Variable Speed Gantry Cameras - some info

[developer]

I was at Autosport International last weekend, chatting to a couple of West Midlands police officers on their stand.

I asked about the functionality of said cameras when the gantry speed limit signs appeared to be switched off, i.e, without a nominated maximum speed showing.

They explained that if you were to exceed 70mph "by some margin" then the gantry camera would activate.

They wouldn't be drawn on an exact figure, but the point is that the cameras are on even when the signs are off (if you choose to believe them of course).

Just sharing it really.

Because this is a forum I should clarify that they were West Midlands police, speaking about the variable speed sign/camera sections of the M42 and M6 in their region.

 

[boxbrownie]

On the Essex stretch of the M25 couple of weeks ago both direction were NSL under the gantries and several times I saw flashes on the opposite carriageway, so yes it appears that would be correct, and a few motorists will be getting a surprise soon!

 

[Wheelsnuts]

Yes, seen the same on the M1 near Nottingham.

 

[Bobby Dazzler]

There was something in the press (Birmingham Post maybe?) about the gantry cameras being activated at 70mph sharp even when the variable speed limit is not place - currently the cameras being only active when the variable limit is active.

There was also a reference to additional cameras without signage. Might be worth a Google, as I only half read it.

 

[regbuser]

by observation during frequent journeys up and down the 4 lane section of the M1, I think the gantry cameras snap above 99mph, i.e at 100.

 

[developer]

There was something in the press (Birmingham Post maybe?) about the gantry cameras being activated at 70mph sharp even when the variable speed limit is not place - currently the cameras being only active when the variable limit is active.

There was also a reference to additional cameras without signage. Might be worth a Google, as I only half read it.

It was that article (today) that reminded me of my conversation .

 

[Peter T]

Stealth cameras on M25 in Kent have caught 700 drivers in two months | Daily Mail Online

 

[E280wilson]

Big article in the Sun today about this on the M25 in Kent. 1500 drivers in 10 weeks. 780 doing over 70. Camera is working all the time.

 

[Blowpipe]

By way of contrast, what a great idea..

Swedish Speed-Camera Pays Drivers to Slow Down | WIRED

 

[modelman093]

Article in the Sunday Times suggesting that the gantry cameras are now active even when not showing reduced limits and also about the new Hadecs cameras, small and grey on a grey pole, no white markings on road and covering all lanes and the hard shoulder on "smart motorways".
The implication was that the Hadecs do not allow much margin over 70 or whatever limit is shown on the gantry.
Be careful out there!

 

[carat 3.6]

Between the m4 and m40 junctions of the m25 there is an unofficial speed limit of 100mph, never seen or heard of anyone getting caught by a camera there.

 

[dozypillock]

Between the m4 and m40 junctions of the m25 there is an unofficial speed limit of 100mph, never seen or heard of anyone getting caught by a camera there.

Been through there many many times over the years. Always stick to around 90, and never been ticketed.
I must admit, as I have got older, I am more wary when the 60, 50, 40 limits show, but still see others carry on as normal.
What annoys me is when they say accident, 40 etc, and you go for a couple more miles, then unlimited again, and nothing was seen?
Were they just having a laugh? or did some lazy twonk forget to turn it off after the accident was cleared 3 hours ago?

Neil

 

[markjay]

A few unrelated comments (in no particular order):

A. It is possible that the cameras flash at 70 but the police do not actually follow up each photo with prosecution - so the cameras flashing and the speeding guideline could still be reconciled, in theory at least (no idea - just raising the possibility).

B. In the olden days they used to say that only 25% of speed cameras actually have film in them - the rest are just flashing as a deterent. Film is obviously no longer an issue as the cameras are all digital now, but I wonder if even in the digital camera age some are set to 'deter' only?

C. Having driven at speed, flashed, and not received a letter in the post is not proof that the cameras don't work... there could be several technical reasons while prosecution did not follow, e.g. equipment malfunction, image not clear enough, another car in the frame, or whatever it is that might not meet the criteria for successful prosecuting etc - a one off experience is not the same as statistical evidence.....

 

[carat 3.6]

What annoys me is when they say accident, 40 etc, and you go for a couple more miles, then unlimited again, and nothing was seen?
Were they just having a laugh? or did some lazy twonk forget to turn it off after the accident was cleared 3 hours ago?

Neil

I've had that a few times recently. First you get a sea of brake lights, then all 3 lanes come to a standstill for a few seconds, then you are on your way again. All because one gantry has a 40mph sign lit up, but then nothing on the next one.

Seen a few accidents caused by that. :fail

 

[John Jones Jr]

Between the m4 and m40 junctions of the m25 there is an unofficial speed limit of 100mph, never seen or heard of anyone getting caught by a camera there.

At one time it was flat out all the way uphill to the M1 junction and pull whatever speed your car could handle comfortably while joining the M1 and then blast all the way up to junction 15 & 15a before meeting a camera. Manchester or Holyhead never seemed that far away! Really didn't know how lucky I was back then.

 

[carat 3.6]

The m40 from junction 8 northwards has become a bit of testing ground lately, there's some serious metal using that road!

 

[st13phil]

The m40 from junction 8 northwards has become a bit of testing ground lately, there's some serious metal using that road!

There's a favourite spot for TVP patrols between J8 & J9, where they "hide" in the dip around the Boarstall Wood / Oakley Wood area and ping the unwary as they come into view.

 

[guydewdney]

Between the m4 and m40 junctions of the m25 there is an unofficial speed minimum of 100mph, never seen or heard of anyone getting caught by a camera there.

Fixed that for you.:bannana:

 

[meeeb]

I've had that a few times recently. First you get a sea of brake lights, then all 3 lanes come to a standstill for a few seconds, then you are on your way again. All because one gantry has a 40mph sign lit up, but then nothing on the next one.

Seen a few accidents caused by that. :fail

You may have got that wrong. The 40 is probably on because of the congestion, not vice versa.

If traffic is heavy and there's an incident which causes congestion and causes vehicles to slow down at that point, an identical situation can continue long after the incident has been cleared so it looks as though the speed restriction is causing the problem.

This can also occur simultaneously on the opposite carriageway when that perennial pestilence rubberneckers slow down for a gawp, and cause the same phenomenon.

I remember reading many years ago an article in a French magazine reporting that scientists were trying to explain this bizarre vehicular behaviour.

 

[stevehg]

The new haldecs cameras are video only, there will be no flash. They are also able to calculate average over any of the sets along the system they are deployed in and can cope with lane changing.

In these new average speed areas its at local discretion on the trigger level, unfortunately no national guidelines, so it's anyone's guess at what percentage over the limit they will trigger. I would suspect you'd be easily safe at 75mph in a 70 as they have to allow for speedo accuracy and the fact that you get ~2% difference between brand new and worn tyres. So I can't see even the aggressive authorities like Kent etc. Going below this, however, I think the old philosophy of 10% +2mph won't be safe in some areas.