Rail fault

A rail fault is the term used to describe damage to railroad tracks . The UIC categorizes these in a rail fault catalog in order to ensure international comparability.

Rail defects include manufacturing and welding defects as well as rolling contact fatigue defects . Corrugations, on the other hand, are created by converting the material to martensite in the so-called white etching layers .

Head checks

Driving edge cracks on the rail of a high-speed line

Head checks are fine surface cracks that occur at a distance of 2–7 mm that occur at a 45 ° angle to the direction of travel. They usually arise on the running edge of the outer rail in curves with radii of 400–1500 m, which is also known as gauge corner cracking ( GCC for short ). Head checks are caused by rolling contact fatigue. The cracks are treated with the grinding carriage . Head checks that have not been treated grow into the interior of the splint, where the cracks can unite, so that larger material breaks can occur.

Squats

Squat on the rail head

Squats are indentations on the head of the rail, which are initially visible as small, black dots, but then enlarge and develop into a semicircular or V-shaped crack, with the opening of the shape facing the running edge. They occur due to rolling contact fatigue in the straight track of high-speed lines or in places where large tractive forces are transmitted.

After the increased occurrence of squats, the Danish infrastructure operator Banedanmark initiated a research project in 2010 to investigate the diverse combination of causes that lead to the formation of squats.

Impressions

Impressions are caused by foreign bodies rolling over. Irregular impressions are called brown spots . In ore railways , indentations occur primarily in the area of ​​the loading facilities , where pellets that have fallen onto the rails are rolled over. The IORE locomotives of the Swedish ore railway are therefore equipped with rail brushes to remove the pellets .

Slip waves

Slip wave

Waves or short waves are periodic surface irregularities with lengths of 5 to 30 cm and a depth of 0.1-1 mm. They are generated by the drilling slip of the wheels on the inside of the curve in narrow track curves with a radius of less than 800 m.

Corrugation

Corrugation due to the slip on the inner rail in the curve of a standard gauge track

→ Main article : Corrugation

Corrugations are quasi-periodic unevenness of the driving surface in straight tracks and track curves of larger radii with wavelengths of about 2 to 10 cm and depths of 0.01 to 0.4 mm. Up to now, they have mainly been represented in the literature as brightly shining mountains with solidified surface layers and dark valleys with corrosion scars and deformed surface layers.

Belgrospis

Belgrospis are periodic crack nests on the driving edge that have been observed in connection with corrugation on high-speed routes . This type of rail fault occurs on the outer rail in curves, as well as in straight sections alternately on the left and right running edge. They are caused by rolling contact fatigue.

Slingshot points

Skid marks occur when driven axles skid when starting up . The resulting heat transforms the pearlite in the steel into martensite .

Transverse defect

Lateral defects are cracks that run perpendicular to the direction of travel. If they expand sufficiently, they can lead to a rail breakage and are therefore very dangerous if they are not detected.

Broken rail

Rail breakage due to a fault caused by lateral snow pressure

A broken rail is the complete failure of the rail so that the route can no longer be used. There are different types of broken rails:

• Horizontal rail breaks run parallel to the direction of travel in the web and separate the rail head from the rail foot.
• Vertical broken rails run across the direction of travel through the entire rail profile. They are visible as a line on the rail head when they are created.
• Kidney hernias run a few centimeters lengthways in the bar and then change their direction towards the rail foot. The name comes from the shape of the broken piece.

Rails can break for various reasons, for example due to the stresses caused by unusual temperature fluctuations, welding defects or manufacturing defects such as voids caused by gas bubbles in the steel. If the rails are embedded in a slab track , they are exposed to particularly high loads.

literature

• Karl-Otto Edel (Ed.): Conference report. International symposium "Rail Defects" . Brandenburg an der Havel, November 16 and 17, 2000. Interdisciplinary research network for railway technology and technology. a., Berlin a. a. 2000.
• Wolfgang Schöch: Rolling Contact Fatigue - An Overview of a Worldwide Phenomenon
• Kim Sarah Pollak: Life Cycle Cost using the example of running rails in highly stressed areas of the Hamburger Hochbahn , Section 3.3 Rail faults

Individual evidence

1. ↑ Carsten Rasmussen, Bo Nielsen, Lukas Prettner, Stephan Scheriau, Albert Jörg, Wolfgang Schöch, Richard Stock: Tracking down the origin of squats . In: Railway Gazette International . tape 172 , no. 1 , 2016, ISSN  0373-5346 , p. 39-43 .
2. ^ Matthias Müller: Broken rails. (No longer available online.) In: Gleisbau-Welt. Archived from the original on April 14, 2016 ; Retrieved April 10, 2016 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  
3. ^ Peter Neumann: S-Bahn chaos in Berlin. Three broken rails on a newly renovated S-Bahn line. Berliner Zeitung from November 19, 2014.
4. ↑ Frost leads to broken rails near Oldenburg. In: www.bild.de. Retrieved April 10, 2016 .