Motorway lower speed limit trial

[EmilysDad]

...

Mind you, as I cruise along at about 72 I am frequently overtaken - it's interesting how some of the time it's Mr White Van Man and I'll see him braking before he gets to the camera but there are lots of people who just fly by. I do wonder how many of them are being ticketted...

I think the same when doing 52/53 in a 50 limit due to road works and frequently get overtaken.
Then there are always those that insist on doing 49.9 mph in the middle lane and refuse to move left ..... arggghh!

 

[bembo449]

how they decide that motor vehicles are the route of all evil is beyond me , pretty sure us motorists will get to foot the bill when they try to recoup the losses from the Covid too

 

[AnthonyUK]

I too fear that this is to a great extent a revenue raising exercise.

If these areas have high NO2 due to traffic pollution then surely electric vehicles should be exempt to the reduction in speed limit.

NJSS

You could argue the case for petrol cars too. Ban diesels from the outside lane

 

[sl500amgsport]

Pollution is a factor of how much fuel is being used opposed to how long the vehicle spends on a road.

Travelling at 80mph and achieving 35mpg you will leave 70% more pollution per mile than if you had been travelling 50mph and achieving 60mpg. How long you spend on that road makes no difference

We really are making an utter mess of our planet and one of the many factors is our use of fossil fuels and we do need to start using them a little more sparingly. Of course I do see the futility in trying to be a little more economical in the face of the ridiculous over population of the planet....

With a 4.7l V8 there is very little mpg difference between 60mph and 80mph, in 7th you are still only doing around 2000rpm where as in a 2l it is nearer to 3000rpm.



Mercedes SL500 R231

 

[Blobcat]

With a 4.7l V8 there is very little mpg difference between 60mph and 80mph, in 7th you are still only doing around 2000rpm where as in a 2l it is nearer to 3000rpm.



Mercedes SL500 R231

My W213 “tool-eater” was ~1,250 revs at 70...

 

[Craiglxviii]

With a 4.7l V8 there is very little mpg difference between 60mph and 80mph, in 7th you are still only doing around 2000rpm where as in a 2l it is nearer to 3000rpm.
Mercedes SL500 R231

it’s actually the same argument with supersonic passenger aeroplanes. The faster they go on a given power installation, the less time in the air, the less pollution caused.

 

[badger_wazzala]

All the Green Deal provided was long-term debt for home-owners and difficulty selling their homes with a secured debt on the property. It did generate lots of taxable income for the government though...............

I thought the Nazis lost the war?

Sorry, I read the gov.uk report referenced earlier in the thread.

 

[Doors]

Define “pollution” please. CO2? NOx? Particulates? Which particulates?

I don’t mean this to derive into an anthropogenic climate change argument, however there is plenty of evidence to show that the planet is entering a warming phase as part of its long term climate cycle.

Right now we have more fossil fuel available to us than we have ever had before, and our ability to discover and recover them economically is improving each year.

The planet isn’t overpopulated. All projections point to the planetary population peaking at ~9bn in the late 2100s and reducing markedly in the two centuries beyond that. The infrastructure already in place or planned can likely support that level of population.

The official IPCC report- not the media reports of it- is eye opening. It’s worth reading. It promotes more rearing of meat herds, increased nuclear and clean gas power generation, removal of wood & pellet burning stoves and coal burning forms of transport & power generation. It also assigns a nominal- only factor to the global automotive fleet in terms of contribution.

Which ever pollution you wish to highlight, in free flowing traffic it will go up per mile with increase of speed.

For me climate change arguments went out about a decade ago, man made climate change denial seems to fit nicely alongside 5G being responsible for Covid.

True that we are no where near peak oil, but from now on in ts extraction and processing will be increasingly environmentally damaging. And even if it wasn't, considering the damage we now know it causes we really do need to start to move away form it as soon as possible.

The planet is grossly over populated, we are currently using our resources 60% above a long term sustainable manner.
https://www.footprintnetwork.org/our-work/ecological-footprint/
And bear in mind the damage that has been done so far is by less than a one billion of us, and the other 6 billion are desperately trying to adopt our livestyles. If all 7½ billion of us enjoyed the lifestyles we have in the UK, we would need another 5 planets to provide a long term sustainable future! Another couple of billion people is the very last thing we need right now.

We are currently wiping our our ecosystems at an alarming rate, and even if you don't accept the moral argument that this is a bad idea, then you do need to accept that wiping out what we fundamentally rely upon is beyond crazy.

 

[sl500amgsport]

****** 5G, went back to using 4g and so far Covid free! ;-).

Mercedes SL500 R231

 

[Craiglxviii]

Which ever pollution you wish to highlight, in free flowing traffic it will go up per mile with increase of speed.

For me climate change arguments went out about a decade ago, man made climate change denial seems to fit nicely alongside 5G being responsible for Covid.

True that we are no where near peak oil, but from now on in ts extraction and processing will be increasingly environmentally damaging. And even if it wasn't, considering the damage we now know it causes we really do need to start to move away form it as soon as possible.

The planet is grossly over populated, we are currently using our resources 60% above a long term sustainable manner.
https://www.footprintnetwork.org/our-work/ecological-footprint/
And bear in mind the damage that has been done so far is by less than a one billion of us, and the other 6 billion are desperately trying to adopt our livestyles. If all 7½ billion of us enjoyed the lifestyles we have in the UK, we would need another 5 planets to provide a long term sustainable future! Another couple of billion people is the very last thing we need right now.

We are currently wiping our our ecosystems at an alarming rate, and even if you don't accept the moral argument that this is a bad idea, then you do need to accept that wiping out what we fundamentally rely upon is beyond crazy.

No, that doesn’t stack up. In free flowing traffic any emissions will increase roughly proportionately with engine loading and revolutions. The difference between 60 and 70mph in a modern 9G box is around 150-200rpm, or 8%. But that 8% corresponds to a 15% reduction in time spent on the road....... which therefore reduces the emissions increase to around 4%.
This isn’t linear however, due to aero effects everything changes above 45-50mph. So the argument purely in terms of efficiency of emissions should be to keep everything moving in as high a gear/ lowest engine loading & revs as poss at just under 50mph, or as well designed as possible, as free flowing as possible and as fast as possible above 70mph.

The official line is that climate change is man- made. Ok, I’m not really arguing that; the point is the delta between a man- made climate change and any previous warming/ cooling cycles the planet has experienced.

Why will oil extraction “from now on” become increasingly more damaging to the environment? More damaging than open cast mining, or indeed mining of any kind in countries with laxer environmental controls than western nations would impose?
It was only 5 years ago that scientists were finally able to prove that oil is a (potentially) finite resource; interestingly what they still do not know is the rate at which it can be reformed. A number of wells previously capped due to exhaustion have been reopened to find levels at 20-30% for standard extraction techniques. No one has much of an idea why, save that oil is percolating one from <somewhere>. One mainstream theory is that oil formation from biomatter doesn’t take millions of years, but hundreds or low thousands. Regardless, we can now grow direct- biofuel- producing algae in industrial volume so oil recovery may well become a non problem in the next few decades.

Your supposition of needing another 5 planets doesn’t stack up with the official research on this done by the IPCC and the UN. Both of those agree that the least disruptive, cleanest and best thing for the planet is to help make every nation as rich as possible as quickly as possible; the wealthier individuals are, the more/ easier choices they have to be more environmentally friendly at the lowest possible level (individual household).

I’ll say it again. The planet is not grossly overpopulated. Go to the same IPCC report. The global population will continue to rise until it hits the 9bn mark- not the 12-15bn reported by news media- at which point it will rapidly decline. Most of the increase will be in north/ eastern Latin America and sub Saharan Africa. China has 80 years left before its population imbalance decimates its people, hence why they’re rapidly trying to carve out higher added value & innovative industries now than leaving it until it’s too late.

Absolutely wiping out the natural environment is A Bad Thing. Which is why it’s interesting to take the hype out of things and look at the actual data; the level of primary deforestation is pretty closely matched by the level of secondary REforestation, with around a 3 year gap. I know that doesn’t address the whole picture and there’s more to it than just the rainforests, but over the last 20-30 years more has been done- and as society becomes wealthier, ever yet more can continue to be done- to arrest environmental decline and begin improvements. Wetlands conservation, anti poaching patrols across the Savannah, whatever.

 

[pgh13]

https://www.google.com/amp/s/www.bbc.co.uk/news/amp/uk-england-54130862
Thoughts?

Thin end of yet another wedge, ostensibly, on the grounds of environment/safety/Covid (delete as required) to raise more revenue.
P.S. and if you saw the wide strip of countryside being laid waste for HS2 preparation work (they haven't started the f....g thing yet) can't help thinking that the government would concrete over it all for 50p

 

[Timeandleisure]

Thin end of yet another wedge, ostensibly, on the grounds of environment/safety/Covid (delete as required) to raise more revenue.
P.S. and if you saw the wide strip of countryside being laid waste for HS2 preparation work (they haven't started the f....g thing yet) can't help thinking that the government would concrete over it all for 50p

Perhaps this is to pay for HS2 so it can get going again in time for the next election campaign.....

Wonder what the hypothesis of this trial is exactly...?

 

[pgh13]

Perhaps this is to pay for HS2 so it can get going again in time for the next election campaign.....

Get real! it's a government project, maybe ready for the election after next. Lots more tax increases to come to cover the overspend on it!

 

[Doors]

No, that doesn’t stack up. In free flowing traffic any emissions will increase roughly proportionately with engine loading and revolutions. The difference between 60 and 70mph in a modern 9G box is around 150-200rpm, or 8%. But that 8% corresponds to a 15% reduction in time spent on the road....... which therefore reduces the emissions increase to around 4%.
This isn’t linear however, due to aero effects everything changes above 45-50mph. So the argument purely in terms of efficiency of emissions should be to keep everything moving in as high a gear/ lowest engine loading & revs as poss at just under 50mph, or as well designed as possible, as free flowing as possible and as fast as possible above 70mph.

The official line is that climate change is man- made. Ok, I’m not really arguing that; the point is the delta between a man- made climate change and any previous warming/ cooling cycles the planet has experienced.

Why will oil extraction “from now on” become increasingly more damaging to the environment? More damaging than open cast mining, or indeed mining of any kind in countries with laxer environmental controls than western nations would impose?
It was only 5 years ago that scientists were finally able to prove that oil is a (potentially) finite resource; interestingly what they still do not know is the rate at which it can be reformed. A number of wells previously capped due to exhaustion have been reopened to find levels at 20-30% for standard extraction techniques. No one has much of an idea why, save that oil is percolating one from <somewhere>. One mainstream theory is that oil formation from biomatter doesn’t take millions of years, but hundreds or low thousands. Regardless, we can now grow direct- biofuel- producing algae in industrial volume so oil recovery may well become a non problem in the next few decades.

Your supposition of needing another 5 planets doesn’t stack up with the official research on this done by the IPCC and the UN. Both of those agree that the least disruptive, cleanest and best thing for the planet is to help make every nation as rich as possible as quickly as possible; the wealthier individuals are, the more/ easier choices they have to be more environmentally friendly at the lowest possible level (individual household).

I’ll say it again. The planet is not grossly overpopulated. Go to the same IPCC report. The global population will continue to rise until it hits the 9bn mark- not the 12-15bn reported by news media- at which point it will rapidly decline. Most of the increase will be in north/ eastern Latin America and sub Saharan Africa. China has 80 years left before its population imbalance decimates its people, hence why they’re rapidly trying to carve out higher added value & innovative industries now than leaving it until it’s too late.

Absolutely wiping out the natural environment is A Bad Thing. Which is why it’s interesting to take the hype out of things and look at the actual data; the level of primary deforestation is pretty closely matched by the level of secondary REforestation, with around a 3 year gap. I know that doesn’t address the whole picture and there’s more to it than just the rainforests, but over the last 20-30 years more has been done- and as society becomes wealthier, ever yet more can continue to be done- to arrest environmental decline and begin improvements. Wetlands conservation, anti poaching patrols across the Savannah, whatever.

Do you honestly believe that rpm has such a direct link with fuel economy? gears are there to keep the engine at its most efficient rpm, increasing the gearing will load the engine more and it will use more fuel for the same rpm. At the end of the day it is just straight forward basic physic, from 60 to 70 mph wind resistance will increase by 36%, at around 60mph overcoming air resistance accounts for about 40% of energy (40% rolling resistance and 20% wastage) Therefor expect fuel economy to increase by around 14% for that increase in speed. The time taken makes no difference to mpg or pollution per mile.


Natural warming cooling of the planet has always taken many millennia, we are now experiencing similar changes in decades

Oil is becoming increasingly difficult to extract, one barrel of energy once produced 50 barrels of oil, in a few hundred years we may be left with the likes of the Canadian Oil Tar Sands whre it takes around 36 barrels to produce 37.

Could you point me to this IPCC data?

Any reference to this reforestation? I know governments have been promising billions of trees, but what government promises and what is delivered can be tow entirely different things

 

[Timeandleisure]

Get real! it's a government project, maybe ready for the election after next. Lots more tax increases to come to cover the overspend on it!

You’re optimistic! That’s great news

 

[d215yq]

Perhaps an old diesel is not the same as a new one but to calculate fuel use you calculate MPG - the clues in the unit - there is no need nor merit in introducing the "time on the road" element. I drive long trips on empty Spanish motorways and nice continental A roads where I can do a tank to tank with only about 1 mile of start stop driving and the remainign 600 miles at cruising speed. The real world results, which have been repeated many times using tank to tank fill ups and google maps as the distance measure are as follows:

Intended 55mph cruise speed (realistically 50-55 cruise speed (I only achieve this on A roads as wouldn't drive this slow on empty motorways so it includes the odd roundabout or mountain part and junctions that reduces efficiency) - 56mpg (extrapolating a constant 55 would likely get 60mpg if there were zero hills/junctions/roundabouts etc

65 cruise speed (relaistically non stop motorway driving between 60 and 70) - 54mpg

75 cruise speed (speed limit in Spain but realistically non stop motorway driving 70-75) - 47mpg

I did once do French motorways on a tankful at a constant 80 but as it wasn't repeatable, was cold and I had 3 passengers and luggage I won't include it, but I only managed 43mpg despite not ever braking nor leaving the autoroute the whole journey!

If you look at manufacturer stats it's the same thing. Cars efficiency is peak when it is comfortable in 5th gear (mostly 45-55mph depending on the car) and will tail off exponentially with increased speed.

I'm not necessarily advocating a reduced speed limit on a motorway (personally I think it is better to massively reduce cars in cities and pedestrianise/cycle lane over roads in city centres as that is where cars pollute most (and cause other negatives like noise, take up space, etc), the pollution causes the most problems and there are more alternatives. But it cannot be disputed that if all cars drove at 60 instead of 70 on motorways fuel use, C=2, NOx etc would all be reduced.

 

[SL63 Mark]

I know I am not setting a good example with my 5.4 litre V8, but I do try to do my bit for the planet. I now only drive into work 2 days a week instead of 5, which is one good thing to come out of COVID.

We have a more economical car, but the Merc always comes out on a Sunny day.

I think people need to travel less, sorry I really do. Foreign holidays, airline and ship leisure travel and chucking plastic in the sea really get my goat. Loss of Biodiversity is horrendous in the UK and elsewhere.

There was a video of the sea floor in the Marianas trench or somewhere, 7 miles under the ocean, and guess what, there was some plastic in shot and a plastic office chair.

Horrible.

 

[Craiglxviii]

Do you honestly believe that rpm has such a direct link with fuel economy? gears are there to keep the engine at its most efficient rpm, increasing the gearing will load the engine more and it will use more fuel for the same rpm. At the end of the day it is just straight forward basic physic, from 60 to 70 mph wind resistance will increase by 36%, at around 60mph overcoming air resistance accounts for about 40% of energy (40% rolling resistance and 20% wastage) Therefor expect fuel economy to increase by around 14% for that increase in speed. The time taken makes no difference to mpg or pollution per mile.


Natural warming cooling of the planet has always taken many millennia, we are now experiencing similar changes in decades

Oil is becoming increasingly difficult to extract, one barrel of energy once produced 50 barrels of oil, in a few hundred years we may be left with the likes of the Canadian Oil Tar Sands whre it takes around 36 barrels to produce 37.

Could you point me to this IPCC data?

Any reference to this reforestation? I know governments have been promising billions of trees, but what government promises and what is delivered can be tow entirely different things

Ok. Fuel injectors deliver a fixed amount per shot. Increase the frequency of those shots by increasing the rate of revolutions per unit time and therefore more fuel is used. The more heavily loaded a powertrain is, the more stress (ok, technically strain) is placed on it and therefore more quickly it’s internal lubricating and transmissions fluids are consumed.

Wind resistance from 60 to 70mph doesn’t increase by 36% in the real world. The aerodynamics of modern cars are tuned pretty well to peak efficiency at modern motorway speed limits. So, wind resistance is broken down into a number of factors, in no particular order these are:

block coefficient (the size of hole needing to be punched through the air).
Skin friction, directly proportional to wetted area.
Rate of change of profile.
Stagnation zones.
Parasitic drag.

Then there are road friction, powertrain losses and aero: noise effect losses to account for.

Air is a strange fluid to move through. It takes more energy to get up to a speed (any speed) above the aero effect boundary than it does to stay there. Then, taking all of the points above:
A low, narrow car has to bore a smaller hole than a tall, fat one.
A car with low rate of change of shape (long and pointy) pushes air more efficiently out of the way than a short and fat one.
A car with smaller surface area is less subject to skin friction and, higher in the speed regime, parasitic drag, than one with more surface area (this directly contradicts the long & pointy issue btw).
A car with poorly designed transition zones can leave stagnation areas, where the air rolls like a comber on a beach and attempts to suck the car backwards.

The undersides of cars used to get zero attention, now they have all sorts of aero channels to reduce or eliminate topside aero problems. Those funny shaped wheel arches contribute useful percentages of aero efficiency improvements.

Add all that together and we arrive at (generally) long, low, smooth & sleek cars being the best at aero, however costing significantly more in materials and labour than small, rounded or flattish sided vehicles so therefore being less efficient to manufacture.

None of this is basic physics either..!

So, we then get to the argument: what is best to reduce fuel burn? Well, burning the least amount of fuel per mile of course. So it follows, one can theoretically design a long, low, sleek vehicle with a given engine that, on a straight flat road, for the mass of that car and for a given drivetrain setup, will produce engine revolutions and therefore fuel burn per unit time that equal the fuel burn of a short, fat vehicle at a lower speed. The issue then includes controlling the total units of time that such a car spends on the road, which is determined by its speed. The time taken makes no difference the emissions per mile, but then conversely the emissions per mile also make no difference to the total emissions per journey if the journey takes 15-20% longer in time for a car optimised for a higher cruising speed.

Natural warming and cooling has not always taken millennia, there was a cooling period that took around 2 centuries late in the first millennium that lasted to, well, around now; also there was one around the third millennium BC that again took in the order of several centuries start to finish to begin and then revert back.

You do realise that Peak Oil as a theory has long since been exploded? Oils sands and shales cost more to recover due to the economies of scale of the kit utilised; the infrastructure for a deep sea rig system is enormous in comparison.

The IPCC data and the UN reports are all available by searching online. I’m in a meeting at work so right now don’t have the time to dig it out for you, but they’re publically available.

The reforestation is a natural process not any form of government initiative. Do you think that nature just stops..?! Again, google it. Many articles showing secondary and tertiary rainforest regrowth in surprisingly short timescales.

 

[EmilysDad]

that hurts my head Craig .....

 

[Craiglxviii]

that hurts my head Craig .....

It’s one of those simple things that aren’t simple. Move it into water and it gets weirder; wetted area becomes the primary factor when fully immersed but block coefficient and rate of change of profile are the main factors when only breaking the surface, which is why ships are long and narrow with pointy ends, but submarines are short and fat with a rounded nose.