Anybody else noticed those barcodes on main roads?

[ralph1953]

What are (or were) they for? They're about 2 feet high by 1 foot wide with the bars horizontal, facing the carriageway. I've seen some lately on the M5, at the back of the '1 Mile' signs for Junctions 11 and 5 , southbound. I seem to remember seeing them on other roads some time ago. I'd guess they aren't used for anything now cos they're rather faded and if they are barcodes, would be difficult to scan. Any ideas?

[sft42]

As far as i can tell these are use by traffic cops to help judge speeding traffic more easily (if it's the things i'm thinking of).

[ralph1953]

Hi sft42! Are you thinking of the white lines across the road at speed cameras? The "barcodes" I mean are on metal plates, about 6 feet above the road, facing the carriageway: and all the ones I've seen lately are tucked away behind other, larger signs. Spotted two more today, either side of Wooley Edge Services on the M1; northbound, 2/3mile before J39; southbound, 1mile before J38. They're easier to see from the other carriageway as they're at the back of some quite large signs.

[xyzzyplugh]

I seen these before - 10 years ago. Huge barcodes; I guess so they can be scanned by a helicopter. My guess is that they contain road info, like underground utilities and stuff but I could be so wrong..

[ralph1953]

Phew - got on at last! I promise I didn't know the A when I posed the Q but I have found out - by calling The Highways Agency (07845 50 40 30) Apparently, these barcodes formed a network of reference points used by the Agency, between 1990 and 1999, when surveying the main roads and motorways. The vehicle would drive along and senors (and maybe manual input) would monitor the road surface (presumably with a view to repairs) and as they passed one of these signs would fix the location (Each sign had a unique number which corresponded with a map reference - I suppose that the speedo filled in the gaps) so that the dowloaded data could be fed to the mainframe. GPS has, of course, taken over the location situation so these barcodes are now redundant. Most of them were fixed to other, existing, signs and as these are renewed or moved, the barcodes are removed and not replaced. Don't miss the chance to take in a bit of industrial archeology: look out for one tomorrow. I've awarded myself 3 stars and position as Milk Monitor.