There's a roundabout near me to access J17 on the M60. Approaching from the north there are 3 lanes:
- The left lane is for access to the eastbound M60/M62 only
- The middle lane takes you straight on to the southbound A56 through Prestwich
- The right lane can be used to go straight on or to access the anti-clockwise M60
- Once you're on the roundabout it's just two lanes, so the middle lane on the approach becomes the left lane.
If you go straight on there's a right turn for a Tesco store, Prestwich Hospital and other places. If you're going there you need to be in the right lane approaching the roundabout. There used to be a lot of confusion with traffic in the left lane on the approach wanted to go straight on, and cutting in when they realised, and I hated using that roundabout for that reason.
Bury Council helpfully put up signage making it clear which lane you needed to be in and also changed the road surface of that middle approach lane to a different colour, so all you had to do was follow that colour and you'd be safely in the left lane on the roundabout itself.
You'd have to be a complete moron to get it wrong but it's amazing how many still take that middle lane on the approach, ignore the clear road surface colour that takes them into the left lane and pull across into the right lane completely oblivious to all the signs.