The axle load of a wheeled

vehicle A vehicle () is a machine designed for self-propulsion, usually to transport people, cargo, or both. The term "vehicle" typically refers to land vehicles such as human-powered land vehicle, human-powered vehicles (e.g. bicycles, tricycles, velo ...

is the total weight bearing on the

roadway A carriageway (British English) or roadway (North American English) is a width of road on which a vehicle is not restricted by any physical barriers or separation to move laterally. A carriageway generally consists of a number of traffic lane ...

for all wheels connected to a given

axle An axle or axletree is a central shaft for a rotation, rotating wheel and axle, wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to the vehicle, with the wheels rotating around the axle. In ...

. Axle load is an important design consideration in the engineering of roadways and railways, as both are designed to tolerate a maximum weight-per-axle (axle load); exceeding the maximum rated axle load will cause damage to the

road A road is a thoroughfare used primarily for movement of traffic. Roads differ from streets, whose primary use is local access. They also differ from stroads, which combine the features of streets and roads. Most modern roads are paved. Th ...

way or railway tracks.

Railway use

railway Rail transport (also known as train transport) is a means of transport using wheeled vehicles running in railway track, tracks, which usually consist of two parallel steel railway track, rails. Rail transport is one of the two primary means of ...

s, a given section of tracks is designed to support a maximum axle load. The maximum

load is determined by train speeds, weight of rails, density of sleepers and fixtures, amount and standard of

ballast Ballast is dense material used as a weight to provide stability to a vehicle or structure. Ballast, other than cargo, may be placed in a vehicle, often a ship or the gondola of a balloon or airship, to provide stability. A compartment within ...

, and strength of bridges and earthworks. Higher operating speeds can be achieved by reducing axle loads and increased load-carrying capacity. Operating above the specified load can cause catastrophic failure of track components. The diameter of the wheels also affects the maximum axle load of a Talgo RD wagon.

United Kingdom

The standard rail weight for British railways is now . Before the 1990s, most

diesel locomotive A diesel locomotive is a type of railway locomotive in which the prime mover (locomotive), power source is a diesel engine. Several types of diesel locomotives have been developed, differing mainly in the means by which mechanical power is con ...

s were built to a maximum axle load of so the maximum locomotive weight was for a four-axle locomotive and for a six-axle one. Higher axle loads are now permitted, e.g. the Class 67 locomotive is a four-axle machine weighing , giving on each axle.

Australia

The Fortescue railway uses rail on concrete sleepers and has a maximum axle load of , which was the highest axle load of any railway in the world. In 2011, it was proposed to increase the axle load of the railway to .

Kenya

In 2022, sixteen new

metre-gauge Metre-gauge railways ( US: meter-gauge railways) are narrow-gauge railways with track gauge of or 1 metre. Metre gauge is used in around of tracks around the world. It was used by several European colonial powers including France, Britain and ...

locomotives were supplied by

CRRC CRRC Corporation Limited (known as CRRC) is a Chinese state-owned and publicly traded rolling stock manufacturer. It is the world's largest rolling stock manufacturer in terms of revenue, eclipsing its major competitors of Alstom and Siemens. ...

with axleloads of 12.5 tonnes, 14 tonnes, and 18 tonnes respectively.

Bridge loading

Bridges may have to carry several locomotives or wagons at the same time. especially on longer spans; in that case they require separate calculation of maximum allowable axle load. A weak bridge may limit the axle load of the full line.

Theodore Cooper Theodore Cooper (January 13, 1839 – August 24, 1919) was an American civil engineer. He may be best known as consulting engineer on the Quebec Bridge that collapsed in 1907. Biography Upon receiving a degree in civil engineering from Resselaer I ...

developed the E10 loading system for calculating the strength of bridges.

Roadway use

The term axle load is also applicable to

truck A truck or lorry is a motor vehicle designed to transport freight, carry specialized payloads, or perform other utilitarian work. Trucks vary greatly in size, power, and configuration, but the vast majority feature body-on-frame construct ...

s, and this context is made more complex by some trucks having more than two wheels per axle. The axle load remains the same, but the load borne by the individual wheels is reduced by having more contact area (more wheels, larger tires, lower tire pressure) to distribute the load.

References

External links

Managing rail degradation on the Malmbanan
Thomas Nordmark and Dr Per-Olof Larsson-Kraik, ''

Railway Gazette International ''Railway Gazette International'' is a British monthly business magazine and news website covering the railway, metro, light rail and tram industries worldwide. Available by annual subscription, the magazine is read in over 140 countries by tran ...

'' June 2007. {{Authority control Rolling stock