Mileage/kilometerage posts

The message from snipped-for-privacy@ubht.swest.nhs.uk (Malc) contains these words:

They're 100m posts. The 57/1, 57/2 etc is kilometers and tenths of kilometers from the start of the motorway.

There are mile posts, but they're rare. You're looking for a disc the size of a dinnerplate. The first one is solid one colour - blue, I think. The next has a white quadrant, the next a white half the next is

Personally I use the 100m posts over a few minutes and do the maths - it's easier, less distracting, easier to find and has the potential for greater accuracy.

Don't forget you have to pass 11 posts to make a kilometer.

And errors in the speedo, which will be over-reading.

The ones I remember were red, there used to be a full set on tha A41 between the M40 and Bicester, nice stretch of straight road that. I've not seen any of the mile ones for ages; at least not a full set of 4. I think they were specifically put up for "calibrating" speedos in police car's?

Will

The message from "Will Reeve" contains these words:

They're getting thin on the ground - I imagine they're obsolete.

Well yes that's kind of what I was assuming. It's not easy using the digital clock in the dash to time yourself (wait for the minutes to change then look for the next post), count posts and keep a constant speed in fairly heavy traffic. So the result is close enough to tell me I was making the right assumptions. If I want real accuracy I'll take a stopwatch monkey with me.

The message from snipped-for-privacy@ubht.swest.nhs.uk (Malc) contains these words:

Sod that - I employ a small boy to do it for me.

A GPS is a lot easier!

The message from "Mark W" contains these words:

But not necessarily as accurate.

You cannot calibrate speedo's in this manner. Calibration dictates you use equipment 10 times more accurate than the equipment you wish to check. Example if your speedo has graduation of 1 mph then you must calibrated against something that is accurate to 0.1 mph and traceable to National Physics Lab.

Fatsod

I've also seen barcoded signs strapped to lampposts. Theses are about

-- Chris

I *think* they are used by road survey teams... They have some doobery that scans the road and someone scans the barcode so it where it is

That could all be rubbish... But it sounds vaguely familiar!

The message from Chris Lawson contains these words:

No - I've wondered that. I've also noticed that the barcode is done in reflective stripes against white.

I suspect that's why he put calibrating in quotes. We're only really talking about checking speedos here. I think we all appreciate that we haven't got the kit to really calibrate the speedo.

If you can afford one and have the use for one. Personally I rarely get lost so I have no need for a GPS.

Council lampost sale! :))

Pete

And the road survey barcodes went up around 15 years ago, when the only people who had GPS were the US Military...

A lot seem to have fallen into disrepair now, so I wonder if the system has been superseded by a GPS related one.

Rich.

They are for busses to read - in part of London (and elsewhere) they are putting electronic displays at bus-stops that tell you what bus is coming and how long you will have to wait.

The busses have a barcode reader on the top-deck that contacts the control centre each time it sees a bar code. The system then works out where the bus is and updates the bus-stop displays.