Standard gauge facts for kids

A standard-gauge railway is a railway where the distance between the inside edges of the rails is 1,435 mm (4 ft 8 ¹⁄₂ in). This measurement is also known as Stephenson gauge, named after George Stephenson, a famous railway pioneer. It's also called the international gauge or UIC gauge.

This type of railway track is the most common around the world. About 55% of all railway lines use this standard size. Most high-speed rail lines also use standard gauge, making it easier for trains to travel across different regions and countries.

History of Standard Gauge

As railways started to grow, a big problem was that different railway lines used different widths between their rails. This width is called the track gauge.

When a train reached a place where the track gauge changed, all the goods and passengers had to be moved from one train to another. This was called a "gauge break" and it took a lot of time and money. To solve this, many countries decided to use a "standard gauge" of 1,435 mm (4 ft 8 ¹⁄₂ in). This allowed trains to travel smoothly from one railway line to another, connecting places far and wide.

How the Standard Gauge Began

There's a fun story that the standard railway gauge comes from the width of chariot wheels in the Roman Empire. But experts say this story isn't quite true. The width of horse-drawn carts, which was about 5 ft (1,524 mm), probably influenced early rail widths. This was because it was a good width for a carthorse to fit between the shafts.

In the early days of railways in England, different coal mines used slightly different track widths. For example, some were 5 ft (1,524 mm), others 4 ft 4 in (1,321 mm), and some 4 ft 7 ¹⁄₂ in (1,410 mm).

George Stephenson, a key figure in railway history, worked a lot with coal mines in England. He liked the 4 ft 8 in gauge for the wagonways (early railways) in his area. He used it on his Killingworth line.

Stephenson's Stockton and Darlington railway (S&DR), which opened in 1825, also used the 4 ft 8 in (1,422 mm) gauge. This was because they already had hundreds of horse-drawn coal wagons that fit this size. Later, around 1850, this railway changed to the 1,435 mm (4 ft 8 ¹⁄₂ in) gauge, which is the standard we know today.

George Stephenson then used the 1,435 mm (4 ft 8 ¹⁄₂ in) gauge for the famous Liverpool and Manchester Railway, which opened in 1830. He even added a tiny bit extra (half an inch) to allow for easier movement on curves.

Because Stephenson and his son Robert were so successful, they helped build many other railways. This made the 4 ft 8 ¹⁄₂ in (1,435 mm) gauge (which is 1,435 mm (4 ft 8 ¹⁄₂ in)) very common in Britain.

During a time called the "gauge war", the standard gauge was sometimes called "narrow gauge" to make it sound less important than the wider 7 ft ¹⁄₄ in (2,140 mm) gauge used by the Great Western Railway.

Becoming the Standard

In 1845, a special group in the United Kingdom of Great Britain and Ireland decided that a standard gauge was best. A law was passed in 1846 that said new passenger railways in Great Britain should use the 4 ft 8 ¹⁄₂ in (1,435 mm) standard gauge. This was chosen because most existing lines already used this size.

Over time, even the wider railways in Britain changed to the standard gauge. By the 1890s, almost all railways in Britain used the standard gauge.

In the United States, especially in the Northeast, many railways also started using the same gauge because they bought early trains from Britain. All the different gauges in America slowly changed to the "almost standard" gauge of 4 ft 9 in (1,448 mm). A big change happened over just two days in May 1886, when many railways in the Southern United States switched their tracks!

In Europe, countries like France and Belgium first used a slightly different gauge. But soon, for trains to be able to travel between countries (like from Paris to Berlin), most European countries also adopted the standard gauge.

Early Railways and Their Gauges

In the early days of railways, many different track widths were tried. Some were wider or narrower than what became the standard. For example, the Great Western Railway used a very wide gauge of 7 ft ¹⁄₄ in (2,140 mm) for many years before changing to standard gauge.

Some railways were built with a gauge that was very close to standard, like the Killingworth Colliery railway which used 4 ft 8 in (1,422 mm). Over time, most of these "almost standard" lines also became true standard gauge.

Many famous early railways, like the Baltimore and Ohio Railroad in the US and the Liverpool and Manchester Railway in the UK, were built using what became the standard gauge. This helped spread its use around the world.

Modern Railways Around the World

Today, standard gauge is used in many countries. Here are just a few examples:

• Most of the national rail networks in countries like Canada, China, Germany, and the United States use standard gauge.
• Many city metro systems and tramways around the world, like the Algiers Metro in Algeria, the Sydney Metro in Australia, and the Delhi Metro in India, also use standard gauge.
• New high-speed rail lines being built in places like Tanzania and Laos are also using standard gauge to connect countries.

While most railways use the exact 1,435 mm (4 ft 8 ¹⁄₂ in) standard, some modern systems have very small differences. For example, the Toronto Transit Commission in Canada uses a slightly different gauge for its streetcars and subways, but its newer light rail lines use standard gauge. The MTR in Hong Kong uses 1,432 mm (4 ft 8 ³⁄₈ in) on some lines, which is very close to standard.

Non-rail use

Believe it or not, the idea of a standard width wasn't just for trains! In some parts of the United States, laws used to require road vehicles to have a consistent width between their wheels. This was so they could easily follow the ruts (grooves) made by other vehicles on the roads. These road widths were often similar to the railway standard gauge.

See also

• Standard Gauge (toy trains)
• List of track gauges#Standard gauge § Notes
• List of tram systems by gauge and electrification
• Track gauge
• Regulating the Gauge of Railways Act 1846