On
railways, a given section of tracks is designed to support a maximum axle load. The maximum
axle load is determined by train speeds,
weight of rails, density of
sleepers and fixtures, amount and standard of
ballast, 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 locomotives 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 locomotives were supplied by
CRRC 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 developed the
E10 loading system for calculating the strength of bridges. == Roadway use ==