20mph Wales

user1977

force_ten1 said:

wee jimmy crankie and the snp cronies did in the Scottish Borders

How would they have done that, given the SNP has never run Borders Council?

ontheroad1970

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.

National speed limit is still 60 on single carriageway 70 on double.  Do read  more

ontheroad1970

MouldyOldDough said:

born_again 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 

Does not compute
Unless you are a idiot & sit in 1st gear. Plenty or 20 zones round here on residential streets. Causes no problems & makes it safer for all road users.

Yes it does - if your car doesn't like top gear at 20mph (and I don't know what car does) - and remains in a lower gear - the engine will be turning at faster revs - than it would in top gear - so the exhaust  will be pumping out more noxious gases (per mile) !

Simple

I am not denying the safety side of it !!!!

You don't have to use top gear though

HHarry

MouldyOldDough said:

born_again 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 

Does not compute
Unless you are a idiot & sit in 1st gear. Plenty or 20 zones round here on residential streets. Causes no problems & makes it safer for all road users.

Yes it does - if your car doesn't like top gear at 20mph (and I don't know what car does) - and remains in a lower gear - the engine will be turning at faster revs - than it would in top gear - so the exhaust  will be pumping out more noxious gases (per mile) !

Simple

I am not denying the safety side of it !!!!

You may have to use a lower gear, but you are travelling at a slower speed, so the rpm isn’t necessarily more than 30mph in top.

victor2

HHarry said:

MouldyOldDough said:

born_again 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 

Does not compute
Unless you are a idiot & sit in 1st gear. Plenty or 20 zones round here on residential streets. Causes no problems & makes it safer for all road users.

Yes it does - if your car doesn't like top gear at 20mph (and I don't know what car does) - and remains in a lower gear - the engine will be turning at faster revs - than it would in top gear - so the exhaust  will be pumping out more noxious gases (per mile) !

Simple

I am not denying the safety side of it !!!!

You may have to use a lower gear, but you are travelling at a slower speed, so the rpm isn’t necessarily more than 30mph in top.

But you're covering less distance for the same fuel used at 20mph...

HHarry

victor2 said:

HHarry said:

MouldyOldDough said:

born_again 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 

Does not compute
Unless you are a idiot & sit in 1st gear. Plenty or 20 zones round here on residential streets. Causes no problems & makes it safer for all road users.

Yes it does - if your car doesn't like top gear at 20mph (and I don't know what car does) - and remains in a lower gear - the engine will be turning at faster revs - than it would in top gear - so the exhaust  will be pumping out more noxious gases (per mile) !

Simple

I am not denying the safety side of it !!!!

You may have to use a lower gear, but you are travelling at a slower speed, so the rpm isn’t necessarily more than 30mph in top.

But you're covering less distance for the same fuel used at 20mph...

 But the air resistance is less, so it takes less energy to move through it.  It’s a complicated issue!

 There were a number of justifications for dropping the limit to 20mph, some of which I have greater issues with than fuel economy.

 “It will encourage people to use public transport and bicycles” -  Possibly if you live in Cardiff or Swansea, but a fair chunk of Wales is rural communities with poor or non-existant public transport.  And I don’t fancy cycling along an unlit NSL country lane.

 “It will improve air quality” - again, quite possibly in the cities but I’d suspect that any improvement in my local town would be so small it would be unmeasurable.

 It’s a policy that is flawed for many reasons.

MouldyOldDough

HHarry said:

MouldyOldDough said:

born_again 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 

Does not compute
Unless you are a idiot & sit in 1st gear. Plenty or 20 zones round here on residential streets. Causes no problems & makes it safer for all road users.

Yes it does - if your car doesn't like top gear at 20mph (and I don't know what car does) - and remains in a lower gear - the engine will be turning at faster revs - than it would in top gear - so the exhaust  will be pumping out more noxious gases (per mile) !

Simple

I am not denying the safety side of it !!!!

You may have to use a lower gear, but you are travelling at a slower speed, so the rpm isn’t necessarily more than 30mph in top.

HHarry said:

MouldyOldDough said:

born_again 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 

Does not compute
Unless you are a idiot & sit in 1st gear. Plenty or 20 zones round here on residential streets. Causes no problems & makes it safer for all road users.

Yes it does - if your car doesn't like top gear at 20mph (and I don't know what car does) - and remains in a lower gear - the engine will be turning at faster revs - than it would in top gear - so the exhaust  will be pumping out more noxious gases (per mile) !

Simple

I am not denying the safety side of it !!!!

You may have to use a lower gear, but you are travelling at a slower speed, so the rpm isn’t necessarily more than 30mph in top.

Slower speed = less distance per g of noxious gas
To get from a to b will take longer so more gas emissions 

CliveOfIndia

MouldyOldDough said:

HHarry said:

MouldyOldDough said:

born_again 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 

Does not compute
Unless you are a idiot & sit in 1st gear. Plenty or 20 zones round here on residential streets. Causes no problems & makes it safer for all road users.

Yes it does - if your car doesn't like top gear at 20mph (and I don't know what car does) - and remains in a lower gear - the engine will be turning at faster revs - than it would in top gear - so the exhaust  will be pumping out more noxious gases (per mile) !

Simple

I am not denying the safety side of it !!!!

You may have to use a lower gear, but you are travelling at a slower speed, so the rpm isn’t necessarily more than 30mph in top.

HHarry said:

MouldyOldDough said:

born_again 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 

Does not compute
Unless you are a idiot & sit in 1st gear. Plenty or 20 zones round here on residential streets. Causes no problems & makes it safer for all road users.

Yes it does - if your car doesn't like top gear at 20mph (and I don't know what car does) - and remains in a lower gear - the engine will be turning at faster revs - than it would in top gear - so the exhaust  will be pumping out more noxious gases (per mile) !

Simple

I am not denying the safety side of it !!!!

You may have to use a lower gear, but you are travelling at a slower speed, so the rpm isn’t necessarily more than 30mph in top.

Slower speed = less distance per g of noxious gas
To get from a to b will take longer so more gas emissions 

Unfortunately it's not quite that simple.  Every car/engine combination will have a "sweet spot" where it's most efficient.  Yes, on the face of it, going slowly burns less fuel but for a longer period of time.  Going quickly burns more fuel but for a shorter period of time (to cover the same distance).

Back when I was a kid, the speed of 56mph was always quoted as the "benchmark" speed for fuel economy comparisons - and even that was a rough average based on the majority of "average" cars.  But every car is different - and its most efficient "burn-rate", for want of a better word, will differ depending on the road, traffic, weather conditions.  Cruising along a level, traffic-free motorway at 70mph - the highest gear will give you best economy, since the engine is turning at the lowest possible RPM for the speed (and you don't need much power or torque to maintain a steady speed on a level road).  But going up a hill, you may be able to do it in top gear, but you may be needing to keep your right foot buried in the carpet.  It can often be more fuel-efficient to change down a gear or two - even though the engine RPM is then greater, the overall fuel economy is improved.

And at the end of the day, fuel economy near-as-dammit is a direct correlation to emissions.  There is no one-size-fits-all "ideal speed", in terms of fuel economy - it depends on a whole host of inter-dependent factors.

Herzlos

MouldyOldDough said:

HHarry said:

MouldyOldDough said:

born_again 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 

Does not compute
Unless you are a idiot & sit in 1st gear. Plenty or 20 zones round here on residential streets. Causes no problems & makes it safer for all road users.

Yes it does - if your car doesn't like top gear at 20mph (and I don't know what car does) - and remains in a lower gear - the engine will be turning at faster revs - than it would in top gear - so the exhaust  will be pumping out more noxious gases (per mile) !

Simple

I am not denying the safety side of it !!!!

You may have to use a lower gear, but you are travelling at a slower speed, so the rpm isn’t necessarily more than 30mph in top.

HHarry said:

MouldyOldDough said:

born_again 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 

Does not compute
Unless you are a idiot & sit in 1st gear. Plenty or 20 zones round here on residential streets. Causes no problems & makes it safer for all road users.

Yes it does - if your car doesn't like top gear at 20mph (and I don't know what car does) - and remains in a lower gear - the engine will be turning at faster revs - than it would in top gear - so the exhaust  will be pumping out more noxious gases (per mile) !

Simple

I am not denying the safety side of it !!!!

You may have to use a lower gear, but you are travelling at a slower speed, so the rpm isn’t necessarily more than 30mph in top.

Slower speed = less distance per g of noxious gas
To get from a to b will take longer so more gas emissions 

Only if engine speed is directly related to fuel consumption like in an old carburetor engine. With modern computer controlled injection. Slower speed will mean less fuel used per distance unless you're thrashing it i.e. 20mph in 1st.

Martyn1981

Herzlos said:

MouldyOldDough said:

HHarry said:

MouldyOldDough said:

born_again 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 

Does not compute
Unless you are a idiot & sit in 1st gear. Plenty or 20 zones round here on residential streets. Causes no problems & makes it safer for all road users.

Yes it does - if your car doesn't like top gear at 20mph (and I don't know what car does) - and remains in a lower gear - the engine will be turning at faster revs - than it would in top gear - so the exhaust  will be pumping out more noxious gases (per mile) !

Simple

I am not denying the safety side of it !!!!

You may have to use a lower gear, but you are travelling at a slower speed, so the rpm isn’t necessarily more than 30mph in top.

HHarry said:

MouldyOldDough said:

born_again 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 

Does not compute
Unless you are a idiot & sit in 1st gear. Plenty or 20 zones round here on residential streets. Causes no problems & makes it safer for all road users.

Yes it does - if your car doesn't like top gear at 20mph (and I don't know what car does) - and remains in a lower gear - the engine will be turning at faster revs - than it would in top gear - so the exhaust  will be pumping out more noxious gases (per mile) !

Simple

I am not denying the safety side of it !!!!

You may have to use a lower gear, but you are travelling at a slower speed, so the rpm isn’t necessarily more than 30mph in top.

Slower speed = less distance per g of noxious gas
To get from a to b will take longer so more gas emissions 

Only if engine speed is directly related to fuel consumption like in an old carburetor engine. With modern computer controlled injection. Slower speed will mean less fuel used per distance unless you're thrashing it i.e. 20mph in 1st.

Plus, there seems to be an assumption of constant speed. But in city driving, especially these 20mph roads in Cardiff, there will be a lot of 'opportunities' to slow down, such as junctions, traffic lights, and pedestrian crossings. If the vehicle is travelling at 30mph (rather than 20mph) and needs to stop, then it has to lose 2.25x as much kinetic energy, energy that was built up by burning fuel with the associated emissions.