Birlinghoven, Germany - In future, train travel may become quieter, as that familiar clickety-clack of the train wheels passing over the railway track becomes much more muted. A new polyurethane foam system for filling all the gaps between the stones in railway track ballast gives major benefits in reducing air- and structure borne noise and raising stability, its developers claim.Following promising lab and test-track trials, a foamed track section has been installed into the main intercity line 1720 from Hamburg to Hanover, near Bad Bevesen-Uelzen. "Once rail traffic in this section recommences, we expect the real-life results to prove the reduction of the above-mentioned parameters," commented German polyurethane machinery company Hennecke GmbH, who developed the system at its technical lab in Birlinghoven, Germany, with partners Frenzel-Bau and Bayer MaterialScience AG. "We have now broken new ground in track technology," claimed Hennecke, in a 20 July statement. The aim of this Durflex foam injection, is to "completely fill the hollow spaces within the ballast," with foam, according to Hennecke. This will prevent the ballast from moving whenever trains cross the rails. As well as reducing noise emission, Durflex also cuts operating and lifecycle costs, as it prolongs the service life of the tracks considerably. Using Durflex eliminates ballast repacking and reduces track deformation. In turn fewer rails and sleepers get broken and "network availability rises notably," said Hennecke. Hennecke GmbH and partners carried out initial tests to develop the right raw material and injection parameters for this novel use. Following this, Hennecke installed a specially designed high-pressure metering machine (Topline HK650) in a Deutsche Bahn train. This used a triple-deviation mixhead (MX type) to inject the metered mixture. The machine and the Bayflex raw material system were optimised using an online batch process for mixing of time-critical components.After final tests at a siding of the Bonn-Beuel station, on a rail system specially built for this purpose, the team presented its results to Armin Keppel, president of the Federal Railway Authority, Bonn mayor Bärbel Dieckmann, and the press. "