Track warpage

Track fault in Gütersloh on the Teutoburg Forest Railway

A slight track warpage marked as a speed limit.

Tram track over a bridge in Augsburg .

A track warpage is an unintentional deformation of railroad or tram tracks, which no longer allows safe use of the affected track . Track warping is usually caused by thermal elongation of the rails in the summer heat .

In the past, longitudinal expansion was absorbed by expansion joints. Today, railroad tracks are designed in such a way that the thermal forces that would cause the rails to expand when exposed to heat are absorbed by the superstructure , i.e. the sleepers and the track bed , so that the rails do not expand. If the superstructure can no longer absorb these forces, for example due to poor laying, poor maintenance or extreme heat, the rails nevertheless expand in rare cases, so that the track is deformed and forms serpentine lines. If such a track warpage is not discovered in good time, it can lead to an accident, for example due to derailment. A track warpage can develop immediately at the moment of driving, since additional dynamic forces from the rail vehicle can act on an already heavily loaded track.

At the Austrian Federal Railways (ÖBB), rails were painted white as a test during the heat waves in Europe in 2019 .

In addition, frost uplifts also cause distortions when the sleepers are moved - this is counteracted by a technically properly constructed track bed . Any other loosening of the sleepers is prevented by neatly compacting the sharp-edged track ballast . Other causes are various small-scale movements of the subsoil , erosion due to flood or groundwater, ingrown roots due to trees that are too close, and much more.

In the case of old, unkempt stretches, this can lead to considerable vertical and lateral distortions. Since the rails are fixed to each other on the sleeper, track errors that lead to direct derailment only occur when several sleepers in one area have been destroyed. Until then, the route will mostly remain passable slowly.

literature

• Köstermann, Sladek, Meißner: Manual of the rail technology. Materials, manufacture and processing, quality assurance . Ed .: DVS. DVS Media, ISBN 3-87155-218-6 , p. 184 .

Individual evidence

1. ↑ Juliane Pamme: Cool rails - ÖBB color rails against heat white. In: presse.oebb.at. July 20, 2019, accessed July 27, 2019 .