Driver location signs are small blue signs on all motorways and some major A-roads in England and the Republic of Ireland (where they're called Location Reference Indicators). They're used by emergency services and breakdown teams to find accidents and stranded vehicles.

WHY WERE DRIVER LOCATION SIGNS INTRODUCED?

Traditionally, roadside emergencies and incidents were reported using the emergency roadside telephone (ERT) system. These SOS phones are positioned every 1 mile (1.6 kilometres) on all motorways and selected major A-roads with a direct line to traffic control centres or police control rooms. They also provide a specific location of where the call is coming from.

However, with the development of mobile phone technology, majority of people started reporting emergencies and incidents using their own device rather than an ERT. Although there are marker posts every 100 metres to help pinpoint road locations, they aren't particularly visible unless you're out of the vehicle on a busy and dangerous road.

The need for more visible roadside location information was evident from an incident reported by the Devon and Somerset Fire & Rescue Service in 2007. After a serious collision on the M5, their control centre was inundated with calls from concerned drivers using their mobile phones. The locations given to operators stretched over 40 miles (64 kilometres), causing four emergency centres to be mobilised instead of one.

Mobile phones aren't the only culprit with a large percentage of drivers using navigation aids such as sat navs or Google Maps to get to an unfamiliar destination. While undoubtedly helpful, it often leaves people not knowing where they are in their journey. Gary Baldwin, a 30 year veteran of Thames Valley Police's Forensic Collision Investigation Unit, said that "half of people don't know whether they're going north or south, which junctions they're between or even which motorway they're on".

WHEN DID DRIVER LOCATION SIGNS FIRST APPEAR ON UK ROADS?

Before rolling driver location signs out across all motorways, they were trialled on parts of the M25 and M6 from 2003. These experiments helped to improve emergency service response times by 10%.

From 2007, a programme to erect driver location signs on England's motorways and major A-roads commenced. By the end of the 2009 financial year, 80% of England's motorway network had been fitted with 16,000 driver location signs, with the remaining 20% completed the following year.

WHERE ARE DRIVER LOCATION SIGNS AND WHAT INFORMATION DO THEY PROVIDE?

Driver location signs are found on all motorways and slip roads in England, as well as some major A-roads, adjacent to the distance marker post. Generally, they're placed every 500 metres; however, if obstacles prevent the signs from being spaced at this distance, it is reduced to either 400 or 300 metres.

They are never placed in the central reservation or on the off-side of a slip road. Despite being small, the yellow font on the blue background is prominent and legible enough to be read from a considerable distance, such as a passing vehicle.

Every driver location sign provides the following information to make it easy to find the caller's location:

  • The road the driver is on
  • The direction the driver is travelling
  • How far the driver is from a given location

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HOW TO UNDERSTAND THE INFORMATION ON A DRIVER LOCATION SIGN

Driver location signs are split into three rows giving the above information and a complete breakdown of where on the road you are.

LINE 1: THE ROAD THE DRIVER IS ON

For example, M4 or A4.

LINE 2: THE DIRECTION THE DRIVER IS TRAVELLING

This identifies the carriageway you're on and is typically either 'A' or 'B'. In the simplest of terms, 'A' carriageways are those heading away from London (or clockwise in the case of the M25 and M60) where the junction numbers count up. 'B' carriageways are those heading back to London (or anti-clockwise in the case of the M25 and M60) where the junction numbers count down.

Any adjacent service roads, secondary carriageways, collector or distributor roads are identified as 'C' (adjacent to the 'A' carriageway) or 'D' (adjacent to the 'B' carriageway).

Slip roads, link roads and emergency access connections are identified using 'J', 'K', 'L' and 'M':

J - exit slip road from the 'A' carriageway

K - entry slip road from the 'A' carriageway

L - exit slip road from the 'B' carriageway

M - entry slip road from the 'B' carriageway

LINE 3: HOW FAR THE DRIVER IS FROM A GIVEN LOCATION

This is identical to the location given on the distance market posts. It shows the distance in kilometers from a known datum point - typically the start of the road. As majority of the signs are placed every 500 metres, the numbers tend to count up or down in intervals of .5.

This is arguably the most important figure because it pinpoints the location on a road that could span over 200 miles.

TIPS FOR USING DRIVER LOCATION SIGNS

Driver location signs are designed to help locate vehicles that have broken down or been involved in a road traffic incident. Always ensure you use a hands-free device or pull over somewhere safe to inform the emergency services or breakdown cover of the location marker information.

Only ever give the marker location on your side of the carriageway, otherwise the emergency services or breakdown provider will be on the wrong side of the road and it will take them longer to get to your location.

If you're reporting an incident you witnessed and have since driven passed, try to remember the bottom number of the nearest location marker as the top two will generally remain unchanged.