acoustic point of view. The challenge was therefore to develop a rail pad that meets both requirements: Noise and cost reduction in maintenance.
In 2017 PROSE and BATEGU started with the joint development PROSE is active in the field of vehicle design and testing and knows the systematic interrelations of track dynamics and acoustics. In this project it concentrated on as-built analysis, simulation models, laboratory tests and installation and measurements on test tracks. BATEGU is a developer of rubber compounds and manufacturer of damping elements for use in rail vehicles, machines, automobiles, aircraft and ships, among others. It contributed the know-how for the development of a suitable material and the design of the rail pad.
It is audibly quiet
After successfully completing laboratory tests, which proved that the newly developed material or the rail pad absorbs the vibrations occurring on the track in the best possible way, tests were carried out in the field: on a 200 m long track section of the SOB and BLS with both rail profiles (UIC54, UIC60). In the case of the SOB, the focus of the tests was on the acoustic effect in tight curves and in the case of the BLS on the acoustic effect in the mainline railway area.
The spontaneous remark of a neighbour who was on site during the noise measurements that it had become audibly quieter already indicated that the new rail pad significantly reduced the driving noise.
The measurements with the new rail pads showed a measured noise reduction of up to 4 dB(A) compared to the conventional soft rail pads used so far. And the static low-frequency properties are almost identical. System tests in accordance with EN 13481-2 and a large number of other tests also demonstrated that the new rail pads also meet the requirements for continuous use and resistance to ageing. Therefore, with the installation of the new rail pads, noise can be significantly reduced and at the same time the loads transferred to the ballast bed can be kept to a minimum and maintenance costs kept low.
Environmentally friendly material
When selecting the raw materials to be used for the material, the material developers were particularly concerned to meet current environmental requirements. This goal was also achieved: The new material or pad is free of nitrosamine-forming raw materials and meets the strict RoHS guidelines, the REACH requirements and the UNIFE (Railway Industry Substance List) guidelines. The new developed rail pads by PROSE and BATEGU are therefore ideally suited for the application and meet the mentioned requirements in an optimal way.