Traffic light cameras and long vehicles

cxx666

Can someone please explain to me how the cameras that sense when a vehicle has gone through a red light work? I've read various things online and my head is all messed up now.

Basically I was approaching a junction in a bus, lights were at amber but if I stopped then I would have tipped it on its end and everyone would have gone flying, the front half of the vehicle went through on amber but before it had got past the camera fully the lights had gone to red. My understanding is that the camera goes live 1 second after the light changes to red. I've been past that junction god knows how many times this week and I've tried to gauge whether the back wheels had cleared the sensor before the light changed, but obviously thats not particularly easy to try and judge from looking in the mirror.

I had a similar incident during my training and my instructor told me not to worry as the light was amber as I began to go through, however I read online quite a lot that if any part of the vehicle goes over the line when the lights are red than an offence has been committed. I don't understand how that can be the case though, particularly in cases of long vehicles, surely the front wheels would need to pass the stop line on red as well as the back rather than just the back?

Is it all done automatically by computer or does someone actually look at the picture to decide if an offence has been committed?

Normally I'm fine and its not something I'm in the habbit of doing, but sometimes when I see I'm approaching a junction with a camera on it I start to panic and I think thats why it happened.

crazyguy

here: http://www.speedcamerasuk.com/traffic-light-camera.htm

cxx666

Thanks, I've read that already though. I should probably explain I do have an understanding of how they work, my confusion is more based around whether the whole vehicle has to pass through red in order for it to be an offence, as half my bus was already past the camera and into the junction when the light turned to red.

forgotmyname

Amber means STOP.

Having a long vehicle gives you a chance of appeal though as you can say you and the front half
passed the light on green, And you dont know who was driving tha back half.

vax2002

A lot have had the Amber light shortened and a few brave ones have won in court with timed video evidence showing the incorrect amber light duration.

George_Michael

forgotmyname wrote: »

Amber means STOP.

Unless you are too close to the light to be able to stop safely without crossing the stop line.
In this instance you are permitted to continue through the amber light.
(although in this instance there is the possibility that you could be prosecuted for other offences if it was thought that you were driving too fast for the conditions, driving without due care etc).

slyracoon

The cameras won't become active until after the red light has illuminated. They also work by sensors so if you have crossed the line but the vechile is stationary before the camera becomes active you should be fine.

flyingscotno1

OP, you should be fine. The cameras work by induction loop. Put simply when the red light is lit a current runs through them and when something metal travels over them the current is effected and changes. There are 2 loops one before the stop line and one after. They only work when the red light is lit, but I am of the belief they only work when the first is activated then the second. If both are activated at the same time you should be ok.

vax2002 wrote: »

A lot have had the Amber light shortened and a few brave ones have won in court with timed video evidence showing the incorrect amber light duration.

Got any links to this? I'd strongly disagree with 'a lot' being shortened. May have 1 or 2 but not common as nobody should be shortening amber times they are fixed 3 seconds, all the time, every time and there is no benefit to any engineer in shortening these.

cxx666

forgotmyname wrote: »

Amber means STOP.

Having a long vehicle gives you a chance of appeal though as you can say you and the front half
passed the light on green, And you dont know who was driving tha back half.

I very much doubt that would work as a defence. Oh, and I know amber also means stop, but as others have said, only if its safe to do so, and I didn't consider it to be on this occassion.

slyracoon wrote: »

if you have crossed the line but the vechile is stationary before the camera becomes active you should be fine.

I wasn't stationary though, I was well into the junction as the red light changed so I thought it safer to carry on than block the junction and/or cause an accident by braking hard.

flyingscotno1 wrote: »

There are 2 loops one before the stop line and one after. They only work when the red light is lit, but I am of the belief they only work when the first is activated then the second. If both are activated at the same time you should be ok.

How do you mean if they are both activated at the same time? Surely the first would have to be activated before the second every time as something passed over the sensors?

DaveF327

cxx666 wrote: »

its not something I'm in the habbit of doing, but sometimes when I see I'm approaching a junction with a camera on it I start to panic and I think thats why it happened.

Just a suggestion... rather than panic, you can help yourself and your passengers by losing just a tad more speed while approaching the light on green.

I've seen bus drivers chancing the lights a lot and in a lot of cases, they actually would have had plenty of time to stop without sending people flying had they not been thundering up to the light at 34mph. I'm not saying you do this, but it's an observation i've made. I had a similar comment from a young driver who used to chance the lights on a 50mph dual carriageway. Once I showed him how to anticipate, ease off to around 40 covering the brake, then accelerate once past the point of no return, he found it so much easier on one occasion when amber showed at the worst possible moment. A safe controlled stop was felt by all, and there was no concern of a camera flash.

cxx666

DaveF327 wrote: »

Just a suggestion... rather than panic, you can help yourself and your passengers by losing just a tad more speed while approaching the light on green.

I do this yes, however I've been driving them less than 2 months so still gaining experience "on service" with passengers. I'm not making excuses for what happened, other than that in my opinion it wasn't safe to try and bring it to a halt when I saw the amber light.

I've contacted my local camera office to enquire as to whether the length of a vehicle is taken into account when this type of situtation occurs, as my front wheels definitly crossed before the red appeared but the back ones I'm not sure about.