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I’d be curious to see the reduction in tire and brake particulate from lower speeds, it’s not only exhaust that is bad. EVs are a lesser evil but they don’t just emit candy floss. Noise is a factor too.
Tyre emissions are roughly proportional to g-forces exerted by the wheels, so at a steady speed, on a motorway, without stop/start driving it's likely they are pretty low on both ICE and BEV. As we know most BEV tend to be heavier, so the baseline emission is probably slightly higher there but I doubt it's noticeable.

Brake emissions of course are on average lower on BEV because of regen braking - though the cars are heavier too .. so you win some you lose some.

There are a few studies that show that tyre particulates are generally much larger than particulates from ICE engines, so are much less likely to be harmful, and occur at much lower rates than exhaust emissions too. They tend to fall to the ground and are effectively filtered by the body's natural defenses. Unlike the mass of PM2.5 that comes out of a diesel.

I would not be surprised to find that reducing the average speed by 10mph makes a pleasant improvement on the quality of noise even if not particularly the level of it. I'm sure the neighbours would like it..
 

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And yet our average speeds are the same as most of europe. Only the few, short stretches of "unrestricted" autobahn tend to sustain higher average speeds than UK motorways outside rush hour. (Excluding the city motorways like the M25 of course .. )
 

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Reference?
I'm gonna say.. I can't find it now. :) I found some references that suggest maybe I'm out of date, and UK roads are now too congested for anyone to really ever find "free running" motorway, but I don't completely believe that.
It was pretty common knowledge that the police never bothered stopping people doing less than about 80 on motorways, but advice was that foreign roads are more tightly enforced. I think cameras have played a part in generally bringing speeds down in the UK, a little. But traffic levels have done more..
 

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I'm gonna say.. I can't find it now. :) I found some references that suggest maybe I'm out of date, and UK roads are now too congested for anyone to really ever find "free running" motorway, but I don't completely believe that.
It was pretty common knowledge that the police never bothered stopping people doing less than about 80 on motorways, but advice was that foreign roads are more tightly enforced. I think cameras have played a part in generally bringing speeds down in the UK, a little. But traffic levels have done more..
Living in South Wales I'm often on the M4, it's free running much of the time. Yes, there are large 50 mph sections at Port Talbot and Newport.

I often used to drive South Wales to Bedfordshire. I didn't have issues "doing the speed limit".
 

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Discussion Starter · #28 ·
I've read the various replies here and I still don't see a valid reason for "safety"
There are lots of vehicles at different speeds the whole time, across the whole country.

I am expected to check mirrors and make a safety based decision when thinking to change lanes
This is fully to involve interpretation of the approach speed of any vehicle in a lane I wish to move to.
It ain't rocket science.
Every day this involves people going faster or MUCH FASTER than I, including when I am doing 70.01mph

Likewise if I am in 50mph roadworks average speed zone before I change lane I need to check if Sammy Sales is thundering down on me at 65 whose sales commission will easily pay the speeding fine

I do take the point that the large % of EV drivers are more likely to be doing 60 rather than 70.

But the overall point is why should/would EVs be speed limited " to reduce engine emissions " - when they don't make them
(Note I put engine in there, to push off the tyres brake dust etc)
 

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I've read the various replies here and I still don't see a valid reason for "safety"
There are lots of vehicles at different speeds the whole time, across the whole country.

I am expected to check mirrors and make a safety based decision when thinking to change lanes
This is fully to involve interpretation of the approach speed of any vehicle in a lane I wish to move to.
It ain't rocket science.
But people are human and make mistakes. Having cars overtaking at higher than expected speeds will inevitably create accidents. And I KNOW that people speed, and as a result there are probably accidents due to people pulling out in front of such cars, it's just that statistically if speed differences are more common then such accidents will be more common. It's just plain common sense (and statistics).
I'm the first to complain about unnecessary and illogical restrictions when driving (don't get me started on chicanes) but in this case I can see the argument. Actually, I will get started on chicanes ! All they do is cause me to speed up so I can get through before the oncoming traffic starts hooting at me.
 

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Discussion Starter · #34 ·
Yeah but I wanted differing opinions - s'only by asking and listening to replies I challenge my own view to see if I should get off the soapbox with a smile of agreements around me, or, shuffle away having learnt something
It's what I read this forum for --- good ideas, bad ideas, and views to challenge my own
 
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But it won't be be unexpected as the rules would be that certain vehicles can do 70 rather than 60.

Just as we have today on motorways.
But we don't have that today. We have vehicles that have to go slower than us, not that can go faster. And also the vehicles that have to go slower are visually obvious (they are bigger).
I feel I'm just stating the obvious. It's a very small increased risk but multiply that by tens of millions of occurrences and statistically there will be accidents. We might choose to say we'll live with a few accidents for the benefit of the EV community, but I'm not sure that's how the powers that be see it.
 

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This thread is starting to resemble one of those crazy "what if?" threads on Quora where someone asks how Quickly Germany would've won WW2 if they had access to 1980s planes and tanks.
I agree, we'll never know as it's never going to happen.

@doctony - you're looking at it purely from a light vehicle perspective in saying that "we don't have that today".
Lorries, vans, caravans have to deal with it... (well they should legally have to).
 

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I agree, we'll never know as it's never going to happen.

@doctony - you're looking at it purely from a light vehicle perspective in saying that "we don't have that today".
Lorries, vans, caravans have to deal with it... (well they should legally have to).
Of course I am, because that's what the discussion is about. A commercial vehicle looking in his rear view mirror knows that a car (which is easily distinguishable from other commercial vehicles) is very likely to be travelling at higher than his speed. That would not be true for cars, as there would be two sorts of cars. And I know it's all down to good lookout and anticipation but I'm afraid there are a lot of drivers who seem incapable at a glance of assessing a closing speed. And also, we all make mistakes - and the statistical likelihood of "getting away" with a mistake is better if there's less mismatch of speed. The problem with speeding for example is not that it is intrinsically unsafe, but that someone will do something unexpected in front of you.
 

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Duh ... let me google that for you.


View attachment 165566

Not only is it common sense, but it's observed in the real world..
Duh! What?

How does that show it is 'proportional' to?

I accelerate like glacier and brake so slightly that my discs have rusted up. My tyres still wear out and it is definitely not 'proportional' to the g forces I subject the tyres to.

Each time the rolling patch of a tyre contacts the road, it is compressed, and by this compression the asperities of the rubber grip the road surface. It is MAINLY this constant compression and gripping of the tyre in a straight line at constant speed that causes tyre wear.

For sure if you then add heavy accelerations on top of that it causes more wear, but how much?

Certainly wear is not proportional to G because if that were true then steady speed and straight roads you are stating causes ZERO wear, and I call that out as BS. It's obvious that steady straight line driving does not cause ZERO tyre wear.
 
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