Manchester Airport (Terminal 1).
From the M56 link road, there are two lanes into the car park at Terminal 1. That's the pink line on this map. One lane goes into the drop-off point and the other into the main car park. Great idea. At least it was, until some wally decided to merge the two lanes right at the car park entrance, where a third lane joins (the grey line).
So, you have three lanes, all merging into a single lane within 25 yards of the entrance to the car park,and to make it even better, there are absolutely no signs anywhere on the two-lane slip road which tells you that this is going to happen, until you get to the end and see the white arrow painted on the road surface. The resulting single lane then gives you the option of taking the left-hand entrance to the drop-off point or the right-hand entrance to the car park. Genius!
Surely it would be far more sensible to mark the left lane as being for the drop-off point and the right lane for the car park (seeing as there are two separate entrances) and then you don't need merge the two lanes at all. Oh, sorry, that would be the sensible thing to do, wouldn't it?