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The track spacing is the distance between the track centres of double-track railway lines. There are standard distances derived from the standard loading gauge in a country. For high-speed trains and in tighter curves that distance needs to be increased.
The track spacing is also called the centre-to-centre spacing to differentiate it from the edge-to-centre spacing of a railway. These two values may be different depending on how signal masts are added to the overall track geometry.
The distance between the track centres makes a difference in cost and performance of a double-track line. The track centres can be as narrow and as cheap as possible, but maintenance must be done on the side. Signals for bi-directional working cannot be mounted between the tracks so must be mounted on the 'wrong' side of the line or on expensive signal bridges. Track centres are usually wider on high-speed lines, as pressure waves knock each other as high-speed trains pass.
The minimum track spacing can be derived from the loading gauge. The European Berne Gauge has a width of 3,150 mm (10 ft 4 in). The minimal distance to structures on the side of the track is half of it but that is doubled again for double track lines. As the wagon can move within the rail gauge one adds 100 mm (3.9 in) and with a possible displacement of tracks over time one adds some 250 mm (9.8 in) as a security margin. This leads to a minimum centre-to-centre spacing of 3,500 mm (11 ft 6 in). In fact, the first Prussian railways were built to that standard but it soon became apparent that it was too dangerous with some passengers having a hand or their head out of the window.
Narrow track centres might be 4 metres (13 ft) or less. Narrow track centres may have to be widened on sharp curves to allow for long rail vehicles following the arc of the curve, and this increases a surveyor's workload. Widening a track centre to 5 m (16 ft) or so suits high-speed trains passing each other, and eliminates the need to widen the centres on sharp curves. Increasing width of track centres of 6 m (20 ft) or more makes it much easier to mount signals and overhead wiring structures.
In the United Kingdom, the early lines of the Great Western Railway were built to Brunel's broad gauge, which was also associated with a more generous loading gauge. This is still apparent along those lines which remain in use today: structures such as bridges and tunnels are larger, and the distances between opposite platform faces are larger.
Very wide centres at major bridges can have military value. It also makes it harder for rogue ships and barges knocking out both bridges in the same accident.
Railway lines in desert areas affected by sand dunes are sometimes built on alternate routes so that if one is covered by sand, the other(s) are still serviceable.
If the standard track centre is changed, it can take a very long time for most or all tracks to be brought into line.
The general standard in Germany and Switzerland had been to build new tracks with a centre-to-centre spacing of 3.8 m (12 ft) and a spacing of 4.5 m (15 ft) in railway stations. Depending on the usage of the tracks it was still possible to build new double track lines with track centres of just 3.5 m (11 ft). With the trains going faster over time, the track centres were increased to 4 m (13 ft) on main lines.
The advent of high-speed trains required a stronger regulation which was regulated in Germany's EBO. The first update of 1982 increased the minimum track centre to 4 m (13 ft) allowing no more exceptions. But by 1991 it was replaced with a table taking into account the maximum speed of the trains on a track as well as the curvature. A distance of 4 m (13 ft) was considered enough for speeds up to 200 km/h. At 250 km/h the tracks have a centre-to-centre distance of 4.5 m (15 ft) (while the first tracks in the 1980s were built with a distance of 4.7 m (15 ft)).
The TGV track construction puts both rail tracks into a common concrete block, so they can disregard a safety margin for track displacement. This allows high-speed rail to have a centre-to-centre distance of just 4.2 m (14 ft). Additionally, these lines are only allowed for high-speed passenger rail where no out-of-gauge loads are expected and the windows in the trains can not be opened.
In Japan, the first high-speed tracks of the Central Japan Railway Company Shinkansen were built with a distance between track centres of 4.3 m (14 ft). [1]
The largest minimum track centre is planned for Indias high-speed network requiring a common distance of 5.3 m (17 ft).
Track spacing distance | Example |
---|---|
9 ft 8 in (2.95 m) | Liverpool and Manchester Railway 1830 at opening day; later widened. |
10 ft 8.5 in (3.26 m) | United Kingdom (standard gauge plus 6 ft) |
11 ft 0 in (3.35 m) | New South Wales 1855 old standard (estimated) |
12 ft 0 in (3.66 m) | New South Wales 1910 new standard for 10 ft 6 in (3.20 m) wide carriages. Rounded in imperial. |
13 ft 1.5 in (4.00 m) | New South Wales 1973 metric standard; rounded in metric. |
13 ft 9 in (4.20 m) | LGV Rhône-Alpes |
13 ft 11 in (4.23 m) | Tōkaidō Shinkansen |
14 ft 1 in (4.30 m) | San'yō Shinkansen |
14 ft 9 in (4.50 m) | New South Wales Certain ARTC lines after about 2012. [2] |
14 ft 9 in (4.50 m) | Erfurt–Leipzig/Halle high-speed railway |
15 ft 5 in (4.70 m) | Nuremberg–Erfurt high-speed railway (before 1998) |
By definition, the track spacing is given from centre to centre of a rail track. For an actual construction the distance is measured from the inside of a rail head to the matching one of the other track. As far as both tracks have the same gauge this is the same distance.
Track centre may need to be widened on sharp curves. [3] Gauge may also need to be widened, requiring special sleepers if made of concrete.
If track centres are "narrow" then a problem on one track may affect other track(s). This is called a "common mode" failure. It affects rail, road, and canals.
River accident damages bridge in both directions.
A narrow-gauge railway is a railway with a track gauge narrower than 1,435 mmstandard gauge. Most narrow-gauge railways are between 600 mm and 1,067 mm.
A broad-gauge railway is a railway with a track gauge broader than the 1,435 mm used by standard-gauge railways.
A railroad switch (AE), turnout, or [set of] points (CE) is a mechanical installation enabling railway trains to be guided from one track to another, such as at a railway junction or where a spur or siding branches off.
In rail transport, track gauge is the distance between the two rails of a railway track. All vehicles on a rail network must have wheelsets that are compatible with the track gauge. Since many different track gauges exist worldwide, gauge differences often present a barrier to wider operation on railway networks.
A railway track or railroad track, also known as a train track or permanent way, is the structure on a railway or railroad consisting of the rails, fasteners, railroad ties and ballast, plus the underlying subgrade. It enables trains to move by providing a dependable surface for their wheels to roll upon. Early tracks were constructed with wooden or cast iron rails, and wooden or stone sleepers; since the 1870s, rails have almost universally been made from steel.
A loading gauge is a diagram or physical structure that defines the maximum height and width dimensions in railway vehicles and their loads. Their purpose is to ensure that rail vehicles can pass safely through tunnels and under bridges, and keep clear of platforms, trackside buildings and structures. Classification systems vary between different countries, and gauges may vary across a network, even if the track gauge is uniform.
A railroad tie, crosstie, railway tie or railway sleeper is a rectangular support for the rails in railroad tracks. Usually laid perpendicular to the rails, ties transfer loads to the track ballast and subgrade, hold the rails upright and keep them spaced to the correct gauge.
A light railway is a railway built at lower costs and to lower standards than typical "heavy rail": it uses lighter-weight track, and may have more steep gradients and tight curves to reduce civil engineering costs. These lighter standards allow lower costs of operation, at the price of lower vehicle capacity.
In railway engineering, "gauge" is the transverse distance between the inner surfaces of the heads of two rails, which for the vast majority of railway lines is the number of rails in place. However, it is sometimes necessary for track to carry railway vehicles with wheels matched to two different gauges. Such track is described as dual gauge – achieved either by addition of a third rail, if it will fit, or by two additional rails. Dual-gauge tracks are more expensive to configure with signals and sidings, and to maintain, than two separate single-gauge tracks. It is therefore usual to build dual-gauge or other multi-gauge tracks only when necessitated by lack of space or when tracks of two different gauges meet in marshalling yards or passenger stations. Dual-gauge tracks are by far the most common configuration, but triple-gauge tracks have been built in some situations.
With railways, a break of gauge occurs where a line of one track gauge meets a line of a different gauge. Trains and rolling stock generally cannot run through without some form of conversion between gauges, leading to passengers having to change trains and freight requiring transloading or transshipping; this can add delays, costs, and inconvenience to travel on such a route.
Gauntlet track or interlaced track, also gantlet track (AE) is an arrangement in which railway tracks run parallel on a single track bed and are interlaced in such a way that only one pair of rails can be used at any time. Since this requires only slightly more width than a single track, all rails can be carried on the same crossties/sleepers. Trains run on the pair of rails appropriate to their direction, track gauge or loading gauge.
A double-track railway usually involves running one track in each direction, compared to a single-track railway where trains in both directions share the same track.
The Finnish railway network consists of a total track length of 9,216 km (5,727 mi). The railways are built with a broad 1,524 mm track gauge, of which 3,249 km (2,019 mi) is electrified. Passenger trains are operated by the state-owned enterprise VR that runs services on 7,225 km (4,489 mi) of track. These services cover all major cities and many rural areas, though the coverage is less than the coverage provided by the bus services. Most passenger train services originate or terminate at Helsinki Central railway station, and a large proportion of the passenger rail network radiates out of Helsinki. VR also operates freight services. Maintenance and construction of the railway network itself is the responsibility of the Finnish Rail Administration, which is a part of the Finnish Transport Agency. The network consists of six areal centres, that manage the use and maintenance of the routes in co-operation. Cargo yards and large stations may have their own signalling systems.
A structure gauge, also called the minimum structure outline, is a diagram or physical structure that sets limits to the extent that bridges, tunnels and other infrastructure can encroach on rail vehicles. It specifies the height and width of station platforms, tunnels and bridges, and the width of the doors that allow access to a warehouse from a rail siding. Specifications may include the minimum distance from rail vehicles to railway platforms, buildings, lineside electrical equipment cabinets, signalling equipment, third rails or supports for overhead lines.
Railways with a railway track gauge of 5 ft first appeared in the United Kingdom and the United States. This gauge became commonly known as "Russian gauge", because the government of the Russian Empire chose it in 1843. Former areas and states of the Empire have inherited this standard. However in 1970, Soviet Railways re-defined the gauge as 1,520 mm.
The African Union of Railways is an organisation under the auspices of the new African Union dealing with railways. It is similar to the International Union of Railways (UIC).
Turkey has a state-owned railway system built to standard gauge which falls under the remit of the Ministry of Transportation and Infrastructure. The primary rail carrier is the Türkiye Cumhuriyeti Devlet Demiryolları (TCDD) which is responsible for all long-distance and cross-border freight and passenger trains. A number of other companies operate suburban passenger trains in urban conurbations.
Rail transport in Europe has diverse technological standards, operating concepts, and infrastructures. Common features are the widespread use of standard-gauge rail, high operational safety and a high share of electrification. Electrified railway networks operate at many different voltages, both AC and DC, varying from 750 to 25,000 volts, and signaling systems vary from country to country, complicating cross-border traffic.
The minimum railway curve radius is the shortest allowable design radius for the centerline of railway tracks under a particular set of conditions. It has an important bearing on construction costs and operating costs and, in combination with superelevation in the case of train tracks, determines the maximum safe speed of a curve. The minimum radius of a curve is one parameter in the design of railway vehicles as well as trams; monorails and automated guideways are also subject to a minimum radius.
The Main Line is a railway line in South East Queensland, Australia. It was opened in a series of sections between 1865 and 1867. It commences at Roma St Station in Brisbane and extends west 161 km to Toowoomba. It is the first narrow gauge main line constructed in the world. The section of the line from the end of Murphys Creek railway station to the Ruthven Street overbridge, Harlaxton is listed on the Queensland Heritage Register. The Murphys Creek Railway Complex, the Lockyer Creek Railway Bridge (Lockyer), the Lockyer Creek Railway Bridge and Swansons Rail Bridge are also heritage listed.