when nortbound on a470 out of bluith wells. paper map says 14ft satnav (truck) says 14ft tape measure says 14ft 2 bridge sign says 13 ft 8
WHY■■?/ 
not sure, think they might do it for a “just incase” sort of thing 
ive taken my lorry under a 12ft 6in bridge and my lorry is 12ft 7in, but then the exact same lorry and it says its 12ft 8in.
I actually dont think thy no what height they build these lorrys 
In Exeter, i used to put a 10ft 9inch truck under a 10ft 3inch bridgeand still had 3 inch to spare.
You need some clearance, 6" seems fair enough to me.
I wouldn’t want to take a trailer, measured at 14’2" under a bridge measured at 14’2".
What if there was a slight dip in the road which made your trailer bounce up ■■
I pull a Euro-liner, at a standstill it measures 4.0m tall. When I’m moving the air moving over the top ■■■■■ my canvas roof up at the front several inches. If there was no clearance my roof would need repairing every time I went under a 4.0m bridge.
You would also want some clearance to allow for a build up of snow, or a fresh layer of tarmac or …
As to why a bridge itself is signed as 13’8", but the map and sat-nav info had it as 14’2", I’ve no idea really. I would guess that a mapping company hired a firm of specialists to measure the clearance of all bridges. The firm measured them and reported their measurements to the mapping company. The mapping company then printed out their maps with the measured heights and sold that info on to the Sat-Nav companies. So everyone is using the same measurements.
The council, who signed the bridge measured the height of the bridge, then knocked off 6" for extra clearance when they signed it.
This would be to allow for truck and bus drivers driving up to a bridge, properly signed as 13’8", in their 14’ vehicle and carrying on under it. Fine, because they allowed some extra clearance. Not so fine if the bridge had been struck because it really was 13’8" , and there was an inch of snow.
I by passed that bridge in Builth Wells the other week cos I was 13’9"…
Was going to chance it, wish I had now
At least I know for next time…
gezt:
when nortbound on a470 out of bluith wells. paper map says 14ft satnav (truck) says 14ft tape measure says 14ft 2 bridge sign says 13 ft 8WHY■■?/
i have just looked at my map and and on the map the bridge is 13.6f there is a 14.00f but that one is to the left on an other road
triangle-advised so you can add a couple of inches. red circle- don’t risk it! add six inches to every bridge simon and you would be buggered on my job!
Surely all bridges could be made 16"6 by planing a bit off the roads approaching them, pay enough road tax for it
A lot can be, some can’t be though. Depends on their foundations. It’s not unknown for bridges and tunnels to collapse when this job is being done. Also, you’ll have to shave off the road 40ft from the bridge too otherwise your arse end’ll be higher than the front and it’ll get you nicely wedged under the structure
Strange … I thought all men were accustomed to those sort of er erm inaccurate/dodgy measurements??
I have taken 138" under 136" with room…But what is it about drivers who think that you can move over under an arched bridge…They get terribly vocal when you don`t move over…Not as vocal as me in ■■■■■■ mode though 
truckermarcus:
triangle-advised so you can add a couple of inches. red circle- don’t risk it! add six inches to every bridge simon and you would be buggered on my job!
And your job is ?
mmmmm
truckermarcus you need to re evaluate your thinking
a triangle sign that says 4.2 metres that means the bridge is 4.2 metres
a round sign that says 4.2 metres that means vehicles over 4.2 cant go but running at 4.2 you can
not that i have any faith in UK bridge signage
Out off curiosity IF you hit a bridge marked say 13’9" with your cab/trailer that is say 14" who pays?
if its marked up with enough clearance an i right in assumming the council would need to pay out(ins) as its wrongly marked up or is it the drivers responibility to assume they are all wrong and check■■?
the driver who watched me thru said all their timber wagons (local firm) are 14 ft and they all go under with room to spare. they have measured the bridge with a tape and its actually 14ft 4 inches. is seems the bridge owners (railtrack)asked the height to be signed lower.
dont know why they did that
i have been under that bridge many times with a 13ft 9 trailor when it was signed as 14ft so why then change when nothing has altered.
and according to my map book it is on the a470 and there is no other bridge near so that maybe wrong as well