Motorway 60mph Air Quality Trial

Zep

Administrator
Messages
4,577
In Newport on the M4 there is an area where it goes down to 50 because the signs say kill speed air pollution kills.....Now, I don't know a lot about this stuff but surely if you are doing 70 you get through this area quicker so less pollution.....Or if you go 50 you are in the area for longer so more pollution. Now if there is more pollution at 70 then surely the fact you are in the area for longer at 50 it cancels it all out and 70 is no different to 50 ?
A common misconception. Friction losses from airflow cube with any increase in velocity. So as an example if you reduce velocity by 20% friction from airflow reduces by 50% and therefore energy needed to overcome it reduces by 50%. So despite being in the area for longer, the amount of fuel and therefore emissions are reduced.

Put it this way, if the fuel light is on in your car and you are worried you won’t make it to the petrol station, do you drive there more quickly, or more slowly?
 

safrane

Member
Messages
13,492
The Newport one is daft as you brake, producing brake pad dust and rubber pollution off the tyres, only to accelerate hard at each end as you climb the hill producing far more emissions than you would have if you stayed at a constant speed... its only 1/2 a mile too.
 

RobinL

Member
Messages
350
We have a few in N Wales..in fact had them a while. The A494 by Queensferry works ok to be honest. Cruise control on for an indicated 55.(2mph error, plus 2 mph allowance plus 20% of the accepted 10% margin of error!) It does slow things down but for a short 5 miles it's ok.
My worry is that local councils, Govmnt, don't usually stop there.
Next it will be miles of restrictions.Averaging speed cameras make it too easy.

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rockits

Member
Messages
7,996
I think this is the issue that often councils grab onto the idea and blanket apply these to other areas that don't require the same restrictions. We have seen 20mph limits applied in many inner city areas the same way.

Almost back to the days of speed cameras being installed at site of accident black spots. However many were installed in areas that never had accident blackspots.

I have no issue with improvements being made when they make sense and are required. Just seems much of this is another example of reduced civil liberties.
 

RobinL

Member
Messages
350
As the A494 Averaging cameras straddle the England/Wales border at Queensferry I am curious as to whether they could be 're-purposed' to filter out and record English registered cars?

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allandwf

Centenary Club
Messages
9,047
I can see the electric, and nice to try feelgood green options, taking a back seat once the full effect of covid kicks in. People on minimum wage or no wage at all, and they won't be interested. Hopefully I'm wrong.
 

sionie1

Member
Messages
681
Stop building massive housing estates by motorways and plant some more trees.... if I could be bothered I’d find the link to a tv programme a couple of years ago in which the researchers placed trees on a London road and measured the pollution before and during in the houses. I think ash trees won the day with some significant reduction Vs the houses with nothing.
 

rockits

Member
Messages
7,996
I saw that too. Massive reduction in polution in the homes close to a major road just because they planted a row of trees between the road Infront of the houses. The trees became the filter and absorber of a decent percentage of those emissions.
 

Felonious Crud

Centenary Club
Messages
15,301
Stop building massive housing estates by motorways and plant some more trees.... if I could be bothered I’d find the link to a tv programme a couple of years ago in which the researchers placed trees on a London road and measured the pollution before and during in the houses. I think ash trees won the day with some significant reduction Vs the houses with nothing.
I saw that too. Massive reduction in polution in the homes close to a major road just because they planted a row of trees between the road Infront of the houses. The trees became the filter and absorber of a decent percentage of those emissions.
I seem to remember that conifers won the day. It was an insightful programme, that.
 

Alan Surrey

Junior Member
Messages
82
The plane trees in London are known to do a great job. In Victorian times they were the only tree that could survive the coalsmoke and thrive.
 

BennyD

Sea Urchin Pate
Messages
13,955
Best we file this under ill thought-out knee-jerk bolloxcs along with ‘smart’ motorways and bus lanes. HGVs should only be allowed in the left two lanes however many lanes a motorway has; 3 heavies ‘Elephant racing’ for miles turns a smart motorway into a dual carriage way which doesn’t help congestion.