At the begining of August I spent 2 hours crawling from the Longlette turn off to almost Sailsbury 1st and 2nd gear all the way, the journey that I was doing noramly takes 2 to 3 hours if I stop for a break, that Saturday it took us almost 5 hours....
But I do find that Hampshire and Wiltshire do give the motorist a chance at least, in many areas they flash a warning if you enter the speed limit too fast to remind you and if you don't heed they nab you down the road with the camera, very fair I think.
Going into Sailbury there is a low Railway bridge, and this trip I noticed as well has the normal height warning signs, they have now implemented a electronic measuring system that detects high vericles, and flashes them a warning that they must slow down, and they need to be in the middle of the road to enable them to pass under the bridge, and I assume that if there vericle is too high they get told to stop!
When my parner and I go to Dover to visit family, we usually leave Langport in Somerset at about 5.00am, even the A303 is fairly quite then. we then return Sunday, traffic levels are not too bad even then, most times!