Network length (transport)

In transport terminology, network length (or, less often, system length) refers to the total length of a transport network, and commonly also refers to the length of any fixed infrastructure associated with the network.

A measurement can be made of the network length of various different modes of transport, including rail, bus, road and air. The measurement may focus on one of a number of specific characteristics, such as route length, line length or track length.

Continental European and Scandinavian transport network analysts and planners have long had a professional practice of using the following terminology (in their own languages) to draw a distinction between:

In 2000, this terminology was adopted by an English language best practice guide to public transport, to minimise the risk of confusion. Since then, a number of other English language specialist publications have adopted the same terminology, for the same reason. The terminology is therefore also used in this article.

The route length of a transport network is the sum of the lengths of all routes in the network, such as railways, road sections or air sectors. The U.S. Department of Transportation's Federal Transit Administration has also referred to this as "Directional Route Miles (DRM)". Where a network is made up of railways, route length has also been defined, by at least one source, as the sum of the distances (in kilometres) between the midpoints of all stations on the network.

In a measurement of route length, each route is counted only once, regardless of how many lines pass over it, and regardless of whether it is single track or multi track, single carriageway or dual carriageway.

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