Standard gauge

As railways developed and expanded one of the key issues to be decided was that of the rail gauge (the distance between the two rails of the track) that should be used. The eventual result was the adoption throughout a large part of the world of a standard gauge allowing inter-connectivity and the inter-operability of trains. The distance between the inner sides of the rails in this gauge is 1435 mm (4 ft 8½ in). Currently 60% of the world's railway lines are built to this gauge. It is also named Stephenson gauge after George Stephenson.

In Great Britain the standard gauge was at first 4 ft 8 in (1422 mm) but it was soon widened slightly. Parts of the United States rail system, mainly in the northeast, adopted the same gauge because some early trains were purchased from Britain. However, until well into the second half of the 19th century Britain and the USA had several different track gauges. The American gauges slowly converged as the advantages of equipment interchange became more and more apparent; the destruction of much of the South's broad gauge system in the American Civil War hastened this trend.

List

List of standard gauge, 4ft 8½in (1435 mm), by country.

Origin

The pioneer of railways, George Stephenson, spent much of his early engineering career working in the mines of County Durham. There, the pony-pulled coal mine rail systems all used this gauge. The Stockton and Darlington Railway (SD&R), the world's first steam-powered railroad, was mainly used to transport coal from the mines to British seaports; the SD&R's track gauge was required to accommodate the horse-drawn carts used in the mines. This influence appears to be the main reason that this particular gauge became the standard, and its usage became more widespread than any other gauge.

Subsequently, engineers have shown that a narrow gauge is less than ideal: despite usually offering cheaper construction, a smaller gauge restricts speeds due to a reduced load stability. Broader gauges are theoretically more stable at speed and allow larger, wider, heavier loads. According to Isambard Kingdom Brunel's studies the optimum gauge for a rail system (and the one he originally used on his Great Western Railway) is 7 ft ¼ in (2140 mm).

In the UK, a Royal Commission in 1845 reported in favour of standard gauge on the grounds that its network was eight times larger than that of the rival 7 ft ¼ in (2140 mm) gauge adopted principally by the Great Western Railway. The subsequent Gauge Act of 1846 ruled that new railways in Great Britain should be built to standard gauge, but allowed the broad gauge companies to continue expanding their networks. After an intervening period of mixed-gauge operation (tracks were laid with three running-rails), the Great Western finally converted its entire network to standard gauge in 1892.

A popular urban legend traces the origin of the 4 ft 8½ in (1435 mm) gauge even further back than the coalfields of northern England, pointing to the evidence of rutted roads marked by chariot wheels dating from the Roman Empire. This legend is regarded as mostly false, however, except inasmuch that it shows a historical tendency to place the wheels of vehicles approximately 5 ft (1500 mm) apart.

See also: Rail gauge, Broad gauge, Narrow gauge, Dual gauge.

Ideal gauge

There has been much controversy about what constitutes the "ideal gauge". From a design point of view, a train can travel faster around a given radius of track if the gauge is wider, as the centre of gravity of the train is therefore further displaced from the wheels, which in turn lowers the angle between the wheel's lower contact surface to the centre of gravity, and horizontal. Given that one can tailor either the track radius for train speed, or the train speed for track radius, gauge in some cases may not be as important as interoperability.

There are many examples of high speed and high mass applications on narrow gauges throughout the world, suggesting that gauge is less important than the original supporters of broad gauge or narrower gauges, held it to be:

The heaviest trains in the world run on standard gauge track in Australia, North America and Mauritania. Gauge is not the limiting factor in running heavier trains.
The fastest trains in the world also run on standard gauge in Japan and Europe, where speeds over 300 km/h are attained.
Very heavy trains run on the narrow gauge of 3 ft 6 in (1067 mm) in Queensland (Australia) and South Africa, on track as strong as heavy standard gauge track. A narrow gauge does not seem to materially affect the weight of trains that can be run.
Fairly fast trains can run on narrow gauge track, as can be seen in Queensland.
It is possible to build a light standard gauge line about as cheaply as a narrow gauge line.
It is possible to build a narrow gauge line to as heavy-duty a standard as a standard gauge line.
Loading gauge, structure gauge, axle load, compatibility of couplings, continuous brakes, electrification system, railway signal systems, radio systems and rules and regulations are also important.

With the benefit of hindsight, little was gained by building railway systems too narrow (down to about 3 ft (900 mm)) or too broad (up to about 7 ft (2100 mm)) gauges, and this was at the cost of nil interoperability.

Only in gauges of less than 3 ft (900 mm) can a railway be built significantly more cheaply than is possible with standard gauge, and only then in mountainous terrain, or where a low capacity line is required, or with industrial railways where through running is not required.

It can be argued therefore, that the original uniform gauge adopted by Stephenson in 1830 can serve most of the tasks performed by gauges from 3 to 7 ft (900 to 2100 mm), albeit with a mini gauge of about 2 ft (600 mm) for cane tramways, underground mine, mountain, construction, temporary and military railways, plus children's railways.

For interoperability, if possible, the mini-gauge trams should be able to piggyback on top of standard gauge flat wagons, to reach workshops and other narrow gauge lines to which they are not otherwise connected. Piggyback operation by the trainload occurred as a temporary measure between Port Augusta and Marree during gauge conversion works in the 1950s.

Break of Gauge

Main article: Break-of-gauge

When a railway line of one gauge meets another railway line of a different gauge, there is a break of gauge. A break of gauge adds cost and inconvenience to traffic that must pass from one system to another.

An example of this is on the Transmanchurian Railway, where Russia and Mongolia use broad gauge while China uses the standard gauge. At the border, each carriage has to be lifted in turn to have its bogies changed. The whole operation, combined with passport and customs control, can take several hours.

Model railway

Main article: Rail transport modelling

In American model railroading, Standard gauge was originally an effort by Lionel Corporation to corner the U.S. market in the early years of the 20th century. Lionel standardized its offerings on three-rail track with a gauge of 2 1/8 in (54 mm) between the outer rails, making it incompatible with Gauge 1 offerings from European manufacturers. Lionel then registered a trademark on Standard Gauge. Other American companies followed Lionel's lead, standardizing on Lionel's new standard but calling it Wide gauge in order to avoid infringing on Lionel's trademark.

Standard gauge fell out of favour in the 1930s because of its high cost, and Lionel discontinued its Standard gauge offerings in 1940.

Although scale modeling was not of primary concern, Standard gauge's scale is generally accepted at 1:26.59, making it somewhat smaller than G scale.

More recently, standard gauge has come to mean scale modelling in which the track is accurately scaled to real-world standard gauge. This is opposed to narrow gauge modeling, which models real-world narrow gauge, or off-scale modeling, where track is not true to scale, such as in O gauge.

References

External links

Snopes History of standard gauge dating from Roman times (Snopes labels this as false).

Rail gauge | Model railroad scales