Trials have been carried out by München University with a novel design of embedded rail system developed by Balfour Beatty Rail Projects. An initial batch of rail has been rolled, but a firm commitment to full-scale field trials has yet to be signed.
The Type 14072 rail weighs 74 kg/m and has the same surface profile as UIC60. There the resemblance ends, as the rail cross-section displays no web or foot (Fig 1). The symmetrical rail is embedded in a U-shaped elastomeric pad and an FRP shell located in a low-profile reinforced concrete track slab. Seals on each side of the rail prevent moisture and debris from penetrating the area between rail and slab. The pad and seals are resistant to greases and acids and are designed for a 30-year life.
The slab can be laid using a slip-form paving machine, providing the recesses needed for the embedded rail subsystem and other items such as balises or axle-counters. Rail is supplied in long lengths from the mill or in shorter lengths for on-site welding. The rail, pad and shell are held by special alignment frames and then grouted into position.
Balfour Beatty says that the design can handle 30 tonne axleloads and is suitable for up to 330 km/h. Up to 6mm of side wear and 2·5mm of head wear can be accommodated. Gauge widening is limited to a maximum of 2mm.
The trials suggest that the system has good static and dynamic spring characteristics, and performance after four million load cycles indicated that the pad had not deteriorated.
Continuous embedded support limits transverse and longitudinal rail movement under load, and Balfour Beatty says that a broken rail is ’completely retained by the system, with traffic still able to pass until a repair can be effected’. The slab outside the rails is designed to form a rigid derailment guard. The continuous slab can be cleaned mechanically, and is free of obstacles for staff walking on the track, or for emergency access.
There are no conventional fastenings, so reducing the costs of inspection and maintenance.
Balfour Beatty Rail Projects, Great Britain
Reader Enquiry Number 140
CAPTION: Fig 1. The rail has the same surface profile as UIC60, but does not have a web or foot
CAPTION: Fig 2. The rail is embedded within the low-profile reinforced concrete track slab, with seals to keep out moisture and debris