United Kingdom In the United Kingdom, the chain is no longer used for practical survey work. However, it is still used on the railways as a location identifier. When railways were designed, the location of features such as bridges and stations was indicated by a cumulative longitudinal "mileage", using miles and chains, from a zero point at the origin or headquarters of the railway, or the originating junction of a new branch line. Since railways are linear in topology, the "mileage" or "chainage" is sufficient to identify a place uniquely on any given route. Thus, a given bridge location may be indicated as 112 miles and 63 chains (181.51 km) from the origin. In the case of the photograph, the bridge is near
Keynsham, which is that distance from
London Paddington station. The indication "MLN" after the mileage is the
Engineer's Line Reference describing the route as the
Great Western Main Line, which is needed to uniquely determine the bridge, as there may be points at 112 miles 63 chains on other routes. On new railway lines built in the United Kingdom such as
High Speed 1, the position along the alignment is still referred to as "chainage", although the value is now expressed in metres.
North America The use of the chain was mandatory in laying out US townships. The unit was also used in mapping the United States along train routes in the 19th century.
Railroads in the United States have long since used
decimal fractions of a mile. Some subways such as the
New York City Subway and the
Washington Metro were designed with and continue with a
chaining system using the 100-foot
engineer's chain. In the United States, the chain is also used as the measure of the rate of spread of wildfires (chains per hour), both in the predictive
National Fire Danger Rating System as well as in after-action reports. The term
chain is used by wildland firefighters in day-to-day operations as a unit of distance.
Australia and New Zealand In
Australia and
New Zealand, most building lots in the past were a quarter of an acre, measuring one chain by two and a half chains, and other lots would be multiples or fractions of a chain. The street
frontages of many houses in these countries are one chain wide—roads were almost always wide in urban areas, and roads were local roads in farming communities. Roads named Three Chain Road etc. persist today. The "Queen's Chain" is a concept that has long existed in New Zealand, of a strip of public land, usually 20 metres (or one chain in pre-metric measure) wide from the high water mark, that has been set aside for public use along the coast, around many lakes, and along all or part of many rivers. These strips exist in various forms (including road reserves, esplanade reserves, esplanade strips, marginal strips and reserves of various types) but not as extensively and consistently as is often assumed.
Cricket pitches The chain also survives as the length of a
cricket pitch, being the distance between the stumps. ==Measuring instruments==