The M25 "Queue Ahead" game
Discussion
Today I had the treat of travelling the M25 from J8 heading clockwise (Reigate to Leatherhead). For a change "google maps" reported all clear - not a trace of red - but after a couple of miles the overhead gantry sign said "queue ahead" with a 40mph speed restriction. Traffic was fairly sparse and travelling reasonably quickly but at the next gantry the brake lights went on (because of the speed camera) and everything got bunched up. The following gantry the "derestricted" (circle with oblique line through it) is illuminated. I have seen this happen before on this stretch. I do not know what muppetry goes on in the control room - perhaps they were trying to pay for the Queen's birthday present? Does anyone know whether these restrictions are activated by people or just follow some computer algorithm? Perhaps this is just an "obedience" test?
I've seen this a few times, although usually for an "incident" which has been as little as a single car on the shoulder. To be fair, there are usually plenty of queues ahead on the M25, surely these are mostly set automatically based on data from car counters? If so, it's the data model that's a mess, rather than day-in day-out human error... I'd be interested to know how it's done!
Beggarall said:
Today I had the treat of travelling the M25 from J8 heading clockwise (Reigate to Leatherhead). For a change "google maps" reported all clear - not a trace of red - but after a couple of miles the overhead gantry sign said "queue ahead" with a 40mph speed restriction. Traffic was fairly sparse and travelling reasonably quickly but at the next gantry the brake lights went on (because of the speed camera) and everything got bunched up. The following gantry the "derestricted" (circle with oblique line through it) is illuminated. I have seen this happen before on this stretch. I do not know what muppetry goes on in the control room - perhaps they were trying to pay for the Queen's birthday present? Does anyone know whether these restrictions are activated by people or just follow some computer algorithm? Perhaps this is just an "obedience" test?
I'm not convinced by it, but they will claim the managed speed restrictions have kept the traffic flowing.Beggarall said:
Today I had the treat of travelling the M25 from J8 heading clockwise (Reigate to Leatherhead). For a change "google maps" reported all clear - not a trace of red - but after a couple of miles the overhead gantry sign said "queue ahead" with a 40mph speed restriction. Traffic was fairly sparse and travelling reasonably quickly but at the next gantry the brake lights went on (because of the speed camera) and everything got bunched up. The following gantry the "derestricted" (circle with oblique line through it) is illuminated. I have seen this happen before on this stretch. I do not know what muppetry goes on in the control room - perhaps they were trying to pay for the Queen's birthday present? Does anyone know whether these restrictions are activated by people or just follow some computer algorithm? Perhaps this is just an "obedience" test?
I believe, although stand to be corrected, that it's the sensors in the road. It detects slower moving traffic and changes the speed limit and puts up the gantry signs. It sometimes clears quickly, but the signs stay up for a little while, until it resetBeggarall said:
Today I had the treat of travelling the M25 from J8 heading clockwise (Reigate to Leatherhead). For a change "google maps" reported all clear - not a trace of red - but after a couple of miles the overhead gantry sign said "queue ahead" with a 40mph speed restriction. Traffic was fairly sparse and travelling reasonably quickly but at the next gantry the brake lights went on (because of the speed camera) and everything got bunched up. The following gantry the "derestricted" (circle with oblique line through it) is illuminated.
OK : So M25 I've not done it but I know it's the London ring-road but it sounds like they put up the 'Que Ahead' request then eveyrone did it then it was over and eveyrone went back up to normal speed?If the system works as it should then you'll experience the queue warning, the speed restriction, and by the time you get there it will have gone (because you were slowed on the approach).
There are videos available on You Tube that explain how this works, not that I think they're necessary as it's reasonably obvious when you think about it.
There are videos available on You Tube that explain how this works, not that I think they're necessary as it's reasonably obvious when you think about it.
The signs are operated by humans from the control room. Often if they spot a high volume of traffic miles in the distance, they will slow traffic down miles behind to keep the M25 flowing (in an ideal world ), so on a lot of these occasions when a reduced limit is enforced, there is no immediate queue, it just staggers the flow of traffic to keep everything (hopefully) moving along.
krisdelta said:
I've seen this a few times, although usually for an "incident" which has been as little as a single car on the shoulder.
Unless you are mystic Meg how do you know that vehicle wasn't stranded live lane prior to your arrival ? Or the owner hasn't just been wandering in the carriageway to collect an errant bike/suitcase/inserterrantitem here.Speed Badger said:
The signs are operated by humans from the control room.
Anyway this subject has been done to death before I'm out as is one of the best most knowledgeable RCC operators in the land as Gafferjim completes his last shift and retires today, I'm pretty sure he's taken a bunch of PH's around one of the RCC's.
speedyguy said:
krisdelta said:
I've seen this a few times, although usually for an "incident" which has been as little as a single car on the shoulder.
Unless you are mystic Meg how do you know that vehicle wasn't stranded live lane prior to your arrival ? Or the owner hasn't just been wandering in the carriageway to collect an errant bike/suitcase/inserterrantitem here.Speed Badger said:
The signs are operated by humans from the control room.
Anyway this subject has been done to death before I'm out as is one of the best most knowledgeable RCC operators in the land as Gafferjim completes his last shift and retires today, I'm pretty sure he's taken a bunch of PH's around one of the RCC's.
I understand the theory of what is trying to be achieved. What I don't get is the different limits at different gantries. You can go from nsl to 60, then to 50, then 40, back up to 60, down to 40 again all in a short section of road.
Once that starts happening people start ignoring the signs
Once that starts happening people start ignoring the signs
pmanson said:
I understand the theory of what is trying to be achieved. What I don't get is the different limits at different gantries. You can go from nsl to 60, then to 50, then 40, back up to 60, down to 40 again all in a short section of road.
Once that starts happening people start ignoring the signs
That's usually because of the bell-ends who speed up between cameras. It causes increase flow in areas the system is trying to slow down, so introduces more draconian measures. Quite simple really. The fix would be more cameras and enforced averages, but tests expensive to implement. Ideally if people could just chill out a bit and realise that by adding 15-30 mins to a journey massive 3-5 hour traffic jams are being avoided.Once that starts happening people start ignoring the signs
M25, 3am, off to the Eurotunnel on the way to France. All of a sudden, the 40 signs are lit.
I was the only car on my side of the motorway. Needless to say, I cheated a bit between the signs, easy in an XJR.
Eventually I caught up with the problem. It was a low loader transporting a diesel locomotive, a type 47 for any train spotters out there! Crawling along in the nearside lane.
The irony was that I had just finished work at Reading where I was a train driver.
In my opinion, that's a pretty poor reason for having those 40 signs lit.
I was the only car on my side of the motorway. Needless to say, I cheated a bit between the signs, easy in an XJR.
Eventually I caught up with the problem. It was a low loader transporting a diesel locomotive, a type 47 for any train spotters out there! Crawling along in the nearside lane.
The irony was that I had just finished work at Reading where I was a train driver.
In my opinion, that's a pretty poor reason for having those 40 signs lit.
Poshbury said:
M25, 3am, off to the Eurotunnel on the way to France. All of a sudden, the 40 signs are lit.
I was the only car on my side of the motorway. Needless to say, I cheated a bit between the signs, easy in an XJR.
Eventually I caught up with the problem. It was a low loader transporting a diesel locomotive, a type 47 for any train spotters out there! Crawling along in the nearside lane.
The irony was that I had jed work at Reading where I was a train driver.
In my opinion, that's a pretty poor reason for having those 40 signs litust finish.
And had you stuck to the 40mph limit you would probably never have caught up with the low-loader! That seems to be a ridiculous reason to limit the motorway for miles, especially at night. This might even be a situation where it would be helpful to put a notice on the illuminated gantry boards - just as a warning/advice. Also it seems easy to turn the limits on so presumably just as easy to turn them off so that you don't have miles of "Workforce on the road" restrictions for a short section of activity a long way ahead. The problem is that on these occasions the extent of the restrictions seems excessive and thus limits the credibility of the signage. I was the only car on my side of the motorway. Needless to say, I cheated a bit between the signs, easy in an XJR.
Eventually I caught up with the problem. It was a low loader transporting a diesel locomotive, a type 47 for any train spotters out there! Crawling along in the nearside lane.
The irony was that I had jed work at Reading where I was a train driver.
In my opinion, that's a pretty poor reason for having those 40 signs litust finish.
The infamous "queue on sliproad" coupled with 60, 50, 40 restrictions on the M25 clockwise to A10 junction.
The "queue" can be anything from a couple of cars waiting at the roundabout to a line taking up lane one for a mile
How is this helping? People see the signs and panic, swerve into L1 to join the non-existent queue which has a knock-on effect in the other lanes.
The "queue" can be anything from a couple of cars waiting at the roundabout to a line taking up lane one for a mile
How is this helping? People see the signs and panic, swerve into L1 to join the non-existent queue which has a knock-on effect in the other lanes.
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