# Gauge (rail)

In rail transport, the track width is the distance between the track-guiding elements of the route. With conventional railways, these are the inner edges of the rail heads of a track . Sometimes the term “track width” is also used, but this is not correct, as the width is an external dimension and the track width is an internal dimension. In the case of rail vehicles, the gauge of the tracks is specified for which the running gear is designed. The distance between the flanges is called the track dimension .

The drives of rail vehicles are designed for use on tracks of a certain gauge. Vehicles with re-trackable drives are an exception to this rule . A transition of vehicles between networks with different track widths is only possible with considerable additional effort. That is why the track gauge is an important criterion for interoperability in rail transport . Conversely, the same track width does not mean that vehicles can cross over automatically. In most tram networks, for example, a transition to railway lines of the same gauge is not permitted because of different wheel and track geometries. The exclusion criterion is, in addition to the radius of curvature between the wheel running surface and the flange flank, in particular the distance between the rear surfaces of the wheel disks, which is important for guidance in the focal areas of switches and crossings, whose nominal dimension is 1360 millimeters with only very small tolerances in the European standard gauge network.

## definition

In Germany, the gauge is measured in accordance with Section 5 of the Railway Construction and Operating Regulations in the range between 0 and 14 millimeters below the top edge of the rail .

According to TSI HGV Infrastructure , Point 4.3.3.10, the track width is to be measured at a height of 14.5 millimeters with a tolerance of ± 0.5 millimeters below the upper edge of the rail.

In Switzerland, the gauge for standard gauge and meter gauge is measured 14 millimeters below the track surface, and for trams 10 millimeters under the track surface.

Naturally , no track width is defined for monorails .

## Track width tolerance

In connection with track gauges, only the nominal dimension ( referred to as the basic dimension in German railway building and operating regulations ) is usually given. The actual size, i.e. the actual, local track width, can differ considerably from the nominal size. For standard-gauge tracks (nominal size 1435 millimeters) in Germany, a tolerance range of up to 40 millimeters applies .

With the introduction of the Railway Building and Operating Regulations (EBO) in 1967, the track width - in accordance with the revision text of the technical unit of 1960 - was set at a basic dimension of 1435 mm with a lower limit of 1430 millimeters and an upper limit of 1465 millimeters (for main tracks ) or 1470 millimeters ( siding ). Track extensions in curved tracks with a radius of less than 200 meters, which were previously linked to a decree by the Federal Minister of Transport, have been incorporated into the EBO.

## Gauge differences

The railway companies chose different gauges, as can be seen from the list of gauges . The choice of a certain gauge had technical, military and economic reasons.

Three- rail tracks of the Brohltalbahn in the Brohl reloading station (2011)

From a military point of view, there was often concern that the enemy might use the railway network for their own purposes in the event of war . For this reason, the track width differences to the neighboring country were often deliberately chosen so that neither a transition of the vehicles nor a use of the sleepers to build a three-rail track was technically possible.

From an economic point of view, there was often an interest in preventing competing companies from using their own infrastructure with their vehicles. Some US tram companies acted for such motives, trying to prevent their routes from being used by competing Interurbans or conventional railroads to handle local freight traffic. At the time of the financial decline of privately financed local public transport in the 1920s, the different track widths turned out to be a disadvantage, because the declining income from passenger transport could not be offset by additional freight transport. Examples of such systems can be found in Philadelphia and Pittsburgh .

Railway companies also chose their gauges for financial reasons. The costs for building a narrow-gauge line are lower than for a standard-gauge line, because the narrower arc radii allow narrow-gauge railways to adapt better to the terrain, thereby avoiding expensive engineering structures. Narrow-gauge wagons have lower demands on the structural strength of their car bodies .

The vehicles can be built lighter, which is particularly advantageous on steep mountain railways . Low Wagenzugmassen are at funiculars particularly important, so they often operate on narrow gauge.

Thanks to the inexpensive operation, many narrow-gauge railways were able to survive despite relatively modest traffic. However, because of their smaller vehicles, European narrow-gauge railways usually have a lower transport capacity than railways with larger gauges and hinder the expansion of the road where they are built along roads or even share the road surface. In Japan and southern Africa , many narrow-gauge railways achieve services that are comparable to, or even surpass, European standard-gauge railways.

The normal track or control track 1435 millimeters is distributed worldwide to 75 percent on the railway network, track widths below this measure occupy 13 percent and greater gauges 12 percent of the rail network (approximate values).

## Important gauges

Graphic comparison
Distribution of important gauges in the world

### 1676 mm

1676 mm: Indian Railways electric locomotive in front of the Hyderabad-Gujjangivalasa Intercity Express

Mainly used in India , Pakistan , Bangladesh and Sri Lanka as well as Chile and Argentina , the 1676 mm (5½ feet) gauge is one of the largest broad gauge , it is also called the Indian broad gauge .

### 1668 mm

The slightly different Iberian broad gauge of 1668 millimeters was created by averaging the Spanish (1672 millimeters = six Castilian feet ) and Portuguese (1665 millimeters = five Portuguese feet) broad gauge to make it easier to cross the carriages.

### 1600 mm

1600 mm: Broad gauge passenger train of the Irish Córas Iompair Éireann

1,600 mm gauge (5¼ feet) rail networks exist primarily in Ireland and Northern Ireland, as well as parts of Australia (states Victoria and South Australia ) and on 20 percent of the Brazilian network. It is also called the Irish broad gauge . The state of Baden also initially built this gauge for strategic military reasons, but after a few decades it converted it to the standard gauge of the neighboring railways.

### 1588/81 mm

The track gauge known as the Pennsylvania gauge (5 feet 2½ inches) was common in the US state of Pennsylvania . It still occurs today on streetcar networks such as the Subway – Surface Trolley Lines in Philadelphia and the New Orleans tram .

### 1520 mm

1520: For the vehicle exchange between Finland and the rest of the broad gauge network, the difference in Spurweitenmaß in the picture does not matter a trainset Helsinki-St. Petersburg of the Finnish VR series Sm6

In Russia and the other states of the Commonwealth of Independent States (CIS), but also in Mongolia , Estonia , Latvia and Lithuania , a broad gauge with 1520 millimeters is used, it is also called Russian broad gauge . The nominal dimension used to be 1524 millimeters (5 feet), the reduction by four millimeters was intended to reduce the track clearance and thus reduce wear while maintaining the wheelset dimensions.

In connection with the wheel set's track dimension of 1511 millimeters, the track clearance corresponds to the normal conditions in the European standard track network. In Finland , the nominal dimension with otherwise identical tolerances (the smallest dimension is 1515 millimeters) is still 1524 millimeters, but new tracks are also being laid with 1520 millimeters gauge.

### 1435 mm

The 1,435 millimeters (4 feet 8½ inches) wide standard gauge is in much of Europe, the route network of which the European Union to 87 percent, and in North America and China track almost exclusively used. The standard gauge network in these countries alone already represents more than 40 percent of the global railway network. In Japan this gauge is used for Shinkansen routes.

However, there are differences in the distance between the rear surfaces of the wheel sets and, related to this, in the guide and groove widths in the focal area of ​​switches and crossings. While the nominal dimension of the distance between the rear surfaces of the wheel sets in Europe, the Middle East and North Africa is 1360 millimeters, in North America and China it is 1353 millimeters. The tolerances are low, a vehicle exchange between the different areas usually requires a wheel set change despite nominally the same track width. Tram networks usually also have different back space distances (in this context often called wheel back dimensions ), but because of the different heights of the control arms, compromise wheel tires are possible here, which enable the car transition.

### 1067 mm

1067 mm: Train on the Kagoshima Main Line in Japan on Cape Gauge

In southern Africa , Japan and New Zealand, as well as in Australia's states of Western Australia , Queensland and Tasmania , the 1067 millimeter (3½ foot) Cape Track is used. Other countries with Cape Gauge are Ecuador , Nicaragua (mined), Costa Rica , Nigeria , Ghana and Sudan . It is also used by the Hong Kong tram .

### 1000 mm

The meter gauge (1000 millimeters) is the most widely used gauge in Brazil and on narrow-gauge railways in Germany, Spain, Switzerland and other countries. This gauge is also used by numerous tram operators around the world. In South America, the meter gauge also plays an important role in Argentina and Bolivia . The gauge also occurs in Chile and Cuba . About two thirds of the railways in Tunisia have meter gauge, as do the railways in Kenya, Tanzania, Uganda, Ethiopia, Cameroon, Madagascar, Benin, Togo, Ivory Coast-Burkina Faso, Guinea (partially), Senegal-Mali. In Asia, the meter gauge is widespread in India, Bangladesh, Thailand, Myanmar, Malaysia, Cambodia and Vietnam.

For the wheel flange dimensions and the guide and groove widths, what has already been said for the standard gauge applies; the identical gauge alone is not sufficient for the wagon transition.

### 950 mm

950 millimeters was the predominant gauge for narrow-gauge railways in Italy and for narrow-gauge lines that were built under Italian control. Eritrea also has the 950 millimeter track. It is also called Italian meter gauge and is based on a different definition of gauge. The meter was measured from the middle of the rail heads and running surfaces (see also Russian broad gauge).

### 914 mm

The gauge of 914 millimeters (three British feet), often also given as 915 millimeters, is used in the United States and the United Kingdom , among others . But you can also find them on various sugar cane railways in Cuba and Indonesia . The railways in Guatemala (closed), El Salvador and Colombia as well as some railways in Peru also have this gauge. The iron and tram lines of Ferrocarril de Sóller SA (FS) have retained the gauge of 914 mm, while the other railways on Mallorca have been switched to meter gauge by FEVE . The tram Chemnitz had before their conversion to standard gauge, a gauge of initially 915 millimeters. This comparatively narrow gauge was supposed to be extended to meter gauge in ten millimeter steps by rail renewals, but as a result of the First World War and the events that followed, only one step to 925 millimeters was used until narrow-gauge operation was discontinued in 1988.

### 900 mm

900 mm: Train of the "Molli" in Bad Doberan (1990)

This gauge is common on industrial and mine railways, one example being the mine railways in the central German lignite area. Public transport routes such as the Bad Doberan – Kühlungsborn route on the Mecklenburg Baltic Sea coast were also created through the use of inexpensive superstructure and vehicle material . The measure was also used for trams, for example the tram networks of Linz and Lisbon are in operation .

### 891 mm

The gauge of 891 millimeters (= three old Swedish feet) is only used in Sweden . The Roslagsbanan in Stockholm still uses this gauge.

### 800 mm

This gauge is particularly common on Swiss mountain railways and cog railways. It should reduce the effort involved in building the track and improve the curve travel compared to the meter gauge and offer more space for the installation of gear drives than even narrower gauges. However, a coherent network did not develop.

### 762 mm

The 762 millimeter (2½ foot) gauge is used in all British influenced regions.

### 760 mm

760 mm: The Bosnian gauge is widespread on the narrow-gauge railways in Austria; the vehicles on the narrow-gauge Zillertal Railway appear delicate in the background compared to the standard-gauge ÖBB passenger coaches

The 760 millimeter wide Bosnian gauge was first introduced in Bosnia , after which it was increasingly used in the former Austria-Hungary and its successor states. The works railway when the Arlberg railway tunnel was built (1882–1884) had this gauge.

### 750 mm

750 mm: The Waldenburgerbahn will probably run with this gauge until the planned change of gauge from April 2021

The 750-millimeter narrow-gauge was often used, for example on the Saxon narrow-gauge railways , which can now be found on the Fichtelbergbahn, among other things . In addition to other routes in Germany, such as the Öchsle , it can also be found on the Swiss Waldenburgerbahn , as well as on many industrial railways such as the international Rhine regulation railway . This track width is the smallest on which standard or wide-gauge vehicles can be safely transported using trolleys or trolleys .

### 600 mm

The track width of 600 millimeters was mainly used on non-public industrial railways and field railways as well as in mining. During the First World War , both the French and English as well as German military field railroad systems operated in this gauge. In addition, railways with public transport in 600-millimeter lanes were built. B. the Mecklenburg-Pomerania narrow-gauge railway .

## Change of gauge

The different track widths were initially driven by different vehicles. However, they represent a correspondingly large obstacle to through traffic. Over time, different methods have developed how goods and people are transported across different track widths.

Different track widths with a slight difference (up to around 15 millimeters) can possibly be driven on with the same vehicle. It is necessary that the permitted track clearance is maintained in both systems. By using special wheel sets with a wider tread, which allow a larger track clearance, slightly larger track width differences can be overcome (depending on the permissible speed and other parameters, in individual cases up to 60 millimeters).

A solution that is often encountered is for people to change trains between different trains or for goods to be loaded from one car into another. The apparently simple solution, however, is uncomfortable for travelers and labor-intensive and slow in freight transport, and the risk of damage to the cargo increases considerably. Often the vessel sizes also differ. This complicates the provision and utilization of the car space.

### Use of swap bodies

Containers simplify reloading from normal to narrow gauge. Waggon Rhätischen web with an interchangeable container of a retail company .

Since nowadays containers and swap bodies with standardized dimensions are used for the transport of goods on different modes of transport, this system is also suitable for the transition between gauges. However, containers make poor use of the loading capacity of most railroad networks. In particular in freight traffic with the Iberian Peninsula , the swap bodies of complete trains are replaced by powerful crane systems . The underframes of the wagons each remain on one track. Special wagons, in particular sliding-wall wagons, have been developed for such transports. In contrast to containers, their superstructures are usually not transported by other means of transport ( trucks or ships ). The disadvantage is the required parking space for the free underframes at the lane changing stations.

### Track gauge change through on-board adaptation

#### Exchange of axles / bogies

In certain railway vehicles, the axles or bogies can be exchanged, so that a changeover to a different gauge is possible. However, this assumes that the vehicles otherwise match (e.g. clutch , brake system ), or that other parts are converted. Because of the high proportion of two-axle vehicles, it is common to change wheelsets, especially in freight traffic to the Iberian Peninsula and Finland. The proportion of freight wagons running through the standard gauge network from the Eastern European broad gauge network has declined sharply in recent years.

In the network of the former Soviet Union , bogie cars are used almost exclusively, the bogies are exchanged as a whole. The different pulling and pushing devices require the use of coupling wagons . The bogies and couplings are changed when traveling on the railways of the former Soviet Union. Until 1994, through trains to Spain and Portugal were also run in the same way. Since then, only Talgo wagon trains (RD and Pendular) have been used for this purpose (see below), with the commissioning of the continuous standard gauge connection between Perpignan and Barcelona, ​​operation with passenger trains capable of changing gauge across the border was completely discontinued.

The Renfe and CP also use the European screw coupling, but due to the larger spacing between the solebar, especially in two-axle wagons, the buffer spacing in Spain and Portugal was 200 millimeters larger until the 1990s, in 1950 instead of 1750 mm. To compensate, transferable wagons received extra-wide buffer plates. On the French Corail cars , the replicas in Spain and Portugal and on the Talgo Pendular end cars, these extra-wide buffer plates have been preserved to the present day.

#### Trestle / trolley traffic

In particular, for the traffic between the main railway network and shorter narrow-gauge routes, trolleys or trolleys ( called trolleys in Switzerland ) have been developed, whereby a standard-gauge railway trolley is pushed onto the trolleys or trolleys at special systems and then continues "piggyback". Due to the low share of freight traffic on branch lines today, trolleys and trolleys are rarely used.

On standard-gauge lines, trolleys are used to transport new vehicles for narrow-gauge and trams.

#### Automatic re-gauging

The Spanish company Talgo developed a system in which the wheels sit individually on stub axles which, together with their bearings, can be moved sideways. To change the gauge, the train has to use a special gauge change facility . The axle bearings are unlocked, the relieved wheels are pushed apart or together by guides until they are in a position for the other track width and are then locked again in this position. Talgo trains operate both for passenger traffic between Spain and France and for domestic traffic. In addition to Talgo wagons, locomotives with powered bogies that can be re -tracked in Talgo gauge changing systems have also been developed.

Further systems of re-trackable drives also allow the re-gauging of loaded wheel sets and the transition of vehicles between normal and meter gauge.

### Track gauge change through adaptation to the superstructure

The Spanish government commissioned an expert opinion in 2007 to determine the costs and benefits of a nationwide change in gauge from the current 1668 millimeters to the European standard gauge (1435 millimeters). The newspaper El Pais estimated in 2007 that an adaptation of the 12,000 km long rail network would take at least until 2020.

## Gauges for model railways

There are also different track widths for model railways , which depend on the reproduction scale and the track width of the prototype selected. The world's most widespread nominal size H0 on a scale of 1:87 uses a gauge of 16.5 millimeters, which corresponds to the standard gauge of 1435 millimeters on this scale.

## reception

• 89 millimeters - the difference between the original Russian broad gauge and standard gauge gives the film about Belarus (2004–2005) its title
• In the audio book Well then, good night! Bjarne Mädel reads the world's boring audio book, among other things, a chapter: Railway track widths - an overview .

## literature

• GH Metzeltin: The gauges of the railways - A lexicon on the battle for gauge . German Society for railway history e. V., Karlsruhe 1974
• Railway technical review: E-locomotive for two gauges . Eisenbahntechnische Rundschau 54 , 2005. 5. Eurailpress Hamburg, p. 323 f.