Variable Motorway Speed Limits

[squirrel_hunter]

I was travelling along the M4 recently and the Active Traffic Management section of it by Bristol that has the variable speed limits indicated by overhead gantry's. It was rush hours and I was expecting the hard shoulder to be open for use due to the heavy traffic. As I approached, the variable speed limits brought us down from 70mph to 60mph to 50mph as there was an "obstruction". The hard shoulder was marked as closed.

Just before reaching the "obstruction" which was a broken down vehicle on the hard shoulder traffic speed was further reduced, but this is where it got odd...

The hard shoulder was marked as closed. Lanes 3 and 2 were 40mph but lane 1 was 20mph.

After then passing the broken down vehicle the limits on all 3 lanes returned to 40mph and then 50mph. But the fact that there were different speed restrictions on the same carriageway and in the same direction at the same time to me was very odd. So what is the org's take on this?

[Bibio]

safety for people in the hard shoulder. the 20 was indicated just in case the person in the hard shoulder wandered into the traffic or to give the breakdown service personnel safety when dealing with the recovery.

[Red ones]

If you filtered could you do 30?

[squirrel_hunter]

I understand that it is for those working on the hard shoulder. However 20mph is a very low number when you consider the lane next to it is running at 40mph. Quite a difference. And this is what bothers me, particularly when it is enforced via fixed cameras...

[Red Herring]

Personally I think if you were to drive at 20mph on a free running live motorway lane you're likely to cause an incident when the first foreign lorry comes along and drives straight up your a......

[Specialone]

I live by the m42 where they first started using these things, they are a bloody pain tbh.
There is no consistency between them, you can go past one saying 60, next 40, then back up to 60, then 50, with no hazards obvious.

They are also slow reacting to things too, especially when the hazard has been cleared, sometimes taking over an hour.

I was on the m42 on Sunday morning at 9.30am and they were on for about a 5 mile section, going down to 40mph, it was very quiet so I just couldn't understand why, then in one gantries length it goes back up to national speed limit, so bloody frustrating.

[ophic]

Sometimes they say "warning - queueing traffic" along with a 40mph speed restriction, which is kind of a self fulfilling prophecy.

[andrewsmith]

Don't understand them in the slightest. Waiting for it to happen as part of the current A1 upgrade up here (not been mentioned, but its a prime area for it)

[Spank86]

The Idea is that they smooth out traffic flow and prevent queues caused both by hazards and by traffic congestion. So if an area ahead of you is getting congested they will slow you to 50 or 40 to keep things consistent.

Obviously it doesn't work but I'm not sure whether that's because everyone ignores it or simply because it doesn't work.

[PyroUK]

Little bit of both prob Spank

[Specialone]

Probably should add they certainly do work, especially when it's rush hour, it flows more and there is less braking which has that domino effect.

It's the over use of them I dislike.

[dizzyblonde]

The M62 has not benefitted from this stupid idea whatsoever. Especially around Leeds. Sometimes it feels like the traffic is permanently flowing at 20mph, naturally without the aid of the system in place.


Mind you, it has had a 50mph limit since around 2007 around Leeds and beyond.

[MisterTommyH]

Obviously it doesn't work but I'm not sure whether that's because everyone ignores it or simply because it doesn't work.

Actually it does.

The M42 is massively improved by the use of these during rush hour, as is the M6 from Walsall to Birmingham.

Yes it can get annoying when they are used on a weekend when there isn't a rush, but overall I'm in favour.

[SvNewbie]

I've heard the argument that they work so long as the operators leave the automated system to do its job. Apparently the problem is they have a hard time doing that.

No idea how true that is though. From what I've seen the locals know exactly which gantries have camera attached and race between them.

[Spank86]

Actually it does.

The M42 is massively improved by the use of these during rush hour, as is the M6 from Walsall to Birmingham.

Yes it can get annoying when they are used on a weekend when there isn't a rush, but overall I'm in favour.

I don't go on many roads that have them but whenever I have been on one I've either seen people completely ignoring the signs or been sat in a queue where 50mph is a pipe dream.

[scotty217]

I ride between j12 and 7 ( and return) for work on the m6. It seems to me that the problems with the gantries are two fold - first is drivers ignore them or have learnt where the cameras are- second is the operators don't leave it on auto and always seem to interfere. However the major flaw in this stretch is the fact that junctions 10 9 8 & 7 are all within about 5 miles and flood massive amounts of traffic onto the road. In fact 10 9 and 8 (for the m5) are within about a mile! They're having a laugh if they think that can be controlled. It's better but it's still shyt

[L3nny]

If people knew how to drive on a motorway and not hog the middle lane 2 inches from the car in front and lorries were restriced to the slow lane these variable limits wouldn't be necessary.

[Mrs DJ Fridge]

If people knew how to drive on a motorway and not hog the middle lane 2 inches from the car in front and lorries were restriced to the slow lane these variable limits wouldn't be necessary.

If lorries were only restricted to lane one this would lead to even slower traffic as they would all get stuck behind the Tesco lorries that can only do 50mph, Tesco claim that this is for the environment, it is not, it is just to reduce fuel costs. I often overtake cars im my lorry usually the cars are being driven by totally unaware older people, but you cannot ban them from the roads apparently.

[Grant66]

It'd only be slow in lane 1 though.
Other countries restrict slow vehicles to lane 1 during busy times and some ban lorries completely on Sundays.
What I still find amazing is that there is no compulsory training for driving on the motorway. If only people were taught how to drive on the motorway properly.

[L3nny]

If lorries were only restricted to lane one this would lead to even slower traffic as they would all get stuck behind the Tesco lorries that can only do 50mph, Tesco claim that this is for the environment, it is not, it is just to reduce fuel costs. I often overtake cars im my lorry usually the cars are being driven by totally unaware older people, but you cannot ban them from the roads apparently.

How fast does your lorry go then 53? 55? Does it really make that much difference and warrant the 5 minute overtake which takes up 2 thirds of the motorway for 4 miles.
I should add this would only be needed during busy times.

All of the Tesco trailers I see round here are towed by Stobart cabs anyway

[ophic]

Tesco claim that this is for the environment, it is not, it is just to reduce fuel costs.
Surely that amounts to exactly the same thing? Less fuel spent = less pollution
And how can you know their motivation?

[PyroUK]

Surely that amounts to exactly the same thing? Less fuel spent = less pollution

And how can you know their motivation?


I take it this way:

Saving money on fuel = greedy and an annoying inconvenience (the speed)

Protecting the environment = noble and acceptable.

Both the same thing as you say but worded differently gives a different view

[ophic]

Both the same thing as you say but worded differently gives a different view
So no-one can really claim it was done for one reason or another.

[Spank86]

So no-one can really claim it was done for one reason or another.
TESCO could. :D

[PyroUK]

So no-one can really claim it was done for one reason or another.


Well yeah it's semantics essentially.

[Specialone]

Don't be fooled by any crap any big company comes out with regarding their environmental responsibilities etc, they are driven purely on profit, bottom line, if it cost more money/fuel to limit their wagons at 50mph, they wouldn't do it, environment friendly or not.

It's just used as a marketing tool, but if it's expensive they won't take any notice of the environment.

[ophic]

Profit or image, where image leads to profit. Sometimes you can do the right thing for entirely selfish reasons.

[Mrs DJ Fridge]

How fast does your lorry go then 53? 55? Does it really make that much difference and warrant the 5 minute overtake which takes up 2 thirds of the motorway for 4 miles.
I should add this would only be needed during busy times.

All of the Tesco trailers I see round here are towed by Stobart cabs anyway

56, approx 15 seconds to get past Tesco lorry

[Spank86]

56, approx 15 seconds to get past Tesco lorry

Even less to get round the bloke I saw today going about 45 on the M3.

Can't really expect a lorry to stay behind that.

[Matt-EUC]

They're the ones who need arresting. Not those doing 80.


Sent via the medium of interpretive dance.

[Sir Trev]

I now have the joy of six junctions of the M25 on my commute. I frequently find people drifting along at 50 in lane 1 but they're easy to avoid as most of the remaining traffic is in lanes three and four all two feet from each other. Keep to lane 1 yourself and you can undertake hundreds of people at a time.


Quite surprised we don't have middle-lane cams yet to enforce the lane-hogging and tail-gaiting offences, especially as there is a LOT of fines to be made from them.


Coming home the variable limits on the M25 usually kick in for the last few junctions down to the M40 turn. They don't really work as nobody heeds them from what I have seen.

[Matt-EUC]

I think the main problem is that most people ignore them but some take them for gospel and slam on their brakes before each one, causing accidents and several hours of the domino effect.


Sent via the medium of interpretive dance.

[Bluepete]

My experience of Managed Motorways is positive.

I've just come home from Lyme Regis and the sections of the M5 and M6 that have variable speed limits were VERY congested, but flowed constantly at 50mph. In the years prior to the system being put in place, those areas were always massive no-go zones.

The M60 is due an upgrade to managed status from Simister at the M60/M62 junction to around the Trafford Centre in the next year or so. No doubt, I'll gain more experience of the foibles of the system then.

And Matt-EUC, in nearly seventeen years as a Cop in Manchester, I've never arrested anyone for driving at 80mph on a motorway.

Pete ;)

[MisterTommyH]

Wonder if there's something geographical about it then..... Or something about the mentality of the drivers in different areas?

myself, SP1 and bluepete all agree that the ones round here work.... And even scotty agrees that they're better (unfortunately we can't redistribute all the junctions).

What is it that makes the ones in the midlands work but not the others?

Is it that we've had it so bad for years that we see the benefit.... And the benefit elsewhere is less noticeable? Or is there something else?

[Bluepete]

I think you might be onto something there MTH. I always love driving around in Dorset and East Devon. It's sloooooow and relaxing, there seems to be no stress. The Midlands to me are where I grew up, and seem quite chilled too.

The North, around M'cr is so fraught and full of Feck-You attitude that I'm sure the M60 managed system will have trouble.

The M25 circuit is, of course, modelled on the dark sigil Odegra, so can only lead to doom and despair. In reality, all we ever hear about on the radio is "M25 doom" "M25 queue" "M25 end of the world" I suppose it's a matter of pressure and volume of traffic.

Every area has a feeling to it. Each City has an identity. Sometimes it's cooperative, sometimes it isn't.

Pete ;)

[Spank86]

.

The M25 circuit is, of course, modelled on the dark sigil Odegra, so can only lead to doom and despair.

Love it.

Good omens.

[atassiedevil]

"Hail the great beast, devourer of worlds...."

[Specialone]

Was on the m42 again on Sunday, quite quiet, after 5 mins of being on there, 60mph speed flashing, it lasted 3 gantries before going back to NSL, wtf? No obstructions, nothing, It's this type of thing that I hate about them.

[MisterTommyH]

I'm not so sure about these now. For the second time this month I passed cars stopped on the 'hard shoulder' while the gantries were still showing it as a live lane. I have no problem with the principle, but surely it's only safe if there is a constant watch to close the lane when someone stops.

[ophic]

Is this where the hard shoulder is used as an extra driving lane?

[MisterTommyH]

Yup

[Sir Trev]

I know you don't get that many breakdowns on motorways these days but using the shoulder as a live lane is crackers in my book. I've had a puncture and several other reasons to use them over the years and they are vital for safety.

[ophic]

Free flowing motorways, seems nuts, agreed. Where there's queueing traffic that doesn't go very fast, perhaps it's a viable idea.

But if the motorway wasn't congested, there'd be no need to use the hard shoulder anyway. Hence the signs that tell you whether you can use it or not.