RE: 50 limits by the back door: PH Blog

[Engineer792]

saaby93 said:

Engineer792 said:

Do you know how they work....?

Do you mean how they 'should' work

How they're supposed to work

[Kenny Powers]

rampageturke said:

The main problem I see with smart motorways is they keep putting them in and telling nobody how they work. So people just see a lower 50 limit for what they think is absolutely nothing, then start seeing red like a bull and continue to do 70 then hit the congestion and complain when they don't work.

This is a good point that I think I touched on earlier in the discussion. Along the lines of public information programmes. But I'm now not so sure it would be worth the expense. Savvy driving enthusiasts have had it explained to them over and over and over and over in this discussion, and they still don't get it. I don't hold much hope for the rest of the driving public.

[FiF]

I'd agree there are too many types of motorway. For example, the M42 where the extra lane is only to get used when signed and is effectively only for use by those wishing to exit at the next junction. Then compare this with the M1 section under discussion, ie Jn25 up to Jn35, where apart from Tinsley viaduct is now 4 full time lanes, plus refuges, all coming not long after the section near Donington Kegworth jn24ish, which is 4 full time lanes and a hard shoulder.

Also sympathise with the view that too many motorists can't even get the very basic stuff right, like driving without needing to look at Instafacetweet constantly.

[macscrooge]

I use this bit of M1 often and I have to agree with the tone of the original post. The speed limits and warnings rarely seem to have any justification in reality.
I should point out that I'm no boy racer - but a middle aged git - but I have come to dread any journey which involves this stretch of road.

[big_rob_sydney]

Mandown46 said:

Big Rob, I feel like I've completely lost the train of that part of the discussion

What is it you would actually want to see happen? within what is reasonable of course (we all have our dream scenarios)

If there are no people working (eg on weekends), then remove the signs saying "workmen ahead." Use the electronic signage where possible.

People have been talking up this technology for a long time now, and yet we STILL have to sit at 50mph being told "workmen ahead", when there isn't a soul in sight. If we have the technology, use it. This is very cheap.

I used to work in operations, and we used to have start of day and end of day procedures. Its not hard to remove signs for the weekend, should the tech not be available. This is more expensive than triggering a technical solution, sure. But the point is it can be done, and collecting a few road signs on a 2-3 mile stretch of roadway isnt overly difficult, nor is it overly resource consuming.

[saaby93]

Mandown46 said:

In the long term works, like widening, or building new junctions or upgrading to smart motorways, the electronic signs will get decommissioned as soon as they start digging. New ones are amongst the last things to get put up prior to opening.

If its sections where narrow lanes and the varioguard is installed, that's not easy to take down, and remember that although you might not see many roadworkers, there are still recovery operators, Police and Traffic Officers working in the road, as well as works safety officers doing the rounds making sure nothing has been stolen, and everything, cones, signs and barrier wise is still where they should be.

There is a general push to get more of the portable VMS boards, but to be honest, they are less than useless.


Hopefully, in future there will be a limit to the distance of works, I believe the intent is to cap it at 2km, in order to try and reduce motorists frustrations. I don't know how that will be applied to the big schemes, whether it will increase the overall time and amount of roadworks.

I don't know if there is a simple fix, that both solves the frustrations of long sections of 50mph works (believe me, I've spent a lot of years driving the same stretches) but at the same time doesn't increase the danger to worker, traffic officers, recovery operators and motorists themselves.

Theyre not long sections of works - theyre long sections of non -works
Why does this keep turning into an apples and pears discussion?

Someone says there are 50( or less signs on gantries on motorways where there are no roadworks for no apparent reason
Someone replies saying the signs are needed for narrow lane running
Someone says why are there 50 signs where there are cones on the hard shoulder, no working and no narrow lanes
Someone replies it's too difficult to switch off the 50 signs

Whats being complained about looks easily solvable
Lets not mix it up with whats not being complained about

[FiF]

Precisely saaby, we get the roadworks and narrow lanes argument, it's the random speed changes when there are no apparent hazards, or hazards which have long gone, or the variability of the limit set which are the issues which harm the general regard for these systems.

And with poor opinions out there then you get an element jamming through red X lane closed signs towards workers in the carriageway which is really undesirable.

[FiF]

So no answers then. Just like ringing up the Highways hotline to report something amiss. Brrrr brrrr brrrr brrrr .... Long time later brrrr brrrr. Nobody at home.

[LukeBird]

Could not agree more Dan.
I completely get the 'trust' element too, I think we could slip down a slippery slope if that sort of thing becomes more prevalent. Speed cameras littering the place causing exactly the same issues.

[Blakewater]

Engineer792 said:

saaby93 said:

Engineer792 said:

Do you know how they work....?

Do you mean how they 'should' work

How they're supposed to work

There seem to be two contradicting ideas about how they're supposed to work.

One idea is that if traffic is starting to bunch up, reduced speed limits further back prevent people speeding up to the building congestion, slamming on the brakes and causing a wave braking effect that turns a little bit of mounting traffic into a massive tailback.

The other is that lower speeds allow people to travel closed together with smaller gaps between vehicles, thereby increasing capacity.

Surely the latter requires people to catch up to the traffic in front, which overrules the former idea, and also results in the wave braking as people traveling more slowly than they would like on the motorway tend to drive too close together and brake tap all the time.

If it can be statistically proven that smart motorways have increased throughput, can anyone prove that the variable speed limits and cameras have made a positive difference and not just the provision of an extra lane?

It also seems pretty odd that, even though motorways were first built before there was a national speed limit, everything is tested and built with vehicles traveling at the current speed limit being the absolute maximum tolerance. It's a pretty poor system that doesn't ensure people are safe if someone does exceed the speed limit or have a brake failure or allow for future governments to increase the speed limit. When an 80mph limit was proposed in Parliament it was a clear, specific acknowledgement that a great many normal people drive at that speed everyday without being swivel eyed lunatics and killing everybody. In every other design and test scenario equipment is tested to withstand situations well beyond what is expected of normal everyday use so there is a huge safety margin.

Edited by Blakewater on Thursday 6th April 07:52

[Engineer792]

Blakewater said:

Engineer792 said:

saaby93 said:

Engineer792 said:

Do you know how they work....?

Do you mean how they 'should' work

How they're supposed to work

There seem to be two contradicting ideas about how they're supposed to work.

One idea is that if traffic is starting to bunch up, reduced speed limits further back prevent people speeding up to the building congestion, slamming on the brakes and causing a wave braking effect that turns a little bit of mounting traffic into a massive tailback.

The other is that lower speeds allow people to travel closed together with smaller gaps between vehicles, thereby increasing capacity.

Surely the latter requires people to catch up to the traffic in front, which overrules the former idea, and also results in the wave braking as people traveling more slowly than they would like on the motorway tend to drive too close together and brake tap all the time.

If it can be statistically proven that smart motorways have increased throughput, can anyone prove that the variable speed limits and cameras have made a positive difference and not just the provision of an extra lane?

It also seems pretty odd that, even though motorways were first built before there was a national speed limit, everything is tested and built with vehicles traveling at the current speed limit being the absolute maximum tolerance. It's a pretty poor system that doesn't ensure people are safe if someone does exceed the speed limit or have a brake failure or allow for future governments to increase the speed limit. When an 80mph limit was proposed in Parliament it was a clear, specific acknowledgement that a great many normal people drive at that speed everyday without being swivel eyed lunatics and killing everybody. In every other design and test scenario equipment is tested to withstand situations well beyond what is expected of normal everyday use so there is a huge safety margin.

Edited by Blakewater on Thursday 6th April 07:52

Yes, it doesn't make much sense when you start scratching the surface.

With little more than hand-waving being offered up by way of explanation, it would seem that few, if any, people know how they're really supposed to work.

I have found precious little literature on the subject, and the bit I have found deals mainly with generalised flow and wave theory, with little or nothing by way of translation to practical application - certainly nowhere near enough to convince me to spend untold millions in taxpayer's money if I was a politician.

Edited for typo

Edited by Engineer792 on Thursday 6th April 13:47

[techguyone]

Smart motorways is simply a precursor to PAYG no doubt, watch this space and we'll see.

[DJT]

I assume that part of the business case was that the number of accidents was lower, or at least less severe, than when previously a dumb motorway. So perhaps an unreasonably slow speed limit for the foreseeable future will help them prove that they were correct and bonuses should be paid.

[Engineer792]

DJT said:

I assume that part of the business case was that the number of accidents was lower, or at least less severe, than when previously a dumb motorway. So perhaps an unreasonably slow speed limit for the foreseeable future will help them prove that they were correct and bonuses should be paid.

If that was the case, why keep it secret?

[saaby93]

DJT said:

I assume that part of the business case was that the number of accidents was lower, or at least less severe, than when previously a dumb motorway.

If youve seen that anywhere as a business case, please post it up

There is a case that the Highways Agency/England are trying to reduce congestion - it costs the country a fortune. So you can see why if they put these things in say at the M5 M6 junction it makes merging easier and reduces congestion that's great.
If its an empty motorway at night and patently makes no difference - what's the point?

Some authorities will say how many millions or revenue they gain for 'road safety' purposes when the cameras and limits are in place.
Aside from why theyre in place, are there many people that dont know how the cameras work?

[easyhome]

Perfect example today, 14:45 between J5 and 6 on the coast bound M20.

Light traffic and the gantry signs come on saying "Caution Queue". I'm only doing 70 anyway so I carry on, no sign of anything. The next gantry is showing 40mph! Luckily no one behind me so I brake hard down to 40, still no traffic, the next gantry is showing NSL.

Now, from some of the answers given previously I understand that this was possibly caused by a slow lorry, maybe a faulty sensor but to my inexpert eyes it seems that any system which can go from 70 to 40 like that is dangerous and certainly not fit for purpose.

James

[NeilC M3]

When Highways choose to enforce the gantry signs correctly they are definitely beneficial. But when speed limits are applied and other signage warn of traffic problems when there are none, it makes a mockery of the whole system, making it an expensive failure!! Step up Highways!

[Kenny Powers]

Perhaps the signs should say "there are traffic problems, but because we are limiting your speed, the road ahead will be clear by the time you get there, so stop your whining"?

Might be a bit distracting though

[Mr Tidy]

Kenny Powers said:

Perhaps the signs should say "there are traffic problems, but because we are limiting your speed, the road ahead will be clear by the time you get there, so stop your whining"?

Might be a bit distracting though

Slight revision based upon my regular experience of the M25 from J12 to J10 "there are traffic problems that we created by posting a lower limit to bunch traffic up, but shortly after J11 the road will be clear because then you can return to the NSL"!

[SBDJ]

Kenny Powers said:

Perhaps the signs should say "there are traffic problems, but because we are limiting your speed, the road ahead will be clear by the time you get there, so stop your whining"?

Might be a bit distracting though

Did you invent the system or something? You seem very defensive of it, despite the admission by someone who works for the HA earlier in the thread that it does get things wrong resulting in random lower speed limits. The traffic queue explanation doesn't always fit. Seems a couple of slow moving lorries can result in a drop to 40mph for everyone else further back.