Motorway

A motorway (in the United Kingdom, Ireland, New Zealand and some Commonwealth nations) is both a type of road and a classification. Motorways may also be regarded as highways designed to carry a large volume of traffic where a normal road would not suffice or would be unsafe, usually between cities. In the UK they are predominantly dual-carriageway roads, usually with three lanes in each direction although four-lane and two-lane carriageways are also common, and all have grade-separated access.

Inheritance

In the UK, certain types of traffic are not permitted on motorways. Thus, to avoid people being forced to travel illegally, there are a number of rules about stretches of road which must be designated as motorways.

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In all cases, there must be an escape route for traffic not wishing or not permitted to enter the motorway. As a result, the motorway technically begins as soon as the escape route has diverged from it; for example at a grade-separated junction, the motorway starts at the junction with the exiting slip road, and the opposite slip road is also part of the motorway for this and the following reason.

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As a result, this creates a less-restrictive set of rules for the standard of the road. Roads whose only destination is a motorway must be assigned motorway status, notwithstanding the possibility of them not being built to normal motorway standards. For example, the A48(M) motorway outside Cardiff begins after the last exit to St Mellons, since by staying on the dual carriageway you cannot get anywhere other than the M4 eastbound; however, the A48(M) is a motorway-grade highway. On the other hand, there are roads such as the A6144(M), a 1.2 mi (2 km) long single-carriageway road, which are classified as such since they lead inescapably to the motorway (in this case, the M60).

Related Topics:
A48(M) motorway - St Mellons - M4 - A6144(M) - M60

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