High sided vehicle

Hi guys, I was wondering if there is a legal definition of what is a high sided vehicle.
The reason I ask is that I drive a standard 26 ton builders merchants truck , today the Erskine bridge was closed to high sided vehicles.
As the wind wasn’t bad at the time I went over it as I wouldn’t consider my hiab dropside truck to be high sided.

So was wondering if anyone knows what legally constitutes one.
Duncan

Anything over 2.9mtr is classed as high sided.

Think it’s on the .gov website somewhere…

If your height is more than the width of what ever your driving then your classed as a high sider.That is what i was told by a copper and thats how they catch van drivers out.

Thanks for replys so far does height include the cab?
Duncan

It appears to be a judgement call. If bridge staff or plod say no then it’s no.

theforthbridges.org/plan-yo … d-weather/