Reply to: M4 average speed cameras trap 6,500 in south Wales

[doodab]

I said

My journey was m40 - No holdups, M42 holdups caused by the variable speed thing, M6.

meaning I travelled up the M40 with no holdups. I travelled up the M42 at the speed reduced because of the variable speed thing and then onto the M6 where I again got no holdps. The M42 itself was empty, because, leaving London at 6 I would hit it at some point past 7pm, usually around 7:30. The rush hour ended long ago and that could be seen by there being no traffic on the M40 or on the M42 itself or later on the M6.

My point about seeing the speed limits ahead was to show how stupidly short the restrictions were applied to. 2 of the overhead things were showing reduced speeds and the third was showing that the restriction had been lifted. The 3rd could easily be seen before you went under the second. You tell me how reducing the speed for such a tiny distance and for the tiny number of vechicles on the motorway can effect the state of a motorway further up. Also, tell me why this is the case every single Thursday night!




I'm saying, at that time of night unless an accident had occurred, it was allways free flowing. I'm fully aware of the congesstion in that area at peak times as I have done this journey hundreds of times over the years. I did this journey every thursday night from 2001 to 2004, when the scheme was not in place and never had holdups on that bit of road at that time of night. Yes there were significant holdups when they were putting it in place, but the M42 was fine back then, as was the M6, because at 8pm (the time I usually got to the M6) it was quiet also. That is why I used to travel on a Thursday night, because there were no holdups.

In terms of your links, I have no issue with the traffic management on the M42 during peak times - only when it is left on at times when there is obviously no traffic on the road.

Then write to them and complain using the link above. It's no good telling me cos I can't do anything about it.

[BoredBloke]

I am very impressed that you can see the entire motorway network from your drivers seat, although slightly surprised that using google is beyond you.

I said

My journey was m40 - No holdups, M42 holdups caused by the variable speed thing, M6.

meaning I travelled up the M40 with no holdups. I travelled up the M42 at the speed reduced because of the variable speed thing and then onto the M6 where I again got no holdps. The M42 itself was empty, because, leaving London at 6 I would hit it at some point past 7pm, usually around 7:30. The rush hour ended long ago and that could be seen by there being no traffic on the M40 or on the M42 itself or later on the M6.

My point about seeing the speed limits ahead was to show how stupidly short the restrictions were applied to. 2 of the overhead things were showing reduced speeds and the third was showing that the restriction had been lifted. The 3rd could easily be seen before you went under the second. You tell me how reducing the speed for such a tiny distance and for the tiny number of vechicles on the motorway can effect the state of a motorway further up. Also, tell me why this is the case every single Thursday night!

I think the problem with your understanding is that you assume that the M42 would be free flowing if there were no variable speed limits. As someone who used to drive down it regularly before this scheme was launched I can assure you this wasn't the case, and I would happily bet that although there is still some congestion that the average journey time is reduced despite an increased volume of traffic. In fact here are some numbers:

Highways Agency - Active Traffic Management

You can tell them how wrong they are here:

Highways Agency - Contact us form

I'm saying, at that time of night unless an accident had occurred, it was allways free flowing. I'm fully aware of the congesstion in that area at peak times as I have done this journey hundreds of times over the years. I did this journey every thursday night from 2001 to 2004, when the scheme was not in place and never had holdups on that bit of road at that time of night. Yes there were significant holdups when they were putting it in place, but the M42 was fine back then, as was the M6, because at 8pm (the time I usually got to the M6) it was quiet also. That is why I used to travel on a Thursday night, because there were no holdups.

In terms of your links, I have no issue with the traffic management on the M42 during peak times - only when it is left on at times when there is obviously no traffic on the road.

[doodab]

Well explain how this happens every Thursday night when the motorways are quiet. If it was once in a while then yes I could agree that this was to reduce the supply of traffic to a problem further up the road. This isn't what happens. My journey was m40 - No holdups, M42 holdups caused by the variable speed thing, M6. Because the traffic was that light I never used to toll road yet the traffic on the m42 had the speed restrictions on all the time.

I am very impressed that you can see the entire motorway network from your drivers seat, although slightly surprised that using google is beyond you.

I think the problem with your understanding is that you assume that the M42 would be free flowing if there were no variable speed limits. As someone who used to drive down it regularly before this scheme was launched I can assure you this wasn't the case, and I would happily bet that although there is still some congestion that the average journey time is reduced despite an increased volume of traffic. In fact here are some numbers:

Highways Agency - Active Traffic Management

You can tell them how wrong they are here:

Highways Agency - Contact us form

[BoredBloke]

Perhaps you should think to yourself "hey I drove home and didn't see any congestion, aren't these traffic monkey's clever" rather than second guessing them?

Well explain how this happens every Thursday night when the motorways are quiet. If it was once in a while then yes I could agree that this was to reduce the supply of traffic to a problem further up the road. This isn't what happens. My journey was m40 - No holdups, M42 holdups caused by the variable speed thing, M6. Because the traffic was that light I never used to toll road yet the traffic on the m42 had the speed restrictions on all the time.

Last week I went up and there was one sign slowing things to 60 followed by another to 50 and further up you could see the one lifting the restriction. You could also see that the traffic was light, the 3rd lane was actually totally empty and there was nothing in the road or on the hard shoulder. The restrictions were on for about a mile - how can slowing hardly any traffic for such a short distance onto a motorway with no traffic have any beneficial effect?

[doodab]

Perhaps you should think to yourself "hey I drove home and didn't see any congestion, aren't these traffic monkey's clever" rather than second guessing them?

[BoredBloke]

Traffic jams & congestion propagate similarly to sound waves. They often aren't caused by an accident or similar but are more akin to a "sonic boom". By slowing you down to 40 a few miles away from where the "compression wave" is they are eliminating or reducing the probability that you run into the back of it and have to slow right down or stop.

I'm fully aware of that - I'm also aware that at 7/8pm each thursday night when I used to drive from london to the North West, there was never any traffic jam anywhere on the route I used, yet these variable speed limits were still in place. This isn't some kind of high tech mechanism to keep the small amount of traffic flowing freely, it's because nobody thought to switch them off after the rush hour finished long ago.

Last week they had them on 2 signs up, one slowing to 60 and the next to 50 and then one lifting the restictions. As you approached the 50 one you could see the one in the further along lifting the speed restriction.

As I said, often they would have the speed set to 60 or 50 and there would be sod all in the outside lane due to the lack of cars on the motorway at that time.

[Clippy]

I know, I didn't see the tests where it failed until after I'd driven one!

Merc's just as crap too.

[DaveB]

Good job you didn't.

I know, I didn't see the tests where it failed until after I'd driven one!

[Clippy]

Volvo have it as an option on most of their cars now as well. Test drove an SC60 with it a while back and your right, it is very weird. Especially when it speeds up without you telling it to when he car in front gets out of the way!

I didn't have the balls to test the collision prevention

Good job you didn't.

[DaveB]

Traffic jams & congestion propagate similarly to sound waves. They often aren't caused by an accident or similar but are more akin to a "sonic boom". By slowing you down to 40 a few miles away from where the "compression wave" is they are eliminating or reducing the probability that you run into the back of it and have to slow right down or stop.

WHS. This is why it takes so long for jams to clear even though the cause has long since gone.

When the obstruction has cleared the whole queue doesn't start moving simultaneously, each vehicle has to wait for the one in front to start moving. In a long queue, with traffic still arriving at the back of it and and stopping as it does, it can take a long time for the moving 'front' to reach the back.

By slowing everyone down behind the queue before the arrive at the back you stop it growing faster than it can disperse and everyone moves faster than they would have done otherwise.

[doodab]

The variable ones do my fruit in! Last week on the M42 at 9pm they had 2 signs on slowing the traffic to 50 and then 40. There was nothing there - no accident, nothing!! All they did was slow an empty motorway down.

Quite often when I used to drive back on a Thursday night the variable speed thing would be set to 60 when the outside lane was empty due to the motorway being quiet. Are they on a timer?

Traffic jams & congestion propagate similarly to sound waves. They often aren't caused by an accident or similar but are more akin to a "sonic boom". By slowing you down to 40 a few miles away from where the "compression wave" is they are eliminating or reducing the probability that you run into the back of it and have to slow right down or stop.

[d000hg]

My Range Rovers had adaptive cruise control. Spooky stuff but it worked once you learned to trust it.

That's nothing: BBC News - Google tests cars that drive themselves

[Peoplesoft bloke]

Regardless of the merits of speeding cameras and fines, surely getting caught speeding in an average speed zone deserves a permanent ban for stupidity? It's not as if there's a lack of signs saying "Average Speed Camera Zone" or similar and the big yellow overhanging cameras aren't exactly hidden behind bushes like the old pre-yellow GATSOs.

I don't mind putting my foot down occasionally and if I get caught then I accept my fate with a sigh and call to the insurance company (9 points over the last 15 years) but to get caught in one of these new average speed zones is surely just daft and throwing money and points away.

Totally agree - you must be a special kind of moron to get done for speeding in a camera average zone

Don't you feel pressurised to conform to other motorists speeds and general motorway madness? Well, you must do if you are encroaching a car in front, but even in the slow lane there's a great deal of pressure to close gaps and to increase speed if a juggernaut starts tailgating. I'd feel uncomfortable using cruise control.

No - if they want a speeding fine that's their lookout. I usually ignore tailgaters but particularly bad cases usually result in me slowing down quite a lot.

Lorries won't tailgate if you do the speed your sat-nav shows rather than your under-reading car speedo

Bollocks. There is a significant proportion of lorry drivers, who like BMW and Audi prats, will taligate anyone under any circumstances at any time. It's just they way they drive.

I generally use my adaptive cruise set at 8-10mph over the indicated to allow for the optimistic speedo issue.

[DaveB]

My Range Rovers had adaptive cruise control. Spooky stuff but it worked once you learned to trust it.

Volvo have it as an option on most of their cars now as well. Test drove an SC60 with it a while back and your right, it is very weird. Especially when it speeds up without you telling it to when he car in front gets out of the way!

I didn't have the balls to test the collision prevention

[BoredBloke]

The variable ones do my fruit in! Last week on the M42 at 9pm they had 2 signs on slowing the traffic to 50 and then 40. There was nothing there - no accident, nothing!! All they did was slow an empty motorway down.

Quite often when I used to drive back on a Thursday night the variable speed thing would be set to 60 when the outside lane was empty due to the motorway being quiet. Are they on a timer?