Field test: new rail screen
PROSE tests and evaluates a new rail screen as an alternative to conventional technologies for rail-noise atten-uation in Switzerland.
In October 2015, PROSE conducted tests of the new Calmmoon Rail technology, which provides a rail screen to absorb noise. The rail screen is a product of Japanese manufacturer Sekisui Chemical. Sekisui is known world-wide for its “plastic wood“ sleepers of fibre-reinforced foamed urethane (FFU).
In consultation with the Swiss railway company BLS AG, the Swiss Federal Office for the Environment (BAFU) and the Swiss Federal Office of Transport (BAV), PROSE measured the acoustic effects of the rail screen in a field test between Kerzers and Müntschemier, at a site where PROSE measures rail-vehicle noise.
On this line section, during a previous complete track renewal, BLS had installed new sleepers, soft rail pads and new rails. On a 200-metre section, however, they left the older sleepers and hard rail pads. This allows in-vestigation of noise levels on both hard and soft rail pads.
Unlike rail dampers affixed to the rail web, which reduce rail vibrations, the Calmmoon rail screen technology attenuates noise coming from both the web and foot of the rail. In the course of a three-hour night period without trains, Rhomberg Sersa Rail Group, which specialises in track work, installed the rail screen elements on two 80-metre sections of track; rail pads were soft on one section and hard on the other. This was the first time Rhomberg Sersa had installed the rail screens.
Immediately before and after the installation of the rail screen elements on this single-track line section, PROSE measured the noise emissions of all passing trains, the track decay rate, rail roughness and the transfer func-tion.
The measurements showed that the Calmmoon rail screen reduced noise by up to 2.4 dB on the hard rail pads and 3.8 dB on the soft ones. These positive results fulfilled expectations for the rail screen. The fast and simple installation of the rail screen elements also impressed participants. PROSE’s measurement campaign contribut-ed significantly to the evaluation of this alternative technology. The tests also allowed evaluation of opportuni-ties offered by new track components and investigation of additional potential to reduce railway noise. Analy-sis of the measurements will now support comparisons of different standards and development of recommen-dations for the practical implementation of new track technologies.