Driver location signs

Driver location signs are signs placed every 500 metres (550 yd) along each side of English motorways, and some other major English roads, to provide information that will allow motorists to know their precise location. Only roads in England feature these signs; they are not found on roads in Scotland, Wales or Northern Ireland. This information might be useful in the event of an emergency or breakdown. They were first introduced in 2003, and they complement distance marker posts (small roadside posts used for road maintenance and administrative purposes). Both types of sign display a unique location number. The number, although given without units, is the distance in kilometres from a designated datum location for the road.

While the driver location signs are metric, other road signs throughout the UK use imperial measurements (miles and yards).

Since at least 1980, motorways have had distance marker posts installed at 100 metre intervals alongside the hard shoulder. These posts are used to help pinpoint road locations for maintenance and emergency purposes, and also show the direction to the nearest emergency roadside telephone. The numbers on the posts, for which no units are given, are derived from the distance, in kilometres, of the post from a reference datum location such as a city centre, an administrative boundary or some other feature. On the M25 for example, distances are referenced to a point near Junction 31 even though the section of the ring road between Junction 31 (post 186.6) and Junction 1a (post 5.7) is the A282, not the M25. On motorways distance marker posts also bear an arrow pointing towards the location of the nearest emergency telephone.

The number used on distance marker posts is also encoded into the numbers associated with motorway emergency roadside telephones. In this way motorway control centre staff can pinpoint the telephone from which a call is being made.

Items of highway furniture are commonly uniquely identified by a code number attached to or stencilled onto them. On motorways the number from the closest distance location marker is generally incorporated into such identifiers. They are also sent in the signal from traffic cameras to identify the location of the camera.

These signs give the same location information as distance marker posts, but more visibly on larger signs, which are generally placed at 500-metre (547-yard) intervals. If obstacles prevent signs from being spaced at 500-metre intervals, then the interval must be reduced to either 400 or 300 metres (437 or 328 yd). By the end of the 2009 financial year, 80 percent of England's motorway network had been fitted with 16,000 driver location signs at a cost of £5.9 million (about £570 each). It was expected that the remaining 20% of the motorway network would be covered by April 2010 at a cost of £1.6 million. As of July 2009^[update] driver location signs had not been erected in Scotland, Wales or Northern Ireland.

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