Traffic lights and box junctions

Supersonos

At a box junction, there is usually a gap of about 1 or 2 car lengths from the stop line to the box.

So if the light is green and you pass through the stop line, but then don't enter the box because your exit isn't clear, what should you do if the light goes red and your exit then clears?  I'm over the stop line, so the red light no longer applies to me, correct?  So can I continue across (assuming it's clear)?

AdrianC

Simples. Don't cross the line until your exit is clear.

But, if for some reason you must, then you should wait, so long as you aren't obstructing any pedestrian crossings or other traffic. If you are, then make a decision whether it's safer to wait or continue.

Supersonos

AdrianC said:

Simples. Don't cross the line until your exit is clear.

So why doesn't the yellow box start immediately after the stop line?  Why have a couple of car lengths?

facade

Supersonos said:

At a box junction, there is usually a gap of about 1 or 2 car lengths from the stop line to the box.

So if the light is green and you pass through the stop line, but then don't enter the box because your exit isn't clear, what should you do if the light goes red and your exit then clears?  I'm over the stop line, so the red light no longer applies to me, correct?  So can I continue across (assuming it's clear)?

Provided every teenie weenie bit of your car, including the towball is forward of the stop line, then correct, you are not bound by the stop light.

However, there will likely be a pile-up if you cross when the lights facing you are red, and although they won't be able to prosecute you for crossing the stop line on red, they will for some variant of careless driving.

No-one reads the bit about green meaning "proceed- if it is safe to do so"  and crossing traffic will be busy smoking their tyres setting off and won't be expecting you to start moving, as usually everyone gives up and stays still when the lights are red and they are between the stop line and the junction (making it difficult for lorries to turn in.....)

Plus all the witnesses will swear blind you went through a red light, they won't be considering which side of the line you were.

AdrianC

Supersonos said:

AdrianC said:

Simples. Don't cross the line until your exit is clear.

So why doesn't the yellow box start immediately after the stop line?  Why have a couple of car lengths?

There's "it's a stupid thing to do", and there's "it is illegal to do".
Wise people don't necessarily need things to be illegal to know not to do them.

Supersonos

These replies still aren't really answering the question.

Stop line - do not cross on red.
Box junction - do not enter if exit is not clear.

But there have been occasions that I've crossed the line and can no longer even see the lights, and then later the exit to the box clears.  By the rules of the road, I can then enter the box (if it's safe to do so).

Why doesn't the box start immediately after the line?

There's a junction in Hammersmith where there is room for about three cars after the lights, then a box junction.  Who gives way to who?

https://www.instantstreetview.com/@51.491337,-0.223242,287.75h,-12.19p,1z

AdrianC

Supersonos said:

These replies still aren't really answering the question.

Oh, they do...

But there have been occasions that I've crossed the line

...despite knowing that you can't clear the junction...

That bit is the bit you simply don't do, assuming your brain isn't in neutral and you aren't blithely following the back bumper of the car in front.

There's a junction in Hammersmith where there is room for about three cars after the lights, then a box junction. Who gives way to who?

Not an issue, unless you cocked up and entered the junction (as a whole) while it wasn't clear to exit.

Let's see a streetview link...

Supersonos

AdrianC said:

Let's see a streetview link...

Posted.

Supersonos

AdrianC said:

Supersonos said:

These replies still aren't really answering the question.

Oh, they do...

But there have been occasions that I've crossed the line

...despite knowing that you can't clear the junction...

That bit is the bit you simply don't do, assuming your brain isn't in neutral and you aren't blithely following the back bumper of the car in front.

There's a junction in Hammersmith where there is room for about three cars after the lights, then a box junction. Who gives way to who?

Not an issue, unless you cocked up and entered the junction (as a whole) while it wasn't clear to exit.

Let's see a streetview link...

So if you simply don't do it, why is there a gap between stop line and box junction?  I always assumed it was to increase flow - to get cars through the lights even though they couldn't fully proceed, but the more I think about it, the more that doesn't make sense.

AdrianC

Given that link, if you stay in the unboxed area, you aren't in anybody's way. 

And quite why you can't see that traffic light at the end of the island on the left, next to the rear door of the black car that's just entering the box junction, I have no idea... But, again, assuming you were actually aware of your surroundings on crossing the line, it's a non-issue. Or, to put it another way, it's only an issue if it's one totally of your own making.

DoaM

For that particular junction I would interpret the box itself as a secondary stop line, the clue being that there is a traffic light next to it. So if that light is on red you do not proceed.

And as above - if you can't see that light then perhaps an eye test is in order. If you're moving then you should be able to see it on approach to the box - if you're stopped then you should still be able to see it, even if you have to crouch down to be able to see it from the driver's seat.