There's been a lot of funny blue signs cropping up lately - about every 500 metres in both directions along many English trunk roads. They are part of a Highways Agency scheme, trialled at first on the M6 in Cheshire, then the M25's southern section and the M42 east of Birmingham. Now they're going national.
For many years this was easily the most common question Roads.org.uk was asked: "what do the strange blue signs mean?".
Big brother, little brother
The signs are actually just a larger version of the marker posts that already exist down the side of all motorways and most trunk routes. It's surprising how few motorists realised these little markers existed until now — and what useful information is on them.
The markers are all numbered, and these digits form a unique reference that allows breakdown and emergency services to find you if you're stranded by the side of the road. The small markers also show the direction to the nearest emergency telephone.
How do they work?
The text on the new signs provides all the information the emergency, highway or breakdown services would require to pinpoint a motorist's exact location.
The number of the road you're travelling on.
- A, B or C
The carriageway — A is usually the side on which junction numbers count up, B is usually where they count down. On motorways radiating from London, A is 'Away' and B is 'Back' again. Other letters are used for sliproads — J, K, L and M are frequently used for simple interchanges with four slips.
The mileage (in kilometres) from the notional start point of the road. The signs appear every 500m, so numbers count up 300.0, 300.5, 301.0, 301.5 and so on. There are some sections of motorways where something is in the way of signs and it is easier to post them at .3 and .8 than .0 and .5.
Why were they created?
Increasingly drivers have mobile phones with them. This means first that, when drivers break down, they aren't using the emergency phone system. Emergency phones have the reference for their location shown clearly, and can be traced, but someone on a mobile phone could be anywhere.
There is apparently an increasing number of incidents where motorists are either calling from the roadside, or calling about an incident they have just passed, while still moving, but are unable to pinpoint their location (or, in some circumstances, give any indication of where they are at all).
The new signs are designed to be very prominent and legible to passing vehicles; the Highways Agency suggests that a passenger could call if there is anything to report while the vehicle is moving. They also leave no question about what road the driver is on or which carriageway — both of which have been difficult to ascertain before now.
With thanks to Mark Hampson, Mark, Jon Body, Martin Vlietstra, Chris Cowdery and Matthew Sparks for information on this page.