The northbound A3 on the way into this junction is horrible. After the magnificent Esher Bypass, you are greeted by a 20mph limit drop, speed cameras and the road narrowing to 2 lanes, not to mention the A309 joining in while there are still only two lanes. This leads to huge queues, that sometimes even stretch back to Esher Common. The solution is to demolish the A309 slip road that joins before the underpass, and replace it with a slip road from the A3 to the Ace of Spades roundabout, which the A309 merges with before the roundabout. This would also solve the problem with the entrance into Kingston. Sadly, I don't think anything can be done about the lane drop, apart from the speed limit drop being less drastic. As for the way out of Kingston southbound, there is plenty of space to build a slip road onto the A3.