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Apparently all 30mph roads in Wales will drop to 20 next year. Seems a pretty poor idea to me. Im happy for more residential roads to be 20 but there are plenty of 30 roads are main through routes. I personally think it's disproportionate, unenforceable and will help to further normalise speeding amongst many drivers.
I get the safety aspect but if people don't stick to them it won't work.
It's been 20mph in London for a while now. Guess what, it's fine
Read that the other day, sounds like a bit of a daft idea without proper reasoning, planning and policing.
Edinburgh is 20moh most places now. It works and if introduced properly traffic flows actually speed up.
It also vastly better for cyclists and pedestrian
Apparently all 30mph roads in Wales will drop to 20 next year. Seems a pretty poor idea to me. Im happy for more residential roads to be 20 but there are plenty of 30 roads are main through routes. I personally think it’s disproportionate, unenforceable and will help to further normalise speeding amongst many drivers.
I get the safety aspect but if people don’t stick to them it won’t work.
Its been 20 in all built up areas in the Scottish Borders for about 3 years now. ITs fantastic. do people stills speed? yes ofcourse but i'd wager the average speed is way down. These things are about averages.
Its such a non issue
It also vastly better for cyclists and pedestrian
Yep including the pedestrian on the pavement, things are calmer things feel safer on narrower pavement etc.
I'm all for it, hope they do it in England (fat chance - can you imagine the uproar?!?).
Had it in Brussels for a year and a half now. It's fantastic as a cyclist and even as a driver it's a little annoying initially but that's mainly because everyone drives up your bum and now that it has all calmed down its way calmer in the car too
Presumably they can still actively choose to make some roads a 30 much like some roads are 40s but I think it makes sense as a default
Plenty of towns etc in Wales already are, very noticeable when I go biking or on holiday there! Sounds like a good idea to me, even if the effect is just that the speeders do 25 or 30 rather than 35-40! (though I hope they're enforced 🤣)
It works and if introduced properly traffic flows actually speed up.
Indeed - what dictates the time it takes to travel through an urban area isn't the maximum speed you can reach but the amount of time you spend stationary at junctions. The faster traffic is travelling the fewer opportunities you have to pull out from a junction or at roundabouts or to turn across traffic. Where theres traffic lights the amount of tine they're red does't change so 20 or 30mph is just the peak speed you reach between being stationary but the overall travel time is the same. Slower top speeds for traffic means less time stationary during a journey.
There are all sorts of benefits for all road users if cars driving at 20, zero benefits for drivers if they drive at 30 - other than the comfort of it being what they're used to if you hate change.
I reckon in towns and residential areas "20 is plenty", but yes there are probably lots of 30mph roads which can safely be left at that speed. I understand there is leeway for this to happen in the Welsh proposals.
It's great. We've had it in Bristol for a few years now. Better as a driver and much better as a cyclist and pedestrian. Not much to complain about (but lots do)
It's about time we had them here, love the ones in Bristol.
ITs fantastic. do people stills speed? yes ofcourse but i’d wager the average speed is way down. These things are about averages.
That's the thinking: a speeder in a 30 is doing 35, a speeder in a 20 is doing 25. It also makes things a lot calmer on the roads as the speed differential between cars, lorries, bikes and those electric scooters is much less. It also has the added effect of subconsciously forcing people who want to make progress to use the trunk roads rather than the rat runs.
Presumably they can still actively choose to make some roads a 30 much like some roads are 40s but I think it makes sense as a default.
That's how it's planned to work in reality. They've already done most of Cardiff and the main arterial routes are signed as 30/40/50 depending on the road. Works really well.
I live in Bristol too, it's fine - barely notice it tbh. Half the time the traffic is too heavy to go over 10mph anyway. The rest of the time it means you take slightly longer to get to the next red light, and spend slightly less time waiting there as a result
It’s been 20mph in London for a while now. Guess what, it’s fine
It's not blanket 20mph though is it, plenty of roads are still 30mph, which is actually worse as its easy to loose track of what the speed limit actually is, especially with everything else going on when driving around London.
Excellent news. Scotland due to follow in 3 years IIRC.
I’m in and out of Edinburgh most days, at different times.
Haven’t really noticed much difference tbh, ‘maybe’ it’s a little more relaxed.
It’s made absolutely no difference to my journey times though.
And i do pay attention to that, because i drive a coach.
There was a fair bit of rhetoric before it, about how it would cause chaos, but it really makes no difference at all that i can see.
Apparently all 30mph roads in Wales will drop to 20 next year.
NO
The default speed limit will be 20 i.e. where there are no signs. Councils can still create 30mph speed limits wherever they want.
The idea is that 30s will exist on through roads and things like residential side streets will be 20 without them having to put up millions of signs.
WHat they are planning is all restricted roads go to 20, a traffic order will be needed to bump them up to 30, it's the other way around at the moment.
I do think 20 limits have their place and should be extended but we don't all live in big, densely congested urban population centres, there's lots of 30 zones in rural areas as well, often the main route through a village. For example the road from Rochdale to Burnley is mainly 30, probably 9 miles out of the 12, dropping it to 20 would add a significant amount of time and get largely ignored. I just don't like the idea of having rules that are generally ignored, devalues the rules and normalises rule breaking.
If they were intending to rigorously enforce I'd be OK with it, but they won't. The bit of said road above through our village is approx. 2 miles long and a heavily used commuter route, would be easy to add an average speed camera at each which would stamp out most of the speeding (which is significant) but there's zero will to enforce. Maybe enforce what's already there before going further?
Edit @Molgrips if that's the case I'd be OK with that approach but I think they will have to actively seek a traffic order and then add the appropriate signage, can't see that happening everywhere it needs to.
Nothing must get in the way of the great god car?
How about the folk that live in those villages? Do tjey not have a right to increased safety and reduced pollution?
Dropping speed limits to 20 usually increases traffic flow and average speeds because you dontbget the bunching effect. Every been on a busy motorway and traffic cones to a halt but when it clears there is no obstuction? Thats the bunching / concertina effect and reduced speed limits eliminates that. It happens in busy 30 mph limits as well but is less obvious.
I just don’t like the idea of having rules that are generally ignored, devalues the rules and normalises rule breaking.
Which is already the case with most speed limits. As already said, reducing it by 10mph might not mean that everyone obeys the 20mph limit but it will slow (almost) everyone down to less than 30mph. This can already be seen in places where speed limits have been reduced.
FWIW from what I read, the limit will be reduced in "built up areas". Your example might not qualify anyway.
Fro my experience in Edinburgh the 20 mph limit has pretty much been ignored. In fact I’ve just read an abstract of a survey which suggests an average speed reduction of 1.34 mph. Not sure that would be discernible to the naked eye.
EDIT https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0261383
The average speed isn't the maximum speed though. The limit might well have been 30 before but the average speed would have been much less due to congestion etc. Reducing the maximum by 10 doesn't mean reducing the average by 10.
When it's busy it only takes one person to obey the limit, then everyone else has to as well.
Fro my experience in Edinburgh the 20 mph limit has pretty much been ignored. In fact I’ve just read an abstract of a survey which suggests an average speed reduction of 1.34 mph.
Hang on. That may not be because everyone's breaking the limit. I would not expect average speeds to go down much when limits are dropped to 20 because as most road cyclists know your average speed is dominated by stoppages which will still be there.
Also, according to that study, arterial routes remained at 30 and 40.
Interesting. My impression is that its made a significant difference and thst its a lot nicer and safer to cycle in the city. Idiots have not slowed but most folk have and car drivers are more willing to sit behind you
As above Scottish borders is 20 but some longer approaches into town been bumped back to 30. There are led warning signs, "your speed is" signs and normal small lamppost repeaters. It now feels to fast when I get to langholm and it's 30.
I’ve just read an abstract of a survey which suggests an average speed reduction of 1.34 mph
Thanks for the link. It's interesting - obviously that speed decrease is not equal across the board. In some areas, ave speed was barely over 20mph to begin with, so speeds there didn't decrease much.
Interesting to note that faster drivers seemed to slow down by more - drivers clocked at over 24mph slowed by over 2mph, which is getting on for 10% - not too bad IMO
It’s made absolutely no difference to my journey times though.
Thats the point that the hand wringers miss. in a city/congested town its less noticable as you never hit 30 anyway. what it does is smooths the journey though. Less stop start. less braking and accelerating, less idling = less pollution and the lowere peak speed brings down the risks.
In peebles where you CAN get to 30 quite easily (on streets with intermittent parking on both sides and not quite enough width) it brings down the speed noticably. It probably does take longer to get somewhere but the bigger average reduction increases the safety.
The biggest sufferers are those who can't wrap their head around how little difference it makes overall or are perpetually late.
I didnt notice any increase in Edinburgh travel times at all.
Its not blanket either, there are some key routes, which where safe arent 20. And when there are key routes at 20, they are already busy enough that congestion means it doesn't make a difference to overall travel times, it just theoretically inhibits sprints between one bit of congestion and another.
If your curious as to how the range of speed limits is actually applied theres a map here https://cityofedinburgh.maps.arcgis.com/apps/webappviewer/index.html?id=556714cbde034313b0efd04b7fde1700
Presumably they can still actively choose to make some roads a 30 much like some roads are 40s but I think it makes sense as a default
I deed but councils begin councils this will not happen without a massively long process even on some big long road round the side of an industrial estate that has zero business entence.
I think 20 should be the default for all residential streets and area shops but the blanket arpoach mean there are too many area where people think "this is pointless". When I drive I. France I notice a lot more small areas of different speed limits, going into a village will have 70,50,40 and 30kph with only in the real center. Slowing people down gently rather than. 20mph sign that will now start a long way outside the village let alone the center.
Having mixed 20/30 where the mix changes has been a bit of a dog's dinner in Cardiff. We had cowboy neighbourhood 20 signs going up (well I assume that was what they were, they were not to the official design) on roads where the locals were peeved they weren't 20, then they got made 20 but the official signage was all over the place (literally, too many signs, some of them the big ones that ought to mean you are entering a 20 zone whereas in fact you already were in one etc.) Might as well go the whole hog in my view.
All the villages in Perthshire are now 20. There's no congestion on the roads I drive so I am doing 10mph less for about 2 miles of my 11 mile commute.
It's great, the time difference is negligible but there are noticeably more kids on bikes in these areas now
Just flick the speed limiter on the car to 20 and cruise along. No negatives at all despite what the gammon predicted.
It’s a great idea and should be more widespread for all the reasons mentioned so far. Also cuts down on the chances of being killed by a car as opposed to injured should you get hit by one. I’m failing to see any downsides to it.
Great idea bring it on asap, also a blanket speed limit reduction on single lane country roads too please.
Great idea bring it on asap, also a blanket speed limit reduction on single lane country roads too please.
Oooft I can picture the red apoplectic faces already
Our area has been a 20 limit for a few years and it's fine. Any delay I might suffer has nothing to do with the peak speed I can hit, and more to do with congestion at junctions or traffic lights.
Plus the bellends can still boot it like they did before and seldom get caught, there's a couple of cameras which are apparently still set to 30 and very little other enforcement.
Bristol here, big supporter as a cyclist and driver. Legitimises me pootling along in the car.
How about the folk that live in those villages? Do tjey not have a right to increased safety and reduced pollution?
And yet the drivers speed checks catch are commonly locals on short journeys!
Good! I hope we take carry this on in good old England!
The Guardian article on the subject says this:
Currently, just 2.5% of Welsh roads have a speed limit of 20mph, but from next year this is expected to increase to approximately 35%.
So up to 35%. That still leaves plenty more roads at higher limits.
The biggest sufferers are those who can’t wrap their head around how little difference it makes overall or are perpetually late.
When I lived outside Edinburgh the local FB page went into meltdown when the A8 past the airport had it's remaining, short stretch of 70mph reduced to 40mph. There were all sorts of dire predictions about congestion, commuting times, emergency services etc. etc. etc.
Needless to say, when I pointed out that the actual difference to journey times would be about 12 seconds, I was roundly ignored, actual maths and facts just did not cut through the red mist obviously! 😂
Although... even I had to admit on my rare motorised commute home that I missed the opportunity to floor it and boot along at 70 for a few precious seconds after crawling through the city 🙄
I just don’t like the idea of having rules that are generally ignored, devalues the rules and normalises rule breaking.
If they were intending to rigorously enforce I’d be OK with it, but they won’t
I get the safety aspect but if people don’t stick to them it won’t work.
Sounds like you should be arguing for more enforcement rather than not doing it?
I wish we had a government willing to actually show some leadership and start planning for enforced geofencing as we roll into the future. It would be entirely doable, just needs a bit of investment, some legislating and the balls to actually do it. Benefits for safety and environment would be totally worth it.
I see a lot of STWers saying "oh I live in X city, it's fine" please bear in mind, we're not talking about a busy city or town centre, we're talking about a whole Country (I'm not here to debate Wales is or isn't a Country).
When the plan was first announced, I think most people heard "Residential Streets" and thought, yes of course, asking drivers to stick to 20 past homes, schools and shops is perfectly reasonably, and frankly most of the time, certainly where I live in Cardiff, you'll be lucky to travel at half that.
The issues I have with it:
It's completely arbitray, it applies to every 30 mph road, and in the last 3-5 years there's been a huge push from Welsh Gov and Local Councils to reduce previously 40 and 50 mph roads to 30 without justification, no accidents, no new houses etc, just a lot of road paint and signage.
They won't justify it, there have been trials running for years, not only about 20mph roads, but making a lot of dual carriageways and motorways 50. Reports have been promised, and delayed, and delayed and delayed. They introduced a 50mph limited on the M4 at Port Talbot around 2016 promising it would reduce Air Pollution which was high there. I'd doubt you'd need to be a genius to look at the huge heavy industrial complex with its huge chimneys just to the south to work out why, but despite promises, they've never published the report on its effectiveness.
The motivation seems political more than practical, "yay, we beat Scotland".
How about the folk that live in those villages? Do tjey not have a right to increased safety and reduced pollution?
cars are more ecoonomical and less polluting at 30 than at 20. So it would seem they're losing that right.
Reduced speed limits also reduce fuel consumption and so are better for everyone (especially with the cost of fuel being what it is).
However I can also appreciate that some measures are more appropriate for urban areas and that rural workers and businesses could be heavily impacted by increased journey times.
cars are more ecoonomical and less polluting at 30 than at 20. So it would seem they’re losing that right.
I think that's debatable, when you consider that there might be fewer stoppages at 20mph. But cars are certainly quieter at 20mph and less unpleasant to share spaces with.
It’s completely arbitray, it applies to every 30 mph road
That's not what I've read - it applies to residential streets where the streetlights are less than 200 metres apart.
The motivation seems political more than practical, “yay, we beat Scotland”.
I often go to the last post in a thread and scroll backwards, which means I read posts backwards before seeing who posted it. I read that and I knew it was your post 🙂
However I can also appreciate that some measures are more appropriate for urban areas and that rural workers and businesses could be heavily impacted by increased journey times.
As above it's targeted at urban areas, and the idea is not to slow journey times by preserving higher speed limits where it's appropriate. It's not ALL speed limits that are changing - it's only the DEFAULT limit where there are no signs in towns and cities.
leaving local authorities to engage with communities to decide which roads should remain at 30mph.
the time difference is negligible
Yes, at these speeds we can safely ignore relativistic effects.
No negatives at all despite what the gammon predicted
Are you coining a new collective noun here? I like it!
That’s not what I’ve read – it applies to residential streets where the streetlights are less than 200 metres apart.
Those are the roads where 30mph is the current UK-wide default legal speed limit, ie local authorities do not need to pass by-laws to set 30 as the speed limit but they would to make it 20 or 40. They still put up signs though. I assume the proposal is to change that default to 20 in Wales.
guidance for motorists:
https://www.gov.uk/speed-limits
and guidance for local authorities:
https://www.gov.uk/government/publications/setting-local-speed-limits/setting-local-speed-limits
I assume the latter is still valid as it is on the .gov.uk, probably if you looked up the legislation referred to you would find the 200m bit.
As above it’s targeted at urban areas, and the idea is not to slow journey times by preserving higher speed limits where it’s appropriate. It’s not ALL speed limits that are changing – it’s only the DEFAULT limit where there are no signs in towns and cities.
Yeah, that much was obvious from my brief perusal of the BBC website, which is why I'd already pointed it out in this thread 😉
I see a lot of STWers saying “oh I live in X city, it’s fine” please bear in mind, we’re not talking about a busy city or town centre, we’re talking about a whole Country.
Nope wrong
Edit, multiple responses already
I see a lot of STWers saying “oh I live in X city, it’s fine” please bear in mind, we’re not talking about a busy city or town centre, we’re talking about a whole Country (I’m not here to debate Wales is or isn’t a Country).
Ah yes, the Scottish borders... the thriving metropolis wall to wall cars and no country villages.
its got a 6th of the population density of wales and is still absolutely fine.
Link to a page linking to the current *Welsh* guidance here - they are updating it.
Basically, local authorities will need evidence-based reasons for going above 20, currently they need that for going below 30. They can't just pass by-laws to maintain the status quo.
less polluting at 30 than at 20. So it would seem they’re losing that right.
Simply untrue. This idea comes from the RAC who did a bit of very slanted fake research and when you dug into it was obvious cherry picking to get the results they wanted
Basic physics tells you it is less energy needed to accelerate to 20 rather than 30
cars are more ecoonomical and less polluting at 30 than at 20. So it would seem they’re losing that right.
Could you show your working out for this please?
Also what about safety are kids in small villages not worth trying to protect?
It’s completely arbitray, it applies to every 30 mph road
To be fair, so's the 30 limit, I presume?
Basic physics tells you it is less energy needed to accelerate to 20 rather than 30
However slightly more advanced physics tells you that it may well be the case that because you might need a lower gear 20mph may be less efficient due to the way the engine is valved, and the fact there'll be more revs of the engine per wheel rev and hence the engine friction plays a bigger part in overall consumption.
I no longer have a car that gives me meaningful on-the-spot fuel economy figures (there is a digital readout on the Merc for it but I think it's the same one from the AMG C63 because it only goes up to 40mpg!) I can't test that theory out.
That "might" is doing some heavy lifting... 😉
The bottom line is, with the speed limit reduced, less people will die. How on earth can you argue against that?
Basic physics tells you it is less energy needed to accelerate to 20 rather than 30
You're forgetting to divide by time taken for the journeys.
Also, most cars efficiency is along a reverse bathtub curve dependent on speed.
That “might” is doing some heavy lifting
It's doing what it needs to do which is to say that it's a bit more complicated than slower = more efficient when it comes to ICE cars.
Feel free to wrap up the debate with some real numbers, I'm quite keen to know. I would be testing this out if I could.
Less speed differential between different urban road users can't be a bad thing, it will be even better when we start using technology to limit speed rather than self administered speeds when not approaching speed cameras. It might well make fossil fuel vehicles a bit less efficient, but I'm presuming it will have no efficiency loss for electric vehicles?
This turned up on a thread on this topic elsewhere (admittedly from a lobby group, but there are citations at the end):
Myth:
A 30 km/h urban speed limit creates more emissionsFact: The opposite is true. Studies have shown that reducing the speed limit from 50 km/h to 30km/h results in a clear reduction in polluting emissions and energy-use. Simply reducing speed results in large reductions in CO2 (about 15%), NOx (about 40%) and carbon monoxide (about 45%). The only exception is hydrocarbons, which rise very slightly (about 4%). Changes to driving style (from aggressive to defensive driving) also makes a big difference. Ideally, drivers would both slow down and change their driving habits, but legislation can only supply the former.
Just to clarify I'm pro 20mph limit and I think it probably won't increase emissions, but I have this knee-jerk reaction whenever someone tries to win an argument with the words 'basic physics'* because physics isn't basic 🙂
* or 'it's a simple fact'. You cannot make something a simple fact just by declaring it so.
The bottom line is, with the speed limit reduced, less people will die. How on earth can you argue against that?
By that logic reduce all speeds limits to 20mph. And because it's a blunt tool so the Welsh government don't have to work out which roads can safely be driven at 30mph.
But there is no logic to these things. Village where I used to live 2 people have been killed in recent years in a 40mph zone (an old lady and young boy). It's still 40mph - it should be 20mph. They won't even put a crossing in.
Yet the wide open A-Road just outside the village has been reduced from national speed limit to 40mph when it can easily cope with 60mph. £1000s spent on new road markings and signage. 🤷♂️
...and then I could turn off the A-road and in theory rag-around on twisty country lanes at 60mph!
I think the variables for the claim that 20mph produces less pollution are too many. You'd have to take into account the infrastructure of each road, how many sets of lights, crossing, road humps, roundabouts, acceleration, braking, junctions, traffic flow, numbers of cars, whether it was on a hill, how steep the hill is, what kind of traffic uses it...I don't think you could make a blanket assumption.
For me, 20mph is all about saving lives and making vulnerable road users more safe. and it certainly does that.
At the risk of adding more "mights", "probably and "Simple facts":
At a constant 30mph i could probably believe that a lot of ICE cars are more efficient at 30mph than at 20mph. But urban driving isn't about driving at a constant speed, its accelerating and braking all the time and accelerating to a higher speed definitely uses more energy than accelerating to a lower one. Its not just exhaust emissions that need to be considered, there is tyre and brake particles and crucially noise too.
Plus the whole dead children thing is fairly important too
Reduced speed limits also reduce fuel consumption and so are better for everyone (especially with the cost of fuel being what it is).
How can that be for an ICE vehicle?
My (automatic) car:
20mph = 1400rpm in 3rd gear
30mph = 1400rpm in 4th gear
..... same rpm/emisions but for 30% longer and higher fuel consumption (less distance travelled for the same consumption).
How can that be for an ICE vehicle?
My (automatic) car:
20mph = 1400rpm in 3rd gear
30mph = 1400rpm in 4th gear….. same rpm/emisions but for 30% longer and higher fuel consumption (less distance travelled for the same consumption).
Get on your bike and do a cadence of 100 in the lowest gear. Then do the same in the highest gear. They are not the same thing at all. Less speed will always require less power. If (and its a big if) a car is less efficient at lower speeds, then that's a design problem, which can be fixed.
You can ignore all of that though and there are still huge safety and quality of life benefits.
There are defitive and quantifiable advantages. What are the actual downsides other than a few minutes lost on journey times? (which is also debatable, as already discussed)
How can that be for an ICE vehicle?
My (automatic) car:
20mph = 1400rpm in 3rd gear
30mph = 1400rpm in 4th gear….. same rpm/emisions but for 30% longer and higher fuel consumption (less distance travelled for the same consumption).
But fuel consumption and emissions are not the same as they do not directly scale to engine RPM. It takes less energy to maintain speed at 20 than it does at 30, so the engine is not working as hard, therefore not using as much fuel.
Many surveys have proved that a lower speed limit does not scale directly to an increase in journy time too - particularly in urban areas. On a road with no junctions or other reasons to stop then yes, journey time will increase. But even then other factors come into play - for example... slowing down from whatever the speed limit is before to 20 means a longer period where the economically minded driver is not using fuel.
It's more complex than your simple sums.
kinetic energy = 1/2 m * V^2 (half mass multiplied by velocity squared)
Now there well may be modifiers due to engine efficiently at different revs, (although you've argued that one out for yourself) but because you are squaring the velocity bit of the equation, that's the dominant factor in the calculation.
1 tonne car at 20mph = 39,605 kg m/s^2 of kinetic engergy
1 tonne car at 30mph = 89,930 kg m/s^2
Which is suppled by the fuel used, so definitely less mpg at higher speeds. Butchers' phyical demonstration, I like that too.
same rpm/emisions but for 30% longer and higher fuel consumption (less distance travelled for the same consumption).
Emissions aren't only related to engine speed. You're doing less work against air resistance at lower speeds, so you need less energy (try riding at 20mph vs 30mph on your bike). In a petrol car that's less of a difference because (unless it's direct injection) you need a certain amount of fuel in the cylinder for ignition. But if you have a TFSI engine or a diesel then it holds true.
And the acceleration point as above. But it's not simple, you probably won't be on the roads for 50% longer or even 30%. A local road that has had a 20 on it recently is about 1km long, but most of your time on it you are queueing at the roundabout at the end. Slowing that roundabout up would actually have a far greater effect on emissions on all the joining streets than the actual speed limit.
If you are genuinely concerned about emissions then drive less. It's a just a load of whataboutery.
Slower streets make them nicer places to be for all users.
If you are genuinely concerned about emissions then drive less.
If I cycle it doesn't affect everyone else's emissions 🙂
It’s doing what it needs to do which is to say that it’s a bit more complicated than slower = more efficient when it comes to ICE cars.
Feel free to wrap up the debate with some real numbers, I’m quite keen to know. I would be testing this out if I could.
But at the basic level, as previously defined, a lower speed requires less energy to reach and maintain, therefore a given road vehicle will use less fuel going slower rather than faster, no?
therefore a given road vehicle will use less fuel going slower rather than faster, no?
Not necessarily because whilst you are doing less work the efficiency of the whole car is lower at that kind of low speed. For various reasons. And whilst dropping from 60mph to 40mph saves a lot of required energy, dropping from 30 to 20 doesn't save as much because as we know air resistance is proportional to the square of speed. That means that inefficiencies in the powertrain can become more significant. But on the other hand, as above, the energy required for acceleration may also dominate depending on the road itself.
From memory, in the Passat that had the instant readout, driving at 30-40mph didn't seem to be much more efficient than 50mph, if at all.
Find the RAC "research " if you want a laugh. They tried to prove 20mph caused greater fuel consumption and emissions but its laughable and was quickly picked apart and they had to admit that in the real world 20mph cut fuel consumption and emmision.
Im sure you guys would love it
Has no one mentioned the BBC article yet?
https://www.bbc.co.uk/news/uk-wales-62020427
angry gammon says....
"Cyclists are having a whale of a time on Liverpool Road because they can do more than 20mph on their bikes and we can't do more than 20mph in a car - so I've had quite a lot of reports of people being overtaken by cycles."
Tried yesterday on a long flat straight in town 20 limit going to a 40.
In 20was a smidge over 1200rpm in 3rd only need to change down if in traffic.
30 needle just touching 1200 in 4th but weirdly need to drop to 3rd if slowing to 25 or on hills.
We've had it for. A couple of years and it is a nice speed for town. Just stick it in cruise control and all's good. We had/have the usual "its too slow" folk but it honestly make no real difference to ETAs and the time you have to leave by the time you take into account lights and traffic and junctions etc.
its got a 6th of the population density of wales and is still absolutely fine
Which bit of Wales?
We have it here in the Scottish Borders and is ace. Yes people go faster but they also broke the 30mph limit so average speeds are lower.
The arguments against it are weak and don't stand up to any sensible challenge. The people who object the most are your Daily Mail comments types. It's safer, quieter, greener and doesn't really take any more time. It encourages active travel and when the roads are busier I'm sure it speeds things up as much easier to pull out of junctions.
People just don't want to be told what to do in their cars. The thing is, roads are jot just for cars.
I have no problem with 20 on residential roads, and I hope it will mean we can get rid of road humps. They are a particular disincentive to use of small cars, as they are disproportionately affected. A 30mph speed limit with obstructions that can't be safely taken at over 15mph is not useful. They're also bad for bikes, and even worse for trikes.