Track measuring car
Track measuring car (or G slightest m ess t railcars, short GMT ) are web service vehicles , which serve to detect the track geometry. Initially, mostly old passenger coaches were prepared for this purpose, which were moved by locomotives . Newer track measuring cars are often self-propelled and are specially built for this purpose.
By the 1920s, traffic on busy railroad lines had reached a density that made visual and manual inspections of the track systems inadequate. In addition, the planned maintenance breaks became shorter and shorter and the higher speeds required a more precise track position.
The early development of the track measuring cars went as follows:
- 1925 The Chemins de fer de l'Est (EST) temporarily installs an acceleration recorder developed by Emile Hallade in a car, with which the movements of the measuring car resulting from track position errors are recorded. Cross and vertical movements as well as rolling movements can be recorded.
- 1927 The Atchison, Topeka and Santa Fe Railway (ATSF) occupies built by Baldwin test vans in operation, with a gyroscope of Sperry Corporation is equipped.
- 1929 A vehicle similar to the one supplied for the ATSF goes into operation at Estrada de Ferro Central do Brasil . The Deutsche Reichsbahn builds a measuring car with a gyroscope from Anschütz from Kiel in its own workshops . In the mid-1930s, the Reichsbahn put additional measuring cars based on the Reichsbahn-Anschütz system into operation. The Great Indian Peninsula Railway (GIPR) puts a combined measuring car for traction technology and track measurement into operation.
- 1930 The SBB builds measuring devices manufactured by Amsler in Schaffhausen to record the quality of the track position in an existing traction measuring vehicle.
- 1933 The Chemin de fer de Paris à Orléans (PO) builds a makeshift measuring vehicle under the direction of André Mauzin , who developed the measuring devices himself
- 1936 The Compagnie des chemins de fer de Paris à Lyon et à la Méditerranée (PLM) builds a measuring vehicle with Mauzin devices, which are built by the French Westinghouse Electric .
- 1939 Ferrovie dello Stato Italiane (FS) puts a measuring vehicle with Amsler devices into operation.
While the first measuring cars with acceleration recorders worked, measuring bogies or feeler rollers were also used for track position detection from the 1960s. Newer vehicles are mostly self-driving and use the light section method to precisely record the superstructure.
Recorded measured variables
The exact measurement of the track geometry is particularly important in high-speed traffic in order to ensure the safety of rail operations, because there is only a small margin for deviations.
Usually the following is measured on the track:
- Radius of arcs
- Vertical position of the left and right rails
- Wear of the rail profiles
Various track measuring vehicles are used at DB Netz . Originally, the tracks were checked mainly with converted rail buses such as the 725 and 726 series vehicles . However, as time progressed and the permissible speeds increased, more modern and more precise track measuring cars were required. In 1975, the Deutsche Bundesbahn ordered a track measuring train from MBB, classified as the 719 series and sometimes referred to as the Eisenbahnprüf-Express , which was followed in 1996 by a further unit, ordered from Plasser & Theurer , which allows a test speed of 70 km / h. The two last-mentioned trains use ultrasound and eddy currents to examine the rails for material defects or damage from wear and tear and material fatigue.
Regular trips to check the track geometry are now also carried out by two RAILab sets. These are two converted interregional cars that are equipped with modern laser technology and can determine positions with millimeter accuracy with the aid of an inertial system. Private providers also have measuring vehicles, one example being Eurailscout .
The Swiss Federal Railways use a track measuring car manufactured by the Swiss company MATISA for the annual inspection of the rail network. The track measuring car has the registration number X 60 85 99-73 105-6, weighs 45 tons and has a bogie distance of 15,000 mm, its length over buffers is 19,900 mm. A two-axle measuring chassis is attached in the middle of the car for the measurements.
The ÖBB also use track measuring vehicles. While after the end of World War II yet the former saloon car of Adolf Hitler was rebuilt and used as track recording vehicle, so now mostly converted are UIC cars in use.
The Wiener Linien since 2003 are two measuring carriage during operation. One system has a conventional structure (Imagemap) and is used in the subway area. Another system was developed on the basis of a previous control vehicle ( DUEWAG system ) for the grooved rail tracks of the tram .
The measurements for the vehicles of Wiener Linien are based on the so-called base point and light section method . With the former, the unworn foot of the Vignole rail is used as the basis for the measurements. The radius of curvature from the transition of the foot to the bridge serves as the basis for the measurements; the calculated center point as a reference point for the superimposition of the unworn profile. With the light section method , the rail is irradiated by 2 (grooved rail 3 each) lasers and an outline image is generated. This is then filmed by highly sensitive line scan cameras and converted into two-dimensional images in a geometry unit of the on-board computer. The geometry and wear values of the track or rail are determined on the basis of these images . The geometry can be measured every 25 cm, a rail profile every 50 cm. The measuring speed is in principle not limited and is around 15 km / h underground.
- Jürgen Janicki, Horst Reinhard: Rail vehicle technology. Bahn Fachverlag 2008, ISBN 3-980-80025-3 .