Variable Speed Camera Delay

hellarda · 12 Mar 2019 at 10:38

Morning,

I was driving around the m25 this morning just before the A3 junction and went through that gantry that has the variable speed camera (just before Cobham services). All the gantries previous had been at 50mph so had cruise set to 50mph and all was good.

Literally as I drive under the gantry, I must have been 4/5m in front of it, the sign changed to 40mph. Seeing as I had someone right up my arse I didn't want to slam on the brakes and assumed I'd be fine as there would be a delay.

However as I went through the gantry the camera flashed 4/5 times (there were people in the same situation in other lanes).

So have I been done? I can't think of anyway to prove that the gantry changed as I went through it, and I really don't think I've done anything wrong?!

Hyburnate · 12 Mar 2019 at 10:40

I believe there's a delay of 10s, but where or who I heard that from I'm not sure.

200sols · 12 Mar 2019 at 10:42

Dashcam would prove it.

Scania · 12 Mar 2019 at 10:43

There is a delay, it’s a few seconds (barely 10 I’d say) I know this because I spent an hour sat by the side of the M25 last year with a blowout and I passed my time by watching the gantry signs change and then seeing the flashes of the cameras going off!

tom_e · 12 Mar 2019 at 10:46

Pretty sure the actual delay in whether the system issues you a ticket is much higher than the camera trigger, somewhere in my mind says it's at least 30 seconds.

Hyburnate · 12 Mar 2019 at 10:48

http://www.ukspeedtraps.co.uk/gatso10.htm

I've skim read the above, and in my mind if it flashes it's going to issue a ticket, unless it's out of film.

It reads to me like if the timer has expired etc etc then it goes live and power is provided to the camera.

IAmATeaf · 12 Mar 2019 at 11:09

There is no film these days is there, though it was all bits and bobs?

ci_newman · 12 Mar 2019 at 11:13

IAmATeaf said:
There is no film these days is there, though it was all bits and bobs?

Hyburnate said:
http://www.ukspeedtraps.co.uk/gatso10.htm

I've skim read the above, and in my mind if it flashes it's going to issue a ticket, unless it's out of film.

It reads to me like if the timer has expired etc etc then it goes live and power is provided to the camera.

Yeah, no film in the modern HADECS cameras on the M25.

Hyburnate · 12 Mar 2019 at 11:23

IAmATeaf said:
There is no film these days is there, though it was all bits and bobs?

ci_newman said:
Yeah, no film in the modern HADECS cameras on the M25.

In that case, I think we can safely disregard anything that website has to offer

e; website that seems to state the camera that is in use on the M25

https://www.speedcamerasuk.com/hadecs-3.htm

JW1993 · 12 Mar 2019 at 12:33

I'm fairly certain there's a 60 second grace period from when the gantry changes. I'm not sure about the M25 but in other locations I'm also pretty sure there are cameras before that gantry that capture what the gantry is currently displaying, presumably for the purpose of anyone disputing it?

Edit: https://www.whatdotheyknow.com/request/with_variable_speed_cameras_are

That's not where I've read it before but it backs up my original thoughts.

robj20 · 12 Mar 2019 at 12:50

Am i right in thinking these sort of cameras and smart motorways aren't average speed cameras.

ci_newman · 12 Mar 2019 at 13:13

Hyburnate said:
In that case, I think we can safely disregard anything that website has to offer

e; website that seems to state the camera that is in use on the M25

https://www.speedcamerasuk.com/hadecs-3.htm

Yes, the M25 uses HADECS3 cameras. That website is still wrong anyway, it says they are "stealth" cameras because they are painted grey, but that was only the trial cameras. All cameras capable of taking tickets are yellow. We've had them on the M3 for over a year and that website says they will be installed "soon".

(source: my wife was one of the Engineers that worked on the designs of the cameras - thankfully she has since left that job though

)

Meaker · 12 Mar 2019 at 13:52

Depends on the road, i'd assume 8-10 seconds to be on the safe side so if you are literally passing under as it changes then that's fine.

wolfie138 · 12 Mar 2019 at 14:23

surely they'd be able to tell from your speed etc that you would have been under the gantry at the time and not had time to slow w/out doing unsafe braking?

IAmATeaf · 12 Mar 2019 at 15:57

wolfie138 said:
surely they'd be able to tell from your speed etc that you would have been under the gantry at the time and not had time to slow w/out doing unsafe braking?

So you think that every ticket is reviewed by a human?

wolfie138 · 13 Mar 2019 at 08:42

IAmATeaf said:
So you think that every ticket is reviewed by a human?

do you not understand programming the issue system to look for certain events?

ezekial · 13 Mar 2019 at 09:09

I really wouldn't worry about it. I believe the grace period is 1 minute. I personally have been flashed about 4 or 5 times on the M25, sometimes with the speed limits in place, sometimes without. In fact I believe one of those was coming back from Gatwick at about 11pm and I got flashed near the Cobham services, no other cars around so I know it was me who triggered it. Still no fine. I think these cameras malfunction quite often.

IAmATeaf · 13 Mar 2019 at 09:44

wolfie138 said:
do you not understand programming the issue system to look for certain events?

Hmm not too sure, it all depends what actually get recorded. If all the system knows is when and what speed you passed the last gantry and then this gantry, that's assuming that it does this it has no idea what speed you were doing as you approached. As it's variable I've seem people floor it between gantries and then slam on their brakes. If each gantry is independent then all it has is the cut in/off time when the speed goes up/down.

Meaker · 13 Mar 2019 at 09:49

ezekial said:
I really wouldn't worry about it. I believe the grace period is 1 minute. I personally have been flashed about 4 or 5 times on the M25, sometimes with the speed limits in place, sometimes without. In fact I believe one of those was coming back from Gatwick at about 11pm and I got flashed near the Cobham services, no other cars around so I know it was me who triggered it. Still no fine. I think these cameras malfunction quite often.

They do take test firings to calibrate themselves too.

CaptainRAVE · 13 Mar 2019 at 10:40

These cameras must be making a fortune. I don't get why people don't slow down for them. I see so many flashes and I don't even drive on there much. You literally just need to slow down for the lines for the gantry cameras.