Are the overhead cameras on the M25 always live?

[derekmuesli]

Does anyone know if any of those overhead GATSOs on the M25 between the A3 and the M4 are live ? Has anyone been caught by them recently ? My other half seems happy that unless a variable speed limit is displayed, they are not active and she persists in flying under them - so far with apparent impunity - touch wood ;-) (She''s been doing it for a long time..) I remember reading something a year or two back about a speeding case being thrown out because those boxes were not designed to work in such close proximity to one another as their radars could interfere with each other.

[apguy]

Word from a genuine motorcycle traffic officer is that: a) The cameras are live under normal, non-variable limits. b) The trigger speed is deliberately set high. The confirmed trigger speed under normal, non-variable limits is 90mph. Normal caveats apply. Also the cameras have the usual numbers of dummy units, out of film or just not switched on.

[JonRB]

I think I can answer that one because............ ...........I was a member of the team that designed and built them in 1994, and I wrote the software for it. Before the abuse starts, I'd like to point out that the system was designed to prevent gridlock by slowing down traffic coming into a traffic jam to below the speed of the traffic coming out of the jam, so the jam unblocks itself. Unfortunately the technology to do this also allows the police to use it as a speed trap, which was not the intention of the team, some of whom (myself included) are real car enthusiasts. Anyway, in answer to your question, the default behaviour of the system is not to enforce (ie. take pictures of you) when the matrix boards are not displaying a speed. However, the operator can override this and the system is quite capable of enforcing when "NS" (National Speed Limit) is in effect. So your information is probably correct - at the moment they have it set not to enforce at NS. Doesn't mean this will always be the case though, as they can simply turn it on when funds get too low (allegedly). Oh, and before anybody asks, the system does not recognise numberplates, so, no, there is no backdoor that lets me off if I drive under one. Regards Jon

[mel]

Judus. Hang him

[PetrolTed]

I've been flashed when the normal limit is in force. I was doing over 90mph and thought they may not work. They do. I didn't get a ticket though.

[JonRB]

Aww, let me off! It was 7 years ago and I was young and impressionable and believed the hype that we were building something that would benefit motorists rather than penalise them. How was I to know the country would go GATSo crazy? Edited by JonRB on Wednesday 26th September 11:00

[smeagol]

I forgive you John. I used to know a chap that developed the measuring of skid marks to determine speed. He got caught using his own system

[salty]

Hmmm, interestingly (or not) enough. During last years Euro 2000 semi-final (think it was), I was unfortunately down in Camberley. I managed to see the 1st 10 mins, then decided to head off back to London. Absolutely superb drive. Hardly any cars on the M3 (150+ woo hoo!), hit the M25, and was suprised to see 40 Mph signs on the supposed "jam avoiding" variable speed limits. Strangely enough it would have been normal "rush hour" trafic, except that everyone was at home watching the game. I'd be interested to know whether they ARE really variable cameras, or pre-programmed to drop the speed on those stretches of road. Anyone know?

[smeagol]

I bet the people who are supposed to vary the cameras were also watching the game!

[JonRB]

Its a popular misconception that the system sets its own speeds. It doesn't. It is a Variable Speed Enforcement System because it is able to enforce at variable speeds (duh) which other cameras can't. It is the operators who set the speed - the cameras are not autonomous. So if it is displaying an inappropriately low speed its because some bozos in a control centre somewhere have set the speed, not the cameras. There was an add-on system called MIDAS that was being developed at the same time that was going to use inductance loops to measure traffic flow and then automatically set the speed for variable enforcement. I beleive it went way over time and budget and I've not heard much about it since. But it was a completely separate system being developed by a completely separate part of the company and I only every heard it mentioned in passing a couple of times. Definitely not a proper parallel development or collaborative thing. I don't think it was ever finished. So as far as I am aware, the cameras still do not set their own speeds. Edited by JonRB on Wednesday 26th September 11:57

[adrianr]

quote:It is the operators who set the speed - the cameras are not autonomous. So if it is displaying an inappropriately low speed its because some bozos in a control centre somewhere have set the speed, not the cameras.

That figures. My unscientific observations conclude that these things generate jams... they may possibly reduce the number or severity of accidents but speed up the traffic flow, nope. AdrianR

[JonRB]

Well, that's the point of a Pilot Scheme, isn't it? Hopefully the "Powers That Be" will come to the same conclusion and conclude that the system hasn't fulfilled its goals and learn appropriate lessons. (As if) Edited by JonRB on Wednesday 26th September 12:26

[adrianr]

How about a much simpler suggestion - just have a single "congestion" warning, which means max 55mph, stay in lane, pass either side. This would remove one of the most annoying features of the current system which is the fluctuating limit; if people slow down too early in anticipation or suddenly at the sign in the hope that it'll change before you get there then you create more problems than you solve. The hope is that (i) traffic gets distributed across all lanes and (ii) People who are used to driving at 70 can do merges and lane changes at 55 in heavy traffic without the sudden braking which causes compression jams. AdrianR

[RichB]

quote:So if it is displaying an inappropriately low speed its because some bozos in a control centre somewhere have set the speed, not the cameras.

Like the other morning when I was on my to catch an early flight from Gatwick. Went along the M25 at about 5:30 am first few gantrys nothing, then a 60, then a 40 then another 60 then nothing. You guessed it the road was absolutly clear. If there had been an earlier accident why can't they switch the bloody things off? No wonder motorists have such little respct for the plod. Obviously just out to get a few extra quid in stealth tax that morning by leaving them on for a few houyrs afyter the event I reckon

[mel]

Even easier answer would have been to put an extra couple of lanes in ! Bugger the tree huggers

[derekmuesli]

Cheers for the info... hopefully I can at least talk the missus into staying under 90.. ;-) For what it's worth, when it's working properly, the VSL seems a reasonably successful way of regulating traffic flow - of course there's nothing it can do to compensate for a complete block - by an accident or such like - but it does help prevent the waves of sudden braking and bunching up you get on the M6. I'll get me coat...

[smeagol]

One of the biggest causes of waves are lorries overtaking each other with a speed difference of 2mph. It effectivly makes a motorway into a single lane. Mels absolutly right more lanes would stop the problem of congestion. Another method is to put the freight onto trains. I believe France has trains that lorry drivers drive onto (like the channel tunnel idea) and drive off at the most appropiate station. Makes good sense to me AND solves a lot of problesm we have with congestion and road surfaces.

[derekmuesli]

This is the first I've heard of putting the lorries onto trains - dunno why I didn't discover it earlier. Still, I think we'll all agree that the rail infrastructure is creaking at the seams as it is. So I'm not sure we'll ever see anything like that here.. :-( Do you think the 56mph limiters help or exacerbate this phenomenon of overtaking at microscopically different speeds ? When the lorrys had no limiters and could all do 60mph you'd get them creeping up to 62-65mph which is bad (me speeding good.. 38t lorry speeding bad ). Is anyone here optimistic enough to seriously believe we'll ever get additional lanes whilst the tree-huggers are busy shoving twigs up the politicians noses ? Edited by derekmuesli on Wednesday 26th September 19:51

[big rumbly]

In France they adopt the practice of not letting lorries overtake on uphill stretches of two lane carriageways, blindingly simple, why not here?

[derekmuesli]

Indeed - same in Germany and Belgium (Probably NL too).. But then they also have zipmerging as a recommended practice and TV ads to that effect.. in this country the powers that be frown upon zipmerging.. clearly they prefer waves of emergency braking and muppets who won't let you in because you're 'cutting in' the queue. There's are a lot that could be learned by a good look at how they deal with some of these things in northern Europe. (Well, what would be the point of looking at Greece?) Edited by derekmuesli on Thursday 27th September 16:53