track
As a track or tracks (in Switzerland and South Tyrol), the road is for rail vehicles referred. It forms the basis for rail traffic . The track usually consists of parallel transverse sleepers on which two parallel steel rails are attached. Depending on the volume of traffic, railway lines can be laid out with one or more tracks.
Track in connection with a number or a number is usually used in German train stations to clearly identify individual platform edges, which are indicated in the train timetables or on display boards as the arrival or departure point of a train.
Word origin
Gleis und Geleis (plural: Gleise und Geleise ) have their word origins in the 14th century in late Middle High German Gleis, a wheel track or a trodden path. It is a collective formation of the Middle High German leis or leise für Spur. This in turn goes back to the Old High German leisa , in connection with wagons as waganleisa, i.e. wagon track. Originally, it was used to describe the parallel ruts impressed in the ground by single-axle carts (including ox carts ) or two-axle wagons ( horse-drawn carts ). In Roman road construction - and then again from the Middle Ages - one knew the tracks carved into the rock, which enabled the vehicles to drive safely on the exposed path, especially in the mountains. These cart tracks required an at least regionally standardized track width for the wagons. Occasionally, turnout-like branches occurred in ancient streets.
Track has not been used in German railway terminology for over a hundred years. The word form is considered “elevated” in German usage and is still common in standard language in Austria and Switzerland: In Austrian German , however, the word form is considered obsolete, in Swiss Standard German it is a subsidiary form.
construction
The sleepers made of wood , steel or concrete with special fastening elements keep the rails at the intended, continuously constant distance - the so-called track width - from one another. The sleepers are in the bedding , which is mostly made of gravel . This type of construction is known as a "ballasted track". Their advantage is the good adjustability, easy adaptability to changes and the natural elasticity. However, elasticity and positional security are only guaranteed if the substructure is stable and the gravel is clean and permeable to water. Both require a certain and regular maintenance effort. In the past, gravel bedding was also used on low-traffic branch lines. This is cheaper, but the positional stability and load-bearing capacity are significantly lower than the ballasted track.
Another design is the so-called slab track , in which sleepers or other rail fastening supports are integrated in a superstructure plate made of concrete or asphalt . This is used in Germany on high-speed and high-speed lines. The positional security and stability is significantly better than with the ballasted superstructure, but the solid track is hardly elastic, which must be compensated for by more complex rail supports and fastenings. In addition, changes that were not prepared during construction are much more complicated.
There are also roadways in which the rails are attached directly to a stable, flat substructure with screws or clamp springs without sleepers. This type of superstructure is called “direct support”.
There is also the cross-sleeper track variant (KLS). Here the sleepers are arranged along the axis of the track.
The rails form the track, they are steel profiles that were initially screwed together with brackets, but in more modern designs are completely welded. For railways are nowadays generally flat bottom rails used in particular for layd tram tracks and grooved rails . The wheels of the railway vehicles run on the rails . Slipping off the track is prevented when driving by the flange and sinusoidal running of the wheelsets . The wheel flanges ensure the guidance of the wheels in switches and crossings .
The entirety of rails, iron bars, sleepers and bedding is called the superstructure . Dams , incisions and cuttings as well as bridges are part of the substructure of the tracks, with which the unevenness of the terrain is leveled. The upper and lower structure together are called the track body .
The track absorbs the weight and other loads that the rail vehicles exert on the rails. The maximum speed of a route and the maximum permissible axle load of the vehicles depend on the superstructure as well as the substructure .
Track construction and construction
The project planning and laying of tracks including the superstructure and substructure as well as their maintenance and care are referred to as track construction. Special track laying machines are usually used for this.
Consideration of inclines and slopes
Due to the landscape and geological conditions, it may be necessary to lay and secure the tracks with appropriate inclines or slopes. See also adhesive membrane .
Consideration of temperature and geological changes
New rails are rolled by the manufacturer in standard lengths of 30, 45, 60, 120 or 180 meters. When the rails are installed in the track structure, the rails are then either lashed into a so-called joint gap track or into one seamless track welded.
In the case of the joint gap track, the ends of two rails with a certain temperature-dependent laying gap at the so-called rail joint are put together and screwed together using straps. At laying temperatures of more than 20 ° C (for 60 meter rails) no laying gap is created, at less than 20 ° C a gap of up to 19 millimeters. At temperatures of more than 20 ° C, the gap between the rails disappears and temperature stresses also occur in the joint gap track.
In accordance with the Deutsche Bahn AG superstructure regulations (DS 820), butt gap tracks are only used on surfaces that are at risk of slipping or that are unevenly yielding, for example in areas with damage from the mountains .
In all other cases, a seamless track, also known as a continuously welded track, is used. Here, the ends of two rails are welded together without leaving a gap. In order to keep mechanical stresses due to temperature fluctuations within manageable limits, rails are welded in the area of the Deutsche Bahn AG in a temperature range of 20 to 26 ° C. The mechanical stresses are almost balanced within this temperature range.
At higher or lower temperatures, however, due to the expansion or shrinkage of the rails in the longitudinal direction, mechanical stresses occur in the track, so-called “longitudinal displacements”. So z. B. Both in a gap track as well as in a gapless track at rail temperatures of 60 ° C (which are also quite possible in Central Europe in summer) compressive forces of around 1500 kN (with UIC-60 rails).
However, these mechanical tensions are not compensated for by the rail joints in the case of gap tracks or by compensating devices in the case of seamless tracks (except in extreme conditions or on bridges, see below). Rather, the compressive forces remain in place in the track. The rails do not move horizontally. Due to the bracing of the rails with the sleepers, the large frictional forces between the rail base and the rail fastening as well as the ballasting or pouring into concrete, the compressive forces are transmitted directly into the subsurface. In particular, the ballast arranged laterally next to the sleepers must have a certain minimum width so that the track remains in its position and the pressure forces can be reliably diverted. In addition, the underside of the sleepers for ballasted superstructures is particularly rough in order to increase the friction between the ballast and the underside of the sleeper.
Color treatment
In the entire network of the Italian state railways FS, rails are painted white to prevent warping caused by high temperatures. The temperature decrease is 7–10 ° C.
In Switzerland, rails were also dyed white on a test basis at the Rhaetian Railway in 2018 .
The Austrian Federal Railways ( ÖBB) also started an infrastructure project in Bludenz in 2019 to combat the distortions caused by rising summer temperatures.
Rail extensions
Rail extensions are installed for particularly large temperature differences, operational longitudinal forces such as braking or accelerating vehicles and on long concrete and steel bridges. Here, a stock rail and a tongue slide against each other in the longitudinal direction, whereby the extension lengths can be between 200 and 830 mm.
Track position error
A track position error is an error in the position of a railroad track in the horizontal or vertical direction or in the mutual height of both rails, which can arise during construction, operational influences or changes in the subsoil.
Guide rail
- for targeted guidance of railway vehicles according to the derailment are many narrow - in particular under bridges and guide rails mounted. These usually consist of conventional Vignole rails so that the track looks like a four-rail track. The guide rails are installed at least 10 meters in front of and behind the structure to be protected and designed as a safety device.
Protective rail
Another possibility is the use of protective rails, which are particularly used in arches. These are special profiles that are attached at a distance of about 80 mm from the inner rail. Normally, the protective rail is not touched by the wheel flange, but the choice of the distance prevents the flange from climbing on the outer rail.
In even tighter arcs, mostly on trams, guardrails relieve the outer rails, since the inside of the flange is against the guardrail on the inner rail. This reduces the risk of derailment .
Branches and crossings
Branches of tracks are realized with railway switches. Another important design element is the intersection . If one track separates from the other and one runs over the other, this crossing point is referred to as a flyover structure .
Multi-rail tracks
A three- rail track has three rails laid side by side to enable vehicles of different gauge to be driven on, with one of the outer rails being used by vehicles of both gauges. Three-rail tracks are used in train stations where trains with different gauges meet, but also on the factory premises of vehicle manufacturers or during the conversion phase of a railway to a different gauge (e.g. on the Stuttgart trams until December 2007). Longer three-rail track sections exist in Australia , for example .
Because of the shared rail, special individual switches are required for threading in and out, especially when there are only minor differences between the two gauges and large arc radii or when rail and tram vehicles with narrower wheel tires are operated in a mixed manner because of the otherwise too small contact surface of the running wheels. Otherwise, as is the case with the Saxon narrow-gauge railways, for example, wheel guides are sufficient, which are also installed on the outside in the area of the break in the running edge to reduce the necessary groove width. A special form of a switch is the so-called track track distortion , in which, despite different types of vehicles with different car body widths, easier entry and exit is to be achieved. The vehicles with the narrower car body can be moved to the edge of the platform. Before or after the stop, all vehicles use the common main track.
Are both gauges too similar, e.g. B. meter and cape gauge or standard and Russian broad gauge, a three-rail track with standard material is no longer possible because the difference between the two tracks is less than the width of a rail including the fastening elements. In this case, four rails in the form of a track loop are required for a common track ( four-rail track ), whereby the individual track axes do not overlap. With four rails, three gauges can be accommodated on one track, e.g. B. standard, cape and meter gauge, which could be necessary in some parts of Africa in the future.
The formerly sharing the route Bad Ischl - Bad Ischl freight station by the narrow gauge of SKGLB Museum and the standard gauge of Salzkammergutbahn led to a - unique in Austria - asymmetric four-rail track: A track of the narrow-gauge railway was laid inside the standard gauge rails, the other outside.
Four-rail tracks can also be designed so that the track axes of both gauges coincide. This requires a sufficiently large difference in track widths and has the advantage that no lateral expansion of the clearance profile is required due to the lateral shift. This is particularly important when standard gauge wagons jacked up on the narrow-gauge track are transported by means of roller stands or trolleys . At the same time, the common track axis simplifies the regulation of a catenary that can be used for both gauges . Even in narrow tunnels, a further special center track may be necessary despite two existing standard gauge tracks, if the route is also to be used for oversized vehicles with excess loading dimensions .
Another advantage of the four-rail track compared to the three-rail track is that, even with different wheel set dimensions, no switch devices are required to bring the gauges together (potential sources of accidents!); one loop of the track is sufficient . This can also be useful if there is only one track width, for example in front of narrow bridges or bottlenecks in a tram network (e.g. station platform).
Sechsschienige Ausfädelungen necessary if, in addition to a single-track railway tram vehicles in equipment design will operate and therefore platforms are needed on both sides. With the help of such a threading out, such. B. on the Lossetalbahn from Kassel via Kaufungen to Hessisch Lichtenau , the tram trains can be brought to the platform edge on the right in the direction of travel. Long-distance railway vehicles run in the middle without crossing the platforms. If all platforms are on the same side, four rails are enough.
In order to achieve a particularly wide overall rail width for particularly tall vehicles, four -rail tracks are sometimes set up as a pair of two (approximately) standard-gauge tracks that are far apart . Accordingly, the vehicles stand on chassis of normal track width lying next to one another in pairs. So there is no need for extra-long wheel axles. Examples are:
- Brighton and Rottingdean Seashore Electric Railway (1896–1901), England, pairs of tracks with 828 mm gauge and 5486 mm "total gauge".
- Very Large Array , Socorro, New Mexico, USA for positioning radio telescopes . Estimated standard gauge tracks with 7 m track center distance, so 8.5 m "total track".
See also
- Three-rail tracks in Norway
- The list of narrow-gauge railways in Switzerland and the list of former Swiss railway lines contain all existing and former Swiss railways with three and four-rail tracks.
- Perambulator operation # Three-rail system
Rack tracks
In the tracks of rack railways there is usually a rack in the middle of the track , in which the drive gears of the traction vehicles and the brake gears of the other vehicles engage. There are different types of racks with the teeth on the top (Abt and Strub systems), on the sides (Locher system) and with a ladder rack (Riggenbach system).
Terms in German-speaking countries
In Germany and Austria, a distinction is made between main and secondary tracks . Main tracks are tracks that train journeys can use as scheduled. All other tracks are referred to as siding . The main tracks and their continuation in the station are called continuous main tracks .
In Switzerland, this refers main track on a track in which a signally (not with shunting signals) secured Zugfahrstraße can be adjusted.
Track maintenance
The tracks have been and are in some cases still checked by a route attendant , primarily for defective rail fastenings. He carries the appropriate wrench with him and adjusts his step width to the threshold distance of often 65 cm so that he does not step on the uneven, coarse gravel. In order to prevent the track area from becoming weed, the vegetation is regularly checked to this day , that is, herbicides are applied to the track area by special blasting trains .
Historical review
In the first half of the 19th century, four types of track were distinguished according to the material used:
- English rails: today's iron rails, expensive but permanent, laid on stone blocks or wooden sleepers, soon replaced the American construction method for railways.
- American rails: wooden rails with metal fittings, cheap to build but costly to maintain, were laid on wooden sleepers. Were also used on horse-drawn railways (e.g. Budweis – Linz).
- Wooden rails: rails carved from tree trunks, in use especially in mines since the Middle Ages.
- Stone rails: Stone rails on a stone base, were mainly used on test tracks in France.
Gauges and track geometry
The gauge is an essential feature of the track geometry . examples are
literature
- O. Estorff, M. Firuziaan: Simulation of the Dynamic Behavior of Bedding-Foundation-Soil in the Time Domain . Springer Verlag, 2002.
- Erich Ensinger: The track construction (guide for railway workers) . 3rd edition GdED Verlagsgesellschaft, Frankfurt a. M. 1962 (219 pp.).
- August Haarmann: The Railway Track. Historical part . Engelmann, Leipzig 1891 (XL, 852 p., With numerous illustrations - the standard work on the subject).
- August Haarmann: The railway track. Critical part . Engelmann, Leipzig 1902 (277 p., With numerous illustrations - the standard work on the subject).
- Robert Hanker: Railway superstructure . The basics of track construction . Springer, Vienna 1952 (VIII, 256 p., With 258 text fig. 8 °).
- Klaus Knothe: Track dynamics (civil engineering practice) . Ernst, Berlin 2001, ISBN 3-433-01760-3 (VIII, 221 pp., Ill., Graph. Darst. 24 cm - Bibliography, pp. 187-214).
- Bernhard Lichtberger: Track manual. Substructure, superstructure, maintenance, profitability . 2nd edition Tetzlaff, Hamburg 2004, ISBN 3-87814-804-6 .
- Wolfgang Schiemann: Rail traffic technology: Basics of track alignment . Teubner, Stuttgart / Leipzig / Wiesbaden 2002, ISBN 3-519-00363-5 (334 pp., Graphic representation).
- Volker Matthews: Railway construction . 4th edition Teubner, Stuttgart / Leipzig 1998, ISBN 3-519-30113-X (284 pages, 55 tables).
- Fritz Fastenrath (ed.): The railroad track . Ernst & Sohn, Berlin 1977, ISBN 3-433-00783-7 (437 pages, with numerous illustrations).
- Heinz E. Deckart: Production of seamless tracks and switches . In: Heinrich Köstermann, Klaus Meißner, Herbert Sladek (eds.): Manual of rail technology . DVS Media, Düsseldorf 2008, ISBN 978-3-87155-218-2 (= welding technology series , volume 152).
- Karl Derlin: Uninterrupted tracks and switches. Production and importance of continuously welded tracks and points . Dr.-Arthur-Tetzlaff-Verlag, Frankfurt (Main) and Berlin 1960 (55 p., 16 fig., 6 tables).
- John Wattmann: Longitudinal forces in the railroad track . 2nd edition Otto Elsner Verlagsgesellschaft, Darmstadt 1957 (234 pages, numerous illustrations, tables and formulas, bibliography).
Web links
Individual evidence
- ↑ Geleise in spelling, Ed. Duden- Verlag. See also: Gleis in Wiktionary .
- ^ Geleise in Duden-Online, Ed. Duden-Verlag.
- ↑ See Austrian Dictionary , 41st edition, ÖBV , Vienna 2009, p. 258.
- ↑ See German orthography. Duden Volume 1, 25th edition, Duden-Verlag, Mannheim 2009, p. 475.
- ↑ The mobility manager https://www.dmm.travel/nc/news/zuege-auf-weissen-schienen/
- ↑ ÖBB press release https://presse.oebb.at/de/presseinformationen/coole-schienen-oebb-faorben-schienen-gegen-hitze-weiss-ein
- ↑ Satellite View Very Large Array google.com/maps, accessed July 12, 2020.