So they are proposing a 60mph limit on the M1 between 28 and 35a to cut pollution.

http://www.bbc.co.uk/news/uk-politics-25619914

What do people think about this?

I use a small bit of this section (28-29) every day for my comumute and I am torn. I don’t want to be even slower to work but in reality there are very few mornings where I average over 60 due to congestion. And the lower speed limit should cut congestion.

And even if there is no congestion it will only add less than 3 mins to my journey time. (assuming I stick to the new limit which is a big assumption considering I don’t stick to the current one.)

And the lower speed limit should cut congestion.

Why?

and save a chuck of fuel too I imagine

rush hour speed limits are a joke anyway really

I was about to say you’d be lucky to average 60 anyway usually on much of the M1.

will it change anything other than the signs?

Why?

you get a lot less of that ‘mexican wave’ type of traffic where people accelerate towards slower moving cars and then over brake and a mile behind them the traffic all grinds to a halt 20 minutes later.

And the lower speed limit should cut congestion.
Why?

It’s very widely known and studied that lower maximum speeds result in smoother traffic and higher actual speed overall.

Why not just have a variable speed limit?

Can’t see the justification for making the speed limit 60mph at 7am on a Sunday morning

Why not just have a variable speed limit?

Infrastructure costs, I’d imagine. Plus disruption installing it all.

Makes so little difference to journey times, and saves a bunch of fuel. Why not?

The M6 has a managed/mandatory speed limit of 50mph from J10 to J13 and beyond.

During peak times it makes little difference to journey times because everyone is nose-to-tail anyway in a 51 mph freight train. what was the hard shoulder is simply another lane of lorries engaged in 10-mile overtakes it makes no difference to congestion

Outside peak times the mandatory 50 mph limit is both frustrating and rewarding. Frustrating because 50 mph on a fairly empty motorway feels as though you are barely moving and for short journeys the motorway is no quicker than going on the adjacent A-roads. Rewarding because you can sit with the cruise control at 51 mph and watch the mpg go to 99.9 mpg

Plus disruption installing it all.

They could do it now whilst there’s a 50mph limit as they’re changing all the central reservation.

wwaswas – Member

you get a lot less of that ‘mexican wave’ type of traffic where people accelerate towards slower moving cars and then over brake and a mile behind them the traffic all grinds to a halt 20 minutes later.

Why would a lower limit prompt a reduction in this behaviour?
An evidence for this?

Not trolling, just that speed limit v average speed isn’t something I’ve looked into before.

I’m for it, I don’t use the M1 😆

Infrastructure costs, I’d imagine. Plus disruption installing it all.

Motorways have signs in place already for adjusting speeds and other warnings on the fly.

Variable speed limits.. dear me.. a great idea ruined by mass stupidity 🙁

They spent ages putting one in around Newport, where congestion is bad, and everyone ignores it. We’re apparently too dim to realise why it’s there. People seem to stick to it on the M25 though.

Frustrating because 50 mph on a fairly empty motorway feels as though you are barely moving

The point about it being variable is that they switch it off when the motorway is fairly empty. Or they should, at least.

Both the Newport and Bristol sections on the M4 took years to install. I guess because the old signs didn’t support colour, so they couldn’t show the legally required red and white.

Motorways have signs in place already for adjusting speeds and other warnings on the fly.

having seen what they did on the M25 for variable speed limits it’s a lot more than just using the ‘fog’ signs during the rush hour to control speeds, though?

Why would a lower limit prompt a reduction in this behaviour?

because the difference in speed between slow and fast traffic is reduced. I don’t have specific documents but a quick google will show you empirical evidence that reducing maximum speed increases traffic flow beyond a certain vehicles/hour throughput on a give road.

Variable speed limits.. dear me.. a great idea ruined by mass stupidity

The areas I’ve travelled on where they’re used seem fairly successful, M42 going into Birmingham and bottom of the M1

Infrastructure costs, I’d imagine. Plus disruption installing it all.
Motorways have signs in place already for adjusting speeds and other warnings on the fly.

Yeah, they couldn’t just have a different speed limit than the rest of the network unless it was clearly signed at regular intervals – how else would they be able to enforce the limit?

wwaswas – Member

Why would a lower limit prompt a reduction in this behaviour?

because the difference in speed between slow and fast traffic is reduced. I don’t have specific documents but a quick google will show you empirical evidence that reducing maximum speed increases traffic flow beyond a certain vehicles/hour throughput on a give road.

Ta.
I’ll have a good look later.

I remember Newport when it was 70mph…I used to crawl through there at 10mph most mornings…now it’s 50mph most of the time, and everything flies through at 50mph. It’s way betterer than it used to be.

Problem at newport used to be high volumes joining motorway at slow speed…as wwaswas describes…the differential has been reduced now and everthing slips through better – still a lot of traffc but its usually moving well

I don’t think the variable signs at Newport are enforced yet though..plenty seem to go through at 70

Motorways have signs in place already for adjusting speeds and other warnings on the fly.

which everyone ignore. “50? Accident? Spray? Fog? Pffff! 80 is fine til I see a problem myself”

Mind you they also sometimes can’t be trusted, I’ve turned off a motorway warning of multiple lane closures and seen from the slip road a free flowing fully open motorway and run into a massive tailback caused by everyone else exiting the motorway.

Variable speed limits should be more widespread I reckon, evidence does seem to be that they shift a lot of traffic, driver perception is really not reliable.

Is there any research on banning lane changing too? Ie preventing lane hopping, reckon stopping that could improve throughput too

According to that article it’s a distance of 32 miles. SO by reducing the speed limit, assuming you covered that distance at the speed limit, the journey time will increase by about 4 and a half minutes. What a hardship

that’s BS. The thing that causes conjestion on motorways – the sort of conjestion where you are sat in a jam or slow moving traffic, for no apparent reason whatsoever, is peoples behaviours – primarily they travel too close to the car in front. This means they over-react to speed changes, hit their brakes too hard, causing the person to hit their brakes too hard, then accellarate away, which sets up a caterpillar motion of people braking harder and harder as you travel up the traffic flow until such time they brake to a halt.

If people could drive sensibly, leave a sensible amount of space between the car in front, then speed is not an issue and traffic flow would be nice and smooth and even.

Lowering the speed limit reduces this caterpillar effect, but doesn’t stop it and is treating the symptom and not the cause. Granted, the cause is something that is difficult to police and tackle.

Of course it doesn’t help that you have vehicles with different speed limits using the motorway – lorries limited to 56mph, towing vehicles limited to 60mph and normal cars traveling at a wide range of speeds. This just causes people to have to frequently adjust their speeds which just sets up the caterpillar effect.

wobbliscott – Member

Lowering the speed limit … is treating the symptom and not the cause.

isn’t the idea (in this case) to reduce air pollution?

Wobbliscot setting everyone at the same speed that everyone can achieve, ie 50 should help a lot, and of course at a slower uniform speed people can safely travel closer together and should be less fannying around.

Awhiles away with your hippy shit, no one cares, tell drivers traffic will be improved and you may get some support 🙂

Check your speedo accuracy with a GPS and you’ll probably find that 50mph actual is around 55mph indicated on your dash. So a cruise setting of ~56mph is probably still fine.

* probably! Most speedos over read by 10%

THere will be disruption because they are bound to want to install the money making machines to maximise the revenue making opportunities that reducung speed limits provides.

People are pillocks and don’t see there behaviour as having an affect on the rest of the traffic system and will continue to drive like tits because of their own self importance. I leave a gap of three car lengths in slow moving traffic so I can use my accelerator and clutch to control speed, only touching the breaks when deeming it necessary to stop, not slow down. I get twunts coming from behind me, under and overtaking and shooting round then into the space I’ve left and slam on. COCKS!

chrismac – Member
THere will be disruption because they are bound to want to install the money making machines to maximise the revenue making opportunities that reducung speed limits provides.

You forgot to mention the “War on Motorists!”

I wonder how much pollution will be cut by, and who will benefit from this reduced pollution. Is it surrounding built-up areas? Is there a weather system there that doesn’t remove pollution very well?

If people could drive sensibly, leave a sensible amount of space between the car in front, then speed is not an issue and traffic flow would be nice and smooth and even.

Agree to a certain extent – however it only reduces and will never remove the caterpillar effect. Even if traffic speed is slower and gaps are bigger, when a car in front slows – whether by braking or just lifting off the gas – the car behind takes a bit of time to register that this has happened. If they then apply the same amount of slowing, down to the same speed, the effect of the thinking delay is to close the gap on the car in front; so they need to actually slow down more in order to maintain the same gap, then speed up to maintain it. The car behind this one has the same effect except the slowing force is higher again. Multiply by dozens of repeats when traffic is essentially at the road capacity, and the cars at the back have to slow down to almost stop before starting again.

The trouble is twofold in my opinion – firstly, cars that see that it says 50 but insist on tailgating as if getting past makes any real difference. They make the gaps smaller, to the extreme case where thinking time is almost as much as the gap itself, and then need to jam on brakes to avoid a rear ender, means the number of cars to create a caterpillar effect is smaller. And more important, twunts who insist on driving in the outside lane nose to tail when there are two other (relatively) empty lanes that could be used so the outside lane isn’t rammed solid.

The biggest issue I reckon is that SOME people slow to 50mph but some insist on bombing through anyway, which causes no end of mayhem.

THere will be disruption because they are bound to want to install the money making machines to maximise the revenue making opportunities that reducung speed limits provides.

Can someone tell me why the police making money is a bad thing?

who will benefit from this reduced pollution.

Good question. This is all well and good for people who breathe air and live somewhere within the earth’s atmosphere, but what is it going to do for me?

wwaswas – Member
you get a lot less of that ‘mexican wave’ type of traffic where people accelerate towards slower moving cars and then over brake and a mile behind them the traffic all grinds to a halt 20 minutes later.

Why would a lower limit prompt a reduction in this behaviour?
An evidence for this?

Not trolling, just that speed limit v average speed isn’t something I’ve looked into before.

The best evidence would probably come from the M25 which is where I think this was first implemented. Its not just setting a limit but enforcing it rigourously. Bringing the speed down to the slowest road users – trucks basically – stops people switching lanes to pass slower traffic. Otherwise when the roads are busy people move lanes into smaller spaces, the car behind them dabs the brakes, the car behind them brakes harder – people see lights ahead so they all brake and the everyone just stops. Then pull away again into what is now an empty road – but now the traffic is even denser and expectant of another sudden halt again so even more likely to dab the brakes and it happens again. The lower speed limits have to be harshly policed as one or two drivers flouting there limit buggers it all up so they have to be pretty draconian.

The difficulty with any data derived though is while the experiments like the M25 have been running the traffic load has been increasing so an alleviation of congestion is being offset by more vehicles now being on the road.

I think it’s been known for about 40 years that you can’t alleviate congestion by building more roads…it doesn’t stop politicians from trying though.

I expect it was Cat Deeley who said Insanity is when you keep repeating the same experiment expecting different results…or something.

THere will be disruption because they are bound to want to install the money making machines to maximise the revenue making opportunities that reducung speed limits provides.

This has recently been implemented in the M62 Near Leeds/Bradford. It is a variable speed limit with Gatso cameras. It works brilliantly and has made a huge difference.

The key difference is the rigourous enforcement mentioned above.

I use the M25 quite a lot, well at least once every couple of weeks. Last night at around 11pm the signs were flashing 60 because of the rain/wind combo and I was in the slow lane (typical driving habit for me I’m afraid) to which near the exit for the A217 a Passat hacked on by with it’s drivers side tyre blown out and rubber flying everywhere.. so I caught up with him in the 50mph limit near Clackett in the roadworks and the blender was still driving along on the rim…at 50mph… I pulled back sharpish and we entertained ourselves watching from behind as the car swerved this way and that..

It was awful driving rain, so I understand why whoever it was didn’t want to get out and change it.. 😯

A fine piece of whataboutery.

I’ve always found the variable limits on the M25 to work well – but the ones on the M42 are often daft (suggesting a lowered speed when there’s not actually that much traffic, and actually creating congestion). It may be a difference in the times I use each one, but I think it’s a difference in implementation.

The difficulty with any data derived though is while the experiments like the M25 have been running the traffic load has been increasing so an alleviation of congestion is being offset by more vehicles now being on the road.

These schemes aren’t really aimed at reducing congestion though. The aim is to increase the capacity of the road in terms of cars per hour, and this certainly gets measured. And it works, hence the fact that managed motorways are being rolled out in lots of other places.