SWEDISH BLUE:
If it is less than 16’ 6", then it must be marked
It’s actually 16’ 3", reason being bridge heights go up in multiples of 3" and a 16’ 6" would not be marked and a 16’ 3" would be marked so an unmarked bridge could be 16’ 4" or 16’ 5"
Unless something has changed, very recently and very quietly, I have always understood the minimum height clearance of an unmarked structure to be 16’ 6" or 5.0m. That is, a vehicle up to 16’ 6" high will pass safely under such a structure.
A structure that admits a 16’ 6" vehicle to pass would not be marked up, but a structure that admits only a 16’ 5" or 16’ 4" vehicle would be marked - and it would be marked as 16’ 3", on the principle that the clearance is rounded down in the direction of safety.
An unmarked bridge could never properly have only 16’ 5" or 16’ 4" of clearance, since that would be a situation in which a bridge having less than 16’ 6" clearance was unmarked (when the rule is that an unmarked structure always has at least 16’ 6")!
Daytrunker:
There’s a bridge just out of Walsall towards the A5 marked 14ft and double decker buses fly under it and I’m sure buses are taller than 14ft
I go under there regularly and I’ve seen car transporters and double deckers go through. It’s marked up wrong but I don’t know the actual height in the centre.
cupidstunt:
Does anyone know why there is a bridge marked at 16’9" on the A50? Been wondering for years.
Because it’s close enough to 5.0m that it’s liable to get hit.
The railway bridge over the A96 at Huntly is also signed as 5.1m /16-9 and has an alternative route signed for high vehicles.
Bridges wouldn’t be built that low these days, it probably seemed like a good idea at the time to build them only just over the 5m limit, but it doesn’t give much leeway.
There was a bridge over the M9 that had to be rebuilt a few years ago as it kept getting hit, even though it was over 5m, but not by much.
Thought it was a bit strange when I saw it for the first time.
New overhead structures will often get signed, just because it’s something new, even though there is plenty of clearance.
When the new tolls were built at the Forth Road Bridge temporary signs with the height were there for a while, as there had not been anything overhead previously.
