Rail extension

Rail extension device on a tram bridge

The rail extension or the rail extension device is a component of the track superstructure that allows greater longitudinal rail movements.

When the rails are pulled out, the rails are separated into a stock rail and a tongue rail on the inside. The rails are positively connected to one another in the overlapping area by supporting jaws. Depending on the design, the tongue or the stock rail can be moved lengthways and can slide.

Rail extensions are mainly installed as a transition structure in larger bridges in the area of the expansion joint, in order not to obtain inadmissibly large constraining forces in the rail from the longitudinal deformation of the bridge structure. The changes in length are primarily caused by thermal expansion, but also by dynamic loads on the bridge (such as braking and starting a train).

According to the permanent way of construction guidelines of Deutsche Bahn , rail extensions from a structure length of more than 90 meters must be installed for concrete or composite bridges that are longitudinally fixed on one side, and for steel bridges from 60 meters in length. When installing a Meyer / Wunstorf control rod system that moves the fictitious anchor point in the middle of the bridge, a rail extension is only required for steel bridges from a length of 120 meters.

The construction for an extension path of 700 millimeters is referred to as "SA-830" and can be used for steel bridges up to 500 meters and for prestressed concrete bridges up to 700 meters in length.

Picture gallery

Rheinbrücke Hemishofen , rail expansion and catch rails
Rail extension on a railway bridge with LZB line conductor
Display for the change in length on a railway bridge
Slab track on the Oelztalbrücke with compensating plate and rail expansion

Web links

Commons : Expansion joints (rail track) - Collection of images, videos and audio files

Individual evidence

^ Rolf H. Pfeifer, Tristan M. Mölter: Handbuch Eisenbahnbrücken . DVV Media Group, Hamburg 2008, ISBN 978-3-7771-0378-5 , p. 267
↑ Hartmut Meyer, Ralf Schubart: The control rod system Meyer / Wunstorf - mode of operation and experiences . Stahlbau 57 (1998), No. 8, pp. 686-692
^ Rolf H. Pfeifer, Tristan M. Mölter: Handbuch Eisenbahnbrücken . DVV Media Group, Hamburg 2008, ISBN 978-3-7771-0378-5 , p. 78

[1] Rolf H. Pfeifer, Tristan M. Mölter: Handbuch Eisenbahnbrücken . DVV Media Group, Hamburg 2008, ISBN 978-3-7771-0378-5 , p. 267

[2] Hartmut Meyer, Ralf Schubart: The control rod system Meyer / Wunstorf - mode of operation and experiences . Stahlbau 57 (1998), No. 8, pp. 686-692

[3] Rolf H. Pfeifer, Tristan M. Mölter: Handbuch Eisenbahnbrücken . DVV Media Group, Hamburg 2008, ISBN 978-3-7771-0378-5 , p. 78