The Clevedon Interchange, junction 20 of the M5, is one of the largest roundabout interchanges on the motorway. It is at least as big as Gordano Interchange to the north and St Georges Interchange to the south, despite appearing to carry far less traffic. Making it seem even larger is the fact that there is only one other road joining the junction - the B3133 spur into Clevedon itself. Of course, there is a reason behind this huge roundabout, and that reason is, as can be seen below, the once proposed but long forgotten South Bristol Spur. Intended to cross North Somerset and use the Long Ashton Bypass on the A370 to enter Bristol from the south, the road was never built. However, this roundabout was created in anticipation of the road.
In more recent years, proposals for making use of this roundabout have ranged from a new South Bristol Motorway, which would have roughly followed the A4174 line to the M4 to the much more simple plan for a link road into Nailsea bypassing the B3130 through Tickenham. How serious, or offical any of these proposals have been is uncertain, but perhaps one day this enormous roundabout will finally get another road!