B doubles, as we call them are big over here, 26 metre (overall length) ones even doing local work. We also have 19 metre (pocket B doubles), mostly on local fuel tanker and tipper work.
What impresses me is the way the drivers can reverse them. Where I work, they reverse coupled up, onto a loading door, break them up and put the lead trailer onto another door.
To get them onto the door in the first place, they have to come in from a 90 degree angle as there is not enough room to reverse straight in. The same goes for re-coupling; the driver has to get the lead trailer to line up, coming in from the 90 degree`s before going under the skid plate.
As dirty Harry once said "a man has to know his limitations", that`s why I have stuck with single trailers.