An innovative system to reduce the noise emissions from railways has been developed by the German company Frenzel-Bau.
Called Durflex, it is based on the concept of stabilising the ballast stones under the track using an elastic polyurethane foam from Bayer MaterialScience.
The cavities between the ballast stones in the track bed are completely filled with Bayer’s Bayflex liquid polyurethane foam by a rail-mounted vehicle, which prevents the stones from shifting as a result of the forces generated when a train passes over them.
This also increases the durability of the ballast superstructure and absorbs the structure-borne noise at the point where it is generated.
The company said that the system can be used to build new sections of track as well as upgrading existing stretches.
Durflex was successfully tested on two stretches of track in
Plans include construction of a longer demonstration track in
Bayflex liquid polyurethane foam system is injected straight into the gaps between the ballast stone and foams up to fill them completely
Infrastructure managers spend millions of pounds each year cleaning the ballast to maintain the gaps between the large stones. This is because as dirt, brake dust and other foreign matter builds up, it stops the ballast draining properly, putting the railway at risk of flooding. In the past, crushed ash was used as ballast, but this suffered similar flooding problems. 150 years of trial and error has shown that the stones need to be as large as they are, and the gaps exist for good reason.