20mph Wales

MouldyOldDough

https://mol.im/a/12393711
I can't see this actually happening.....
It's going to cause more pollution due to low gear 
More noise due to high revs 

The_Unready

Well, the Welsh government can always raise the speed limits again so that more people are killed and maimed. Would you prefer that?

As for pollution, not everyone agrees:

https://www.20splenty.org/pollution.htm

WellKnownSid

MouldyOldDough said:

https://mol.im/a/12393711
I can't see this actually happening.....
It's going to cause more pollution due to low gear 
More noise due to high revs 

I don’t think 20mph is noisier vs 30mph
i doubt pollution is higher - that would make no sense
The death rate amongst small children running out in front of the car will be arguably lower which some will no doubt consider a negative 🙄

MouldyOldDough

WellKnownSid said:

MouldyOldDough said:

https://mol.im/a/12393711
I can't see this actually happening.....
It's going to cause more pollution due to low gear 
More noise due to high revs 

I don’t think 20mph is noisier vs 30mph
i doubt pollution is higher - that would make no sense
The death rate amongst small children running out in front of the car will be arguably lower which some will no doubt consider a negative 🙄

Of course pollution will be higher 
Higher revs = more grams CO2 and N2O per mile
Can your 6 speed car maintain 20mph in 6th gear? 

prowla

Wales is a funny old place - the locals tell people not to go there and then they complain that tourism is struggling.

Now there's a new national speed limit, so things will take longer; I expect there'll be complaints that deliveries are taking too long or cost more.

Brie

If the traffic flow is maintained better at 20mph wouldn't that lessen pollution?  The problem we have around here (not in Wales) is the people that rev up to 40 or 50 mhp in a 30 zone and then have to break suddenly and then rev up again when the road is clearer.  I'd be well happy to have the area as 20 mph if it cut the actual cars down to nearer 30.  

MouldyOldDough

The_Unready said:

Well, the Welsh government can always raise the speed limits again so that more people are killed and maimed. Would you prefer that?

As for pollution, not everyone agrees:

https://www.20splenty.org/pollution.htm

"Choice of gear and driving style, not the number on the speed limit sign, most affect fuel use[3]. DfT guidance states, “Generally, driving more slowly at a steady pace saves fuel and carbon dioxide emissions, unless an unnecessarily low gear is used”. Is vague to say the least

WellKnownSid

MouldyOldDough said:

WellKnownSid said:

MouldyOldDough said:

https://mol.im/a/12393711
I can't see this actually happening.....
It's going to cause more pollution due to low gear 
More noise due to high revs 

I don’t think 20mph is noisier vs 30mph
i doubt pollution is higher - that would make no sense
The death rate amongst small children running out in front of the car will be arguably lower which some will no doubt consider a negative 🙄

Of course pollution will be higher 
Higher revs = more grams CO2 and N2O per mile
Can your 6 speed car maintain 20mph in 6th gear? 

No but my hybrid spends a lot more time in pure EV mode at 20mph

And CO2 being proportional to V^3 will be lower

I appreciate that “the system” is gradually eroding your God-given right to drive a motor vehicle and all that, but hasn’t that always been the case ever since they had that bloke walk in front of a horseless carriage carrying a flag?

forgotmyname

WellKnownSid said:

I don’t think 20mph is noisier vs 30mph
i doubt pollution is higher - that would make no sense
The death rate amongst small children running out in front of the car will be arguably lower which some will no doubt consider a negative 🙄

20mph vs 30mph will depend on the car and the revs. Quite possible that some cars need a lower gear and more revs at 20mph. I cannot do 3rd gear

at 20mph in my car so the revs are increased keeping it in 2nd.  So yes possibly worse pollution.
Never tested 20mph but cannot imaging getting anywhere close to the quoted MPG figures at 20mph.

Overall noise though is variable, extra engine noise but reduced road noise from the tyres?  That will vary even more than the revs/speed with different
brands of tyres.

Limit lowered here because of an accident almost 1 mile away.  The driver unlicenced and uninsured was doing in excess of 60mph
in a 30mph limit close to a school, and people are still doing stupid speeds in the 20mph so no changes there. Additional road safety
= zero because there were zero accidents before that incident.

The pollution results on the website done in 1990/92 where cars engine/power/gearing will have been different.  A 1970's Austin Maxi could do
sub 10mph up hill in 4th gear. Try that with a modern manual car.  And many cars will be different so what may work for one may not work
for others.  For my car 42mph in 4th gear is the most efficient I can get almost 70mpg (2L Diesel).

DE_612183

prowla said:

Wales is a funny old place - the locals tell people not to go there and then they complain that tourism is struggling.

Now there's a new national speed limit, so things will take longer; I expect there'll be complaints that deliveries are taking too long or cost more.

Generalisations are funny old things....

DE_612183

Brie said:

If the traffic flow is maintained better at 20mph wouldn't that lessen pollution?  The problem we have around here (not in Wales) is the people that rev up to 40 or 50 mhp in a 30 zone and then have to break suddenly and then rev up again when the road is clearer.  I'd be well happy to have the area as 20 mph if it cut the actual cars down to nearer 30.  

This is what I've seen - the main road through our village was 30mph, but it's a road that people use to get into Cardiff, they used to come off the duel carriageway and then go past the schools and crossings at 40mph - there were accidents which resulted in the worse cases of fatalities.

Now we have 20mph, and people still speed, but only up to about 25 at most - there are still some idiots but most are slowed down by the rest of the tarffic.

Yes it's quieter.