1,435 millimeters. This single measurement connects railways in Europe, North America, China, and large parts of the world. It is the standard gauge. It determines whether a train can travel from Hamburg to Vienna without having to change its wheels even once. But what’s the story behind this measurement? Why are there different track gauges around the world? And what role does track gauge play in switch technology?
What is track gauge—and how is it measured?
The track gauge is the clear distance between the inner edges of the rail heads of the two rails in a track. It is measured at a clearly defined point: 14 mm below the top of the rail. This precise specification is no coincidence—it prevents measurement tolerances caused by wear on the rail heads from skewing the result.
In Germany, the measurement and use of track gauge are regulated by the Railway Construction and Operating Regulations (EBO). These regulations specify the tolerance range within which the track gauge must remain during normal operation—and when a line must be closed.
The world of track gauges is divided into three categories:
| Category | Definition | Typical width | Use |
| Narrow-gauge | Narrower than 1,435 mm | 750 mm, 1,000 mm, 1,067 mm | Mountain railways, industrial railways, regional railways |
| Standard Gauge / Regular Gauge | Exactly 1,435 mm | 1,435 mm | Europe, North America, China, High Speed |
| Wide Track | Wider than 1,435 mm | 1,520 mm, 1,668 mm | Russia, CIS countries, Spain (formerly), India |
About 60% of the world’s rail network is standard gauge—also known as normal gauge. It has proven to be an ideal compromise between stability, speed, and cost-effectiveness.
Where does the measurement of 1,435 mm come from—really?
One of the most persistent legends in railway history claims that standard gauge derives from the track width of Roman chariots. As memorable as this story is, it is not historically substantiated.
What is documented: In 1822, George Stephenson built the first public railroad with a track gauge of exactly 1,435 mm. This measurement corresponds to four feet and eight and a half inches—an English unit of length that Stephenson adopted from the coal mine railroads in northern England, where he grew up. In 1846, the British Parliament finally established standard gauge by law as the mandatory standard. The rest is railroad history.
Why don’t Russia and Spain use standard gauge tracks?
The answer lies in history, politics, and strategy—not in technology.
Russia uses a 1,520 mm broad gauge. In the 19th century, the Tsarist Empire wanted to prevent enemy troops from using the railroad as a route of attack. A different track gauge simply made the rapid transport of troops from the West impossible—a decision that to this day forces millions of freight cars to stop at the EU’s external borders.
Spain and Portugal chose the Iberian broad gauge (1,668 mm) based on similar considerations and because of the mountainous terrain, which made wider vehicles more stable. It was not until the construction of the AVE high-speed rail network that Spain returned to standard gauge.
Today, highly complex systems are being built at the points where different track gauges meet: wheel sets are changed, and track-gauge-changing devices are used. This places the highest demands on switch technology—every component must be tailored to the system in use on each side of the border.
What railroad track gauges are there around the world? A complete list
| Track width | Description | Regions & Countries |
| 1,676 mm | Indian Broad Gauge | India, Pakistan, Sri Lanka, Argentina |
| 1,668 mm | Iberian Broad Gauge | Portugal, older Spanish routes |
| 1,524 mm | Russian/Finnish Wide-Gauge | Russia, CIS countries, Finland, the Baltic states |
| 1,435 mm | Standard Gauge / Regular Gauge | Europe, North America, China, North Africa, parts of Asia |
| 1,067 mm | Cap Track | South Africa, Japan (regional railways), New Zealand, Australia (in part) |
| 1,000 mm | Meter Gauge | Switzerland (private railroads), Brazil, India (regional network), Vietnam |
| 891 mm | Swedish narrow gauge | Historic Narrow-Gauge Railroads in Sweden |
| 760 mm | Bosnian Trail | Parts of the Balkans, historic military and field railways |
| 600 mm | Narrow-gauge railway / Industrial railway | Mining, sugarcane railroads, peat railroads |
Note: In some countries, multiple track gauges coexist. In Japan, for example, Shinkansen trains run on standard gauge (1,435 mm), while the traditional regional network is designed for narrow gauge (1,067 mm). This makes direct connections between the two networks impossible without changing trains.
Trams and Subways: A Special Case in Urban Transit
Trams and subways follow their own rules. In Germany, most streetcars run on standard gauge (1,435 mm), which allows them to be integrated into the larger rail network. Some light rail systems—such as those in Graz or on parts of the meter-gauge network in Switzerland—use different track gauges.
Subways are generally closed systems: They operate on their own infrastructure without connecting to long-distance rail services. The track gauge was often established for historical reasons—London’s Underground runs partly on 1,435 mm and partly on other gauges, depending on when each line was built.
The same applies to light rail infrastructure: The switch components used must match the track gauge exactly. Even slight deviations in the area of the rail heads can lead to wear, noise, and, in the worst case, operational disruptions.
Narrow-gauge: Flexible, affordable—but slow
Narrow-gauge railroads have one key advantage: they can navigate much tighter curve radii than standard-gauge railroads. This makes them ideal for mountainous regions, historically developed urban areas, or industrial facilities with limited space.
The trade-off: Narrow-gauge railways are generally limited to speeds between 30 and 80 km/h. This is not an option for long-distance freight and passenger transport.
Where narrow-gauge railroads meet the standard-gauge network, technically sophisticated transition structures are built. The switch technology at these points is highly complex—every component must be precisely matched to the respective track gauge down to the millimeter. This ranges from the switch heart, which guides the track at intersections, to the slide plates on which the switch blade moves.
Wide-track: Stable, heavy, powerful
Wide-gauge railways offer greater stability and can carry significantly heavier loads than standard-gauge railways. This makes them particularly attractive for freight transport—Russia transports billions of metric tons of raw materials across the continent each year on its wide-gauge network.
The downside: wide-gauge tracks are more expensive to build and maintain. And at the boundaries between rail systems—such as between Russia and Poland—there are marshalling yards where railcars are transferred to different wheel sets. This logistical effort affects thousands of trains every day.
How is track gauge related to travel speed?
Track gauge directly affects how fast a train can travel safely. Standard gauge, with a width of 1,435 mm, is the key to high-speed rail: Modern trains travel at speeds of 300 to 320 km/h on this gauge—and in Japan, they even reach 320 km/h on the Shinkansen network.
This requires not only the correct track gauge, but also the quality of the entire track structure. The rail profile, ties, ballast, and—crucially—the precision of the switch components all play a role here.
This is precisely where track gauge becomes a key requirement for switch technology: Every component must be tailored to the specific rail profile and track gauge used. This is especially true for safety-critical locking systems on turnouts, as the article on EBA certification in railway technology demonstrates—because certifications always apply to specific track gauges, not across the board.
What does track gauge mean in practical terms for switch technology?
Turnouts are the points in the rail network where trains change direction. Each turnout consists of a series of components, all of which must be tailored to the respective track gauge.
For use on standard-gauge tracks with rail profiles 49E5, 54E4, and 60E2, the following points are crucial:
- Switch blade: Must fit precisely against the cheek rail—the distance depends on the track gauge.
- Centerpiece: The intersection of two tracks must match the track gauge exactly so that wheels can pass over them safely.
- Sliding Chair Plates: Enable low-friction movement of the switch blade and are specific to each track profile.
- Turnout Lock: Secures the switch blade in the set position—and must be compatible with the track gauge.
- Wheel Guide: Guides the wheel through the center section and prevents derailments.
What role does interoperability play in Europe?
Interoperability is the great promise of the European rail area: a train should be able to travel from Lisbon to Warsaw without encountering any technical obstacles. Standard gauge is the foundation for this—but it is not enough on its own.
The EU directives on interoperability stipulate that all systems—from signaling technology to turnout technology—must comply with harmonized standards. This is directly reflected in approval procedures such as those of the EBA: components are not approved in general terms, but rather for specific profiles and switch types—precisely because interoperability requires precision.
Our introductory article on the German rail network explains how the rail network in Germany works and what role switch technology plays in it.
How does track gauge affect track and rail construction?
When building new rail lines, the choice of track gauge is one of the earliest and most far-reaching decisions. It determines:
- The threshold value and the threshold spacing
- The amounts of gravel and the widths of the base course
- The Geometry of Turnouts at Train Stations and Interchanges
- Compatibility with existing rolling stock
In modern track and rail construction, these decisions are also closely linked to welding technology: Today, rail joints are welded seamlessly—using methods such as thermite welding or machine-assisted burn-off butt welding. Both methods work regardless of track gauge—but are tailored to the respective rail profile.
Outside or Inside Curved Turnout: When the Track Gauge Determines the Turnout Type
Special requirements apply on curves. An outside curve switch branches off to the outside, while an inside curve switch branches off to the inside. Both types have different geometries—and place different demands on the track gauge accuracy of the components.
Especially in tight curves, such as those found on light rail or streetcar lines, tolerances of just a few millimeters can determine whether a switch operates smoothly—or whether it leads to increased wear and breakdowns.
Conclusion: A measure that brings everything together
1,435 mm. This measurement is more than just a technical standard—it is the foundation for a connected, high-performance rail system. Standard gauge connects continents, enables high-speed rail, and creates the conditions for efficient freight transport.
At the same time, the variety of global track gauges shows that there is no one-size-fits-all solution. Every track gauge has its own justification—depending on the topography, the transportation task, and historical developments.
What remains is the requirement for all components: They must be precisely matched to the respective track gauge—from the rail to the switch lock. Bharat Forge CDP Railsystems manufactures exactly these components—and stands by your side as a partner from planning through maintenance.
FAQ: Frequently Asked Questions About Track Gauge in Railway Construction
What is the track gauge for railroads?
The track gauge is the clear distance between the inner edges of the rail heads of both rails in a track, measured 14 mm below the top of the rail. In Germany and throughout Europe, standard gauge (1,435 mm) is the norm.
What is the difference between standard gauge, narrow gauge, and broad gauge?
Standard gauge is exactly 1,435 mm. Narrow gauge refers to anything narrower—typically 1,000 mm or 1,067 mm. Wide gauge refers to any track that is wider—such as the Russian gauge of 1,520 mm. The track gauge affects stability, operating speed, and vehicle compatibility.
Why is the standard track gauge exactly 1,435 mm?
This measurement dates back to George Stephenson, who built the first public railway in 1822 and adopted the track gauge used by the coal mine railroads in northern England—four feet and eight and a half inches. In 1846, this measurement was established by law as the standard in Great Britain and spread from there throughout the world.
How is track gauge regulated in Germany?
In Germany, the Railway Construction and Operating Regulations (EBO) govern the permissible tolerances for track gauge during operation. The standard gauge of 1,435 mm is the norm for the main network. Deviations beyond certain limits result in the closure of the line.
What is the track gauge for subways and streetcars in Germany?
Most trams and many subways in Germany run on standard gauge (1,435 mm). However, there are exceptions: Some older light rail systems use different track gauges, which have been retained for historical reasons.
Why does Russia use a different track gauge than Europe?
Russia uses a 1,520-mm broad gauge. This decision was made in the 19th century for strategic reasons: a different track gauge was intended to make it more difficult for enemy troops to use the railroad as a route of attack. At today’s EU external borders, this results in time-consuming border-crossing procedures.
What does the track gauge have to do with switch locks?
Turnout locks secure the turnout switch in its set position. Since the geometry of the turnout—and thus the lock—depends directly on the track gauge and the rail profile used, all components must be matched to the respective track gauge. An approval issued by the Federal Railway Authority (EBA) always applies to specific rail profiles; it is not a blanket approval.
What is the 1,067-mm gauge?
The Cape gauge (1,067 mm) is named after the Cape of Good Hope, where it was first used on a large scale. Today, it is primarily found in South Africa, Japan (regional network), New Zealand, and Australia. It is wider than typical narrow-gauge railways but narrower than standard gauge—a compromise that makes mountainous regions accessible.