Forum topic: New chance to comment on Fox Lane LTN

Models – predicting, on first principles, the local atmospheric levels of gaseous and particulate emissions resulting from car exhausts under different circumstances as Peter Payne has tried to do, is difficult and will, as Karl Brown says, be subject to multiple variables in the real world, analogous to the highly complex, computer-based climate models for which the “heat dome” over the North West Pacific this summer was an anomaly. That’s why there is an ongoing interplay between the models and the experimental data. The LTN is a trial and there will be some data next year. I’m sure Peter Payne is sincere in his concerns about air quality but I worry that his arguments will be used by others for whom concerns about “the environment” are theoretical at best.
Essential journeys – there is not a binary distinction between essential and non-essential car journeys. An example of the latter might be driving a quarter of a mile to buy a pint of milk while the former would include a modified car taking a person in a wheelchair to an outpatient appointment. However, there is a spectrum between these without a sharp boundary and almost all of these journeys involve a choice. It may not feel like it in the sense that the choices have been internalised as reflexes but they are choices nonetheless. I think most would agree that an able-bodied person using a car instead of a 10 minute round-trip walk is not sensible but I accept that the closer one gets to the “essential” end, the more involved might be the choices’ outcomes and that they may not be easy but difficult is not the same as impossible.
Cycles – no, not that kind. When politicians talk about sorting things out for “decades to come” or “for a generation”, whatever their sincerity, they have an eye on the current election cycle and how the phrase will be received by the current voters - there is always a short-term element. However, we all tend to default to short-term effects. The inconvenience and irritation of a thwarted or altered drive occurs in the present and fills our thoughts while the benefits of drives not taken, both to ourselves and to other people, accrue incrementally into the future, in terms of the moderate exercise and health benefits and freeing up a space on the road for those who do actually need it.
Disasters – the LTN has twice been described as a “disaster” in these pages. This is not a disaster. Even if you don’t like it, it’s at worst an inconvenience. The floods in Canada now or in Germany in July as well as the fires in California and Australia earlier this year and last year are disasters.
Cities – there has been a view expressed that we live in a city and thus shouldn’t expect rural levels of atmospheric pollutants etc. Obviously, it would be unreasonable to expect the air quality in Palmers Green to be that of the Cairngorms. However, I’ve no doubt that, before Bazalgette, there were people who were of the view that being ankle deep in human waste and having open sewers for rivers was to be expected in a metropolis and that digging up the roads to put tunnels under them was an intolerable inconvenience. Obviously, this major infrastructure involved public money, as did the phasing out of coal-fired heating after the great smog of 1952 and at the end of over 130 years of smoke abatement campaigns ( www.historyandpolicy.org/policy-papers/papers/clearing-the-air-can-the-1956-clean-air-act-inform-new-legislation ) and as will the phasing out of gas boilers. A closer analogy is perhaps the change in behaviour involved in the use of tobacco products, particularly in public places, which has involved data, exhortation, shock tactics, nudge legislation and so on. There is also a parallel in the techniques of the industries with a financial interest in the ongoing use of these products. The basic point is that a majority accepts, however grudgingly, high levels of some pollutants until a tipping point is reached. There would not now be even moderate support for a return to smoking on public transport or in restaurants.
And finally - it is easy, when the news talks about millions of tonnes of CO2 and shows pictures of factory chimneys belching steam, to assume that no change is worthwhile before major governmental and industrial change (which clearly are crucial), so here’s another back-of-an-envelope calculation. A litre of petrol produces about 2.3kg of CO2. A car with a fuel efficiency of 40mpg which does about 10,000 miles a year therefore produces about 240kg of CO2 a month. In other words, at this mileage, each month, an average family car produces a weight of CO2 equal to the average family (roughly 2 adults and two youngish kids) or, in 6 months, its own weight in CO2.
Whatever one thinks of LTNs, there is no solution to the current climate problem that does not involve fewer car-based miles (or engine revolutions). This also includes electric cars (though clearly a better option now) at least until electricity is genuinely 100% renewable. That’s before you get to traffic volume, for which the status quo before 2020 was a straight line with a positive gradient ie increasing and not static. LTNs may be a blunt instrument but, to paraphrase the Prime Minister, “if not this, then what?”

Karl Brown, I wasn't marching for 'the right to drive anywhere', and neither was anyone I spoke to there. I was marching to raise awareness of the bad science that is LTN theory. Why do LTN supporters like yourself constantly have to resort to imputing bad faith in opponents when making their points? I don't try to misrepresent supporters' arguments; please don't misrepresent ours.

What is that 'bad science'?

John Machin - unless you’re also Peter Payne, where there has been a series of quite meaty knockabout, I didn’t. Always best not take things out of context as it can cause unnecessary problem. Please, give examples of my inputting bad faith in opponents and do note that I’d rather not be classed along with LTN supporters like myself, whatever that means, I have my own views and make my own case. By all means take up the bad science and LTN theory issue you say you have issue with; HMG, Department of Transport and GLA / TfL seem to support it. Doubtless they’ll listen to a solid case as traffic is a complex area.

It's good that the debate seems now to be moving onto more of an evidence-based basis. BS4E's analysis aims to correct for the effects of the lockdown (as far as possible) and for seasonal effects - both of which make sense.

Unfortunately, they come up with a spurious conclusion, i.e. that the LTN has achieved a 28 percent reduction in NO2. Their data does not support that.

If you observe a change in a local quantity (a reduction in pollution) and you wish to attribute that effect to a local cause (the presence of an LTN), you must compare your numbers to those from other places where that cause doesn't exist. If you observe similar reductions in pollution in those other places, then you can't claim that it was the LTN that caused the local pollution reduction. BS4E's analysis doesn't do this comparison, so I have.

I looked at two other roadside pollution monitors on or near the A406 in NE London, using exactly the same methodology as the BS4E study - comparing monthly mean (average) NO2 figures for two 14-month periods, i.e. Sept 2018 to Oct 2019 and Sept 2020 to Oct 2021.



As the graph shows, the Bowes LTN figures (bold red lines) sit fairly comfortably within the figures from the other 3 sites. The important measurement is the reduction in NO2 between the 2018-19 period and the 2020-21 period. I've not applied the small reduction that the BS4E study made to allow for the effect of less polluting vehicles over time, because I wasn't convinced by the methodology for calculating it, but it would only make about 2 percent difference to all the figures. So the raw reduction figure for Bowes is 31 percent.

What you see is that the reduction in NO2 observable in the Bowes numbers is matched by reductions at the other two sites, which suggests BS4E cannot use those numbers to claim that the LTN caused the reduction. Put simply, very similar NO2 reductions occurred elsewhere without the presence of an LTN.

Here are the NO2 reduction percentages in case you can't see the graph and table properly:

Enfield – Derby Road: 33.6 % with no adjacent LTN
Enfield - Bowes Primary: 31.0 % with an adjacent LTN
Redbridge – Gardner Close: 29.9 % with no adjacent LTN

The roughly 30 percent reductions are a good news story in themselves, of course, and need explaining. But the Bowes reduction cannot, on BS4E's evidence, be attributed to the LTN.

Well, here's what you said in post #6237 :

19 Nov 2021 09:23 #6237
Karl Brown
I’m delighted that our deadly air quality levels and several associated pollutants now have such awareness and concern. That, when only seven or so years back, after several sessions with leading researchers in town understanding the then silent problem, posts here and letters to the local press to raise awareness were met with a spectrum from disbelief to disdain. Our world has certainly moved far in a short period of time. However I doubt if marching for the right to drive anywhere to save the planet will cut it with any thoughtful observer, even were it not the week after COP26 with the highlighting of carbon associated catastrophes and need for fundamental lifestyle change.

There'd been discussion of the local march earlier on in the thread, so how was I getting you out of context? What is 'marching for the right to drive anywhere' if not an imputation that the marchers are selfish? Do please explain what you really meant, though I don't see what other interpretation anyone could put on your words, in the context of a debate over LTNs.

John Machin, very much Peter Payne focused and very much linked directly a long exchange we have been having. If you choose to take a debate between two out of its framework and into some general all-person sphere than I can only suggest not to. PP was specific in why he was marching. If, and then why specifically you – and others - marched I have no idea and nor would assume.
PP has long been undertaking extremely detailed pollution based analysis. He clearly, and rightly in my view, has a real concern of its impacts and is then developing an argument against LTN’s based on same. He believes his numbers, sees them as proving a powerful adverse environmental result of the Fox Lane LTN and said he was marching on that basis. My counter view, as expressed, is that such is the huge range of variables and inherent complexity that there can be no effective definitive answer; there will always be an alternate boundary line capable of being drawn, future uncertainty vs past data, and much more. 47 rather than 42 as some might think of it. So while not perfect, the simple traffic data count I believe is to be used in the final report should be adequate for what is needed. I‘d expect we will see a better position for some streets a worse position for some roads, but best wait and see.
A better outcome for pollution based concerns would be if efforts were channelled into extending the ULEZ to the M25 rather than having a single LTN focus – my view.

Fair enough, sorry if I butted into a longer discussion but it is all on a public thread.

You believe the issue is all too complex to calculate, but if true that cuts both ways, of course. Councils shouldn't then be spending scarce time & resources on schemes whose outcomes are impossible to measure. In the absence of a reliable method of assessing the impact of what you do, 'first do no harm' would be the guiding moral principle. And if you can't measure harm, logically the only way to be sure of doing no harm is to do nothing.