m25 gantry cameras

[Batfink]

I was driving along the motorway yesterday and after a long day I was just matching the front car for speed. I went through a variable gantry camera at just over 50mph when it flashed 40mph so the camera actually worked.

Opps! I admit i wasent really paying attention to my speed so i wont cry if a notice comes through the door, but I was wondering if they actually work.

Guess I find out in 14 days anyway :P

[andy_quantum]

I think there's a delay of about 10 seconds for the lower limit enforcement if there is a camera on that particular bridge

Ah, I re-read your post. I thought you meant the limit changed from 50 to 40, but what you mean is you went through a 40 at 50. AFAIK the ones that flash do work

Edited by andy_quantum on Thursday 8th November 10:54

[Triple7]

I'd say, more likely not to get a ticket, but don't hold me to it.

G

[SplatSpeed]

one flash usually empty

two = done

[Towie]

SplatSpeed said:

one flash usually empty

two = done

Where on earth did you find that little gem??

[jwo]

Has anyone ever been caught by an m25 gantry camera? I know of no one that has!

[SimonMaidenhead]

My ex got done at 56 when it was flashing 50. I went through one nearly 3 weeks ago when it was flashing 60 and was doing considerably more than this........nothing yet.
How long do they take to come through?

[mph999]

andy_quantum said:

I think there's a delay of about 10 seconds for the lower limit enforcement if there is a camera on that particular bridge

Ah, I re-read your post. I thought you meant the limit changed from 50 to 40, but what you mean is you went through a 40 at 50. AFAIK the ones that flash do work

Edited by andy_quantum on Thursday 8th November 10:54

I believe the delay is longer, was told 2 mins by a Surrey traffic plod, but this seems a little generous.

Martin

[Mattt]

I've known plenty of people flashed, none have got tickets - although I hear that the more southernly ones are more likely to have film, true or not, I don't know.

[Scraggles]

since the cameras are digital and not use film, suspect anyone who speeds thru them might have hassles, considering there is a very, very high chance of being a jam the other side, see no point in speeding just to get to the jam 1-2 mins early

[futie]

SimonMaidenhead said:

My ex got done at 56 when it was flashing 50.

That's odd - i'm regularly 10 mph over the posted limit and have never been flashed, let alone NIP'd. Speedo seems to be pretty accurate compared with GPS too.

[Dunk76]

They seem to vary with regards trigger point - the two C/W running up to J13 (M3) seemingly the keenest.

I've sat in traffic A/C and watched people thump through them only marginally faster than the other traffic and get flashed.

Years ago, when I had a foreign registered car, I did some experimentation - although there were far more cameras at the time - the trigger point seemed to be >9mph over the posted variable limit, and >22mph when no variable in place.

[Blue160]

I drive round that section of the M25 every day

I've never paid any attention to the cameras, and have never had a ticket.

Might slow down a bit after reading some of these posts though!

[Vesuvius 996]

My Road Angel certainly says they work!!

[JonRB]

SplatSpeed said:

one flash usually empty

two = done

Sorry, but total boocks. It always flashes twice whether full or empty. The latter is called "dummy mode".

mph999 said:

I believe the delay is longer, was told 2 mins by a Surrey traffic plod, but this seems a little generous.

It's anything from 0-99 mins from memory, so 2 mins is quite feasible.

Scraggles said:

since the cameras are digital and not use film

The M25 gantry cameras are film-based modified GATSO cameras. Well, the CMIIS that's been there for the past 10 years is. I don't think they've been replaced by a newer digital system.

Dunk76 said:

Years ago, when I had a foreign registered car, I did some experimentation - although there were far more cameras at the time - the trigger point seemed to be >9mph over the posted variable limit, and >22mph when no variable in place.

The trigger point is operator-defined for each speed limit (Red X, 20, 30, 40, 50, 60 and NSL) and is 0-99mph for each (ie. a threshold of 19 mph on the 50 mph limit means a trigger speed of 69 mph). And since this is stored in a data file on a flash card physically inserted into the camera, it is a per-camera setting and could change each time the film is changed since the a log file records all enforcements etc. on it in additional to the photographs, so I would imagine the card gets changed the same time as the film. However I doubt that the thresholds are changed all that often in practice.

Edited by JonRB on Friday 9th November 16:48