Hi Guys,
Can someone please tell me what is the spacing between the short marker posts down the nearside edge of UK motorways. Are they all the same, or was there some \'metrication\' at some date?
I\'d like to do a spot of speedometer calibration with a stopwatch, and there isn\'t a \'measured mile\' for, well, miles!!
Cheers.
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weeeeeeell They are every 100 metres, numbered xxx/0 xxx/1 etc
Or they should be, but when this came up before someone who did motorway maint work said they just banged em in any old how.
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Renault Family may be referring to my comments from a couple of weeks back regarding these posts. I used to replace these posts and I'd say that the chances of you finding them being accurately spaced is minimal.
The posts are supposed to be spaced at 100metre intervals from the beginning of the motorway to the end. They are marked as such with the km's from beginning shown in white lettering on a blue background at the top of each post. e.g. 20km post would read 200, the next would be 201 the 1 representing the 100 metres travelled, up to 209 then to 210 to represent 21km and the sequence continues.
The problem with these posts in practice is that they are measured accurately when they are originally installed, i.e. when the mororway is new, but when they are replaced for whatever reason they don't tend to be remeasured with any accuracy.
When I replaced them it was easy if the post to be changed was still in situ, it would be a straight swop, but if the post was missing and the socket couldn't be located the next best thing to do would be to find the corresponding one on the opposite carriageway and try to position the new post as accurately as possible directly opposite. Doesn't always work like that and a lot of the time it's foot paces and guesswork I'm afraid.
Traffic Management teams use these posts as markers when laying out lane closures, this is not a commonly known fact as we all know that motorway roadworks boards show the distance remaining in yards whereas in fact the signs that show these distances are set out next to posts measured in metres!
Unfortunately the same TM teams are often guilty of damaging and flattening the posts when they put on or take a closure off.
Police tend to use the SOS box numbers for locations as they are relective, these numbers do tie in with the surrounding marker posts, but the marker post numbers aren't reflective.
Well I've waffled a bit, I hope it makes sense and sheds some light on the issue.
PP
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PP
Somehow I cannot visualise Highways have removed all the old posts and reset at 100metres when mileages are shown on signs.
My days the posts used to be set at half furlong with 16 to the mile.
Check it out, spot the mile post and note your odometer. Then
count 16 off which should co-incide with a further mile on the odometer.
DVD
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Given the likely innacuracies in timing etc, and that you are going to use 20 or so posts the fact that 1 or 2 are not in the right place is not really going to matter all that much. If you do several timed runs against different posts you should get a good idea how accurate your speedo is. The most difficult part is finding a piece of M-way that is quiet enought to stick to 75mph for 2 km (a nice easy figure as that is 120km/hr - will easily let you know if your reading under or over).
Even better still is beg/borrow/steal a GPS and use that instead!
Richard
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Lost me there DVD, I think you've misread my post.
My comment about roadworks signs was that they are set out to metres but show yards.
PP
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DVD - at the very best your check can be accurate to only ± 4%, as an odometer only records to 0.1 mile. In other words it will show 445.2 or 445.3, but you want it to show 445.272 to draw any conclusion. You have to measure about 20 miles (preferably more) in which distance a 30-yard error in a post at either end is relaively insignificant.
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I have to say that yet to find a better method then mine.
1) Find a friendly traffic plod. (not at all difficult in my ever so humble experience)
2) Explain the purpose of your mission and ask for the location of the measured miles that they use at the beginning and end of their shifts, and what are the marker points they use.
3) Note guilty expression that they had forgotten so far today. (apologies to you know who ;-)
4) Visit location at a time when traffic is quiet accompanied by an observer / time keeper in your car and make a few timed runs.
5) Plot a calibration curve
6) Make a timing run as a check every so often.
7) Robert is your father's brother.
Boring and worthy of a golden anorak award I know but frankly don't care, yah boo sucks.
Tried sat nav and it worked fine in the missus' Fabia, but a total non starter in Mondeo due to the heated screen messing about with the signal or so we thought.
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Good idea, FiF. But it will only be of use to calibrate the speedo, not the odometer, which as I said above, doesn't show enough sig.figs to reveal any but huge errors - unless you check over a long distance to make the figs. more sig.
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So we want to be perfect?
What about the rolling road at Crypton testing Centres?
For inf of Fif on his northern runs, come back from Darlington on the A.167. Just before Northallerton on the nearside look for an obelisk celebrating the Battle of the Standard, next look up overhead lines = half mile. Next look up grey post with reflective top on nearside = 1 mile. Need I say more?
DVD
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