‘When can I wait in a yellow box junction‘ is a very common question from new drivers. There are some who think you cannot.
The purpose of a yellow box junction is to keep an area clear. So the basic rule is not to enter it unless you have a space clear at the other side.
You may wait within the box though if you are turning right; providing you are only waiting for a gap in the oncoming traffic before completing your turn (image 1).
If queuing traffic is blocking your exit however, you should not enter the box even if you are turning right (image 2).
How many cars can go into the yellow box?
There is no limit to the number of drivers who can wait in the box. But you do need to take into account how much space is available beyond the yellow markings. If queuing traffic means for instance that there is only enough space for a couple of cars at the exit, then you should hold back if there are two or more drivers ahead of you.
You also need to be aware that oncoming drivers who are turning left may also take up any vacant space (image 3); and this is where things become a little more complex. If you are in doubt then hold back. When the oncoming traffic clears or the lights change, you should not put yourself in a position where you cannot move off and clear the junction.
There are some busy junctions where a yellow box junction may have traffic sensors. If you get stuck in the middle here you could end up with a fine.
The trick is to keep your distance from drivers ahead when you are approaching any kind of junction. Open up some space so that you have a better view of the space available and more time to react. That way, the question of ‘when can I wait in a yellow box junction’ will be more easy to answer. And if the driver ahead misjudges it, you are less likely to get caught out yourself.