Germany's new high-speed Cologne to Frankfurt line will use concrete trackbed throughout its entire length.
Several different designs are being tried. A pilot project last August demonstrated the benefits of the slipformed Rheda trough trackbed system placed using wire-free guidance to control a Wirtgen SP500 paver.
The pilot was a tough test for the paver. Some 1.3km of twin trackbeds had to be placed on to the existing hydraulically bound base course, which meant that in most cases the machine had to operate with one pair of tracks on the base course and the opposite pair trying to get a grip on the unbound crushed stone forming the embankment.
To make matters worse, the trackbed had to be laid with a crossfall of up to 12%. Main contractor Dywidag used two Leica total stations linked by radio modem to the slipformer's onboard computer to ensure the required accuracy. Placing rates averaged 1m/min.
So successful were the trials that the Dywidag-Rheda system has since been specified for a 10km stretch of twin track, where it will be placed on a concrete base course. Four Wirtgen SP 500s will be used for this contract.