geebee45:
ROG:
Are there still trailers out there which legally have no plated weight on them?
If yes, does that go by the actual weight being towed?Yes, there are loads of ‘old’ home made trailers that don’t have plates on them.
Usually go on tyre load index as that would give a maximum authorised mass
Thanks - I did wonder how that worked
geebee45:
ROG:
Are there still trailers out there which legally have no plated weight on them?
If yes, does that go by the actual weight being towed?Yes, there are loads of ‘old’ home made trailers that don’t have plates on them.
Usually go on tyre load index as that would give a maximum authorised mass
Quite unrelated but when you are on the prowl, 
sorry I mean undertaking roadside inspections with fellow officers. How would you check weigh a builders van with a trailer or a caravan as a public plate bridge in a quarry has probably got more aggregate on it than the builders van has in it.
I just wondered about the accuracy.
Public Weighbridges are checked for accuracy at least every 12 months by Trading Standards Officers. They can inspect at any time if they think something is amiss, bit like a scaled up version of them checking the scales at ASDA, Tesco or any other shop selling goods by weight.
VOSA bridges are checked every 6 months.
Part of the weighing process is for the ‘bridge’ to go through a ‘self-check’ and a ‘calibration’ process, during that process the ‘bridge’ measures any weight that is on it and then zeros, so it only measures the weight of anything subsequently added to it.
The above only applies to electronic ‘load cell’ bridges. If it is an old 'mechanical beam bridge (have only seen those in two places; Sicily and Apley Head) then you have to get the broom out and sweep the ‘plate’ if anything is dropped on it before weighing a vehicle
i remember once watching a program where a large lady had to be weighed on the local weigh bridge as the scales in the hospital didn’t go high enough so the resolution must be pretty good!
Also pretty embarassing for her as i seem to remember her sat on a chair in the middle with people queueing to use the bridge 
On a more serious note I guess they have to be pretty accurate as they use them for billing for aggregate etc.