Motorway 60mph Air Quality Trial

rockits

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7,996
So Highways England will be trialling a permanent 24/7 60mph speed limit on some sections of the M1, M5, M6 and M602.

These sections highlighted have NO2 levels exceeding the legal limits. The idea is that cars travelling at 60mph is better than cars travelling at 70mph for emissions.

Surely this is slightly flawed and not really going to make much of a decrease in these levels at all is it?

I'm guessing commercial vehicles contribute the most and are already limited to 60mph or less anyway. With more EV's on the road and a trend of a growing number of EV's producing zero emissions.

So does that mean an EV can do 70mph no problem as there is no emissions issue with a zero emission EV?

So already we see 3 lanes of commercial traffic in 4 lane sections and with cars travelling at 60mph max in the only other lane. So are we not going to find a.max speed of 60mph but likely less most of the time.

I don't see that this is really an air quality issue or very good solution. It isn't a safety issue or solution. So isn't it just another stealth tax to extract fines from motorists to generate revenue?

I came home from Ashfors the other week late at night. The M25 was closed twice for two junctions and one junction. No roadworks and a combination of road sign speed limits of 40/50 and overhead gantry smart motorway speed limits of 40/50/60 in the dark flipping from one to the other is very very confusion and difficult to keep up with.

It is starting to become a bit of a joke surely and actually creating more dangerous situations. After my smart motorway speed contrevantion/fine at midnight on the M1 last year I now brake from 70mph to 40mph when I see these signs. This was advised as OK to do by the Police when I asked! Clearly not very safe.
 

CatmanV2

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I think it's more that something has to be seen to be done. What else can actually be done to reduce the NO2 levels?

Bit like lockdown, really.

C
 

Oneball

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4,054
You missed the really flawed part, the trial sections are:

“It will be on M6 junctions 6 to 7 by Witton, M1 junctions 33 to 34 by Rotherham, M602 junctions 1 to 3 by Eccles and M5 1 to 2 by Oldbury.”

Don’t know about the bit by Rotherham but I go through the other bits regularly and the chances of doing 50mph let alone 60 are pretty slim.
 

rockits

Member
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7,996
I think it's more that something has to be seen to be done. What else can actually be done to reduce the NO2 levels?

Bit like lockdown, really.

C
LOL.....very true. Just look like you're doing things. Irrelevant if they actually work or achieve anything.

Apparently some bus lane fines generate £8m a year for some councils so the potential for a little extra revenue I'm sure will be welcomed.
 

rockits

Member
Messages
7,996
You missed the really flawed part, the trial sections are:

“It will be on M6 junctions 6 to 7 by Witton, M1 junctions 33 to 34 by Rotherham, M602 junctions 1 to 3 by Eccles and M5 1 to 2 by Oldbury.”

Don’t know about the bit by Rotherham but I go through the other bits regularly and the chances of doing 50mph let alone 60 are pretty slim.
Very ironic! Surely they won't bother trying on the M25. One of the busiest roads in Europe with 250k vehicles a day.
 

mjheathcote

Centenary Club
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7,393
I experience the 60mph speed limit at 6am last week travelling down the M1, 'due to emissions'
:rolleyes:
 

allandwf

Centenary Club
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9,047
Should a car not be travelling at its most efficient to achieve this? For me I seemed to get the most mpg in the 3200 when I was cruising at 85mph. (Done in Europe.) anything much above or below then my mpg figure would drop.
 

Zep

Administrator
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4,577
Perhaps controversially, I am fine with this. My daily car will drive at 60 in electric only but needs the engine for 70.

An IC car will use significantly less fuel and therefore produce less emissions at 60 than at 70 as the cube law applies to aerodynamic losses - not withstanding engine mapping etc.

The longer reductions in emissions are concentrated around things like motorway speeds, the longer I will be able to spank my Maser on an A road.
 

Alan Surrey

Junior Member
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82
I might be wrong about the connection between a 60mph limit and NO2 emissions, but isn't it the case that NO2 is at its worst around a motorway when everyone is doing 5mph or so, nose to tail, stop start. It would be great to be travelling at 60. Perhaps they will put in a couple of extra lanes so that we can.
 

rockits

Member
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7,996
I might be wrong about the connection between a 60mph limit and NO2 emissions, but isn't it the case that NO2 is at its worst around a motorway when everyone is doing 5mph or so, nose to tail, stop start. It would be great to be travelling at 60. Perhaps they will put in a couple of extra lanes so that we can.
That's a very good point about traffic jams, accidents and random short standstills. Also actually variable speed limits as they increase emissions due to braking then accelerating.

I wonder how much excess polution is caused by traffics jams. Wonder how many sit in short or medium term jams with engines on at idle. So hundreds of cars sometimes thousands sitting there at idle in a fixed area.

As long as all the fines feed back into the road network and maintenance/improvement it all helps but it never often does it seems.
 

midlifecrisis

Moderator
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9,231
When I worked at Bournemouth Airport, we had to carry out air quality testing. Basically small upturned vials which were dotted around the campus. The worst one was by the A338, the main road into Bournemouth.
So I can see the reason for this but its so indiscriminate. Particulates mainly come from diesel vehicles not petrol maybe they should be targeted. Will Tesla's be able to do 70mph?
 

rockits

Member
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7,996
Maybe concessions and advantages need to be given to EV's to promote adoption. Even if in the real world end to end there is massive debate around whether they actually reduce emissions over a car that has already been produced.

If the narrative is about emissions then surely zero emission cars should be able to do 70mph.

Lots to say that EV restomods should be used more. The car is already there. Rip out the bit causing the issue and replace it with a new EV drivetrain. Problem is I guess retrospective fitting cost inhibits the advantage somewhat.
 

Devonboy

Member
Messages
878
From the Govts own website...https://www.gov.uk/government/publications/air-quality-statistics/ntrogen-dioxide - I cant help thinking of all the challenges our society faces today, this is not exactly high on the list....(PS spot the diesel years)

76327
 

Andyk

Member
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54,248
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 ?
 

CatmanV2

Member
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35,501
It would be a factor both of how much pollution you are emitting at each speed as well as the time you're there for.

In short if you're putting out twice the pollution at 70 as at 50, you'd need to be out in half the time. Which is not going to happen, obvs.

There's going to be a sweet spot in terms of speed vs emissions for each (probably) specific model of car and I wouldn't be surprised if it's not around 50 (because that's a sort of sensible speed average and probably leveraged by the MPG and pollution tests). ISTR reduced fuel consumption is why the US has a 55 limit?