Forum topic: Will low-traffic neighbourhoods reduce net pollution?

That should read " I am looking for data counts pre LTN on the perimeter roads...."

You'll have to ask the Council for those - I'm confident they exist as spotted the line and counters on Aldermans Hill.

My counter to your modelling was that the initial assumption is wrong; not only will x percent decide to walk and cycle journeys under 2km (and unlike you I believe they will continue to do so) but people driving longer journeys who find it's much more difficult will change their driving behaviours. As the network of LTNS grows and other measures are introduced car usage will fall - and pollution with it. In addition to a reduction in net pollution there are many other benefits - again well rehearsed. As for Waltham Forest I'm happy to accept the expert findings of the Environment Research Group at a world-class university. It's also worth looking at the many research studies of Rachel Aldred, at University of Westminster. In addition to the research on people's attitudes to LTNs, I look to actual behaviour. Hardly anyone campaigns to open up long term LTNs (it's interesting that some vehement anti campaigners live in filtered streets themselves) - indeed after a year or so the majority of residents would keep their LTN. In Waltham Forest 44% of residents were opposed at the outset : just 1.7% would scrap the scheme and revert to the original http://enjoywalthamforest.co.uk/work-in-your-area/walthamstow-village/walthamstow-village-review/

Adrian could you tell me where in Aldermans Hill you saw the lines and was this at the same time as counts were being taken inside the LTN?

I’m not specifically looking to engage on LTN’s because there’s a live trial and associated consultation underway, and I belief that’s where all comments are best served. We’re currently one of many areas sitting at the end of a big HMG LTN roll out and even if the present Johnson / Khan / Caliskan political axis becomes one of Starmer / Bailey / Laban I really wouldn’t envisage too much change in the overall direction towards less car with a commensurate focus on people.
On air quality, go back a few years on the site and you’ll see me raising the issue before it was common currency. I haven’t considered an individual LTN viewpoint because it’s systemic rather than local and so needs to be treated that way, and that to me means tackling the related traffic strand at the macro level rather than fiddling in the micro. Take out 20% of cars / journeys? Bank it. Good luck with arguing that losing 20% of UK cars / journeys will have no visible effect on air quality.
At the margin and at the very simplistic level presented, yes the maths might work but this is a hugely complex system, one that planners have tried, and failed as best I understand it, to accurately model; which remains subject to moveable externalities – Google maps being a good one, Thames Water another; and on top of all that comes human behaviour. And time itself brings change, undermining any single snap shot viewpoint: stop your short journeys and probably expect some impact on your longer journeys (and likely journeys of others) and all this overlaid with simple proxies for air quality – perhaps congestion is good for relative levels of particulates, the tyre and brake dust we breath in being that bit lower, and cut the engine and NOX doesn’t happen, but I don’t know.
I’ve earlier posted re the new London Plan, signed off by the Mayor this week. It’s the big picture we’re living in, and have been as it’s been gaining weight over the last couple of years. Its Healthy Streets based approach is evidence based. In the later 1980’s – over 30 years ago - my then boss was campaigning hard about air quality linked to the South Circular close to where he lived. Thirty years later, and with goodness knows how many extra vehicles, bigger vehicles and dirtier diesel vehicles since then, with the death of a little girl, added to research and campaigning, we might just finally see some movement. Where we’ve been in that period certainly hasn’t worked for our collective health as ever growing piles of research now point out; I don’t know if UK wide LTN’s are the definitive answer but I’m delighted someone is at long last trying to get to grips with a lifestyle choice available to some which has caused real issues for all.
I’d feed thought and experiences into the consultation – same message for everyone.

I've seen several lines across Aldermans Hill over the past few years; I recall seeing lines between Lakeside and the Zebra Crossing and also outside Venture. I think (but cant be certain) that it was same time as the LTN though I can be pretty confident the Council as traffic data for the periphery roads pre trial (and pre the planters experiment).

Karl. Thanks for your detailed reply. I agree that long term fiddling in the micro isn't going to get to the bigger picture and for me the macro approach to do anything significant for urban pollution is to get on investing in the Electric Vehicle infrastructure and stop wasting money on these local LTN schemes which will likely add to pollution. I agree if you took out 20% of ALL car journeys this would be significant but my original post was to do with the removal of a best case scenario of 55% of short car journeys that could be walked or cycled. The point being that if you have to cause the remaining traffic to do longer journeys in more congestion you will not make a saving in pollution and likely increase it. Furthermore the additional pollution is concentrated in a queuesmog. The implication of pollution as a contributory factor in the death of Ella Kissi-Debra was precisely because she lived and schooled in an area of non dispersed pollution. The LTNs are doing just this. Removing pollution from one area and adding more net pollution in a concentrated area on perimeter roads.

Adrian. You say my assumption is wrong in that although the short journey removal discussed is not enough to counter the increased pollution from the longer journeys and delays, as the maths in my model suggests, you are claiming this extra pollution will be bettered by people forgoing "longer journeys who find it's much more difficult will change their driving behaviours." Where is your evidence for this ? You are admitting the same thing on a larger scale. You have to increase the time on the road through major congestion to achieve this. How will this improve pollution figures ? Is it the plan to introduce so many LTN schemes that the A road/Trunk road system is so gridlocked that people will have to take to other transport. If so the majority of this remaining traffic will be the vehicles that have to remain including all the heavy lorries and other most polluting vehicles. You'd need to take sandwiches with you if you were going on a bus journey.
The expert findings of the Environment Research Group at KIngs were to take figures supplied to them by Waltham Forest and run them against pollution data. They were not relating the pollution data to the LTNs but to pollution maps generated for the whole of London. This survey has nothing to do with the failure of the interpretation of the raw data from the Walthamstow Village scheme and its false claim of proving traffic evaporation. Rachel Aldred's work relates to changes of behaviour in people being more active, or more likely to be more active if they are forced by LTNs to give up shorter car journeys but this is already built into my model. I am assuming 55% less short car journeys but showing the effect of this on local pollution. Rachel doesn't address pollution.
With respect to the raw data from the Walthamstow Village report, both Waltham Forest Council and consequently the reportage on BSfE suggest this proves car evaporation. They quote the reduction of cars as being 10,000 a day representing a 16% evaporation. They presumably did this by subtracting the additional figures measured on the perimeter roads (4000) from the figures disappearing from within the LTN (14000)and representing this as a fraction of all the pre LTN traffic (64000). Given that these are not numbers of cars but numbers of counts on individual roads, then each car going through the LTN would have been counted two or three times, so the original 14,000 disappearing counts probably represents only 5-6,000 cars. Some of these would have been counted on perimeter roads pre LTN before turning into the LTN so would not be included as addition traffic remaining on the perimeter roads after the LTN was introduced, as they had already been counted as cars already on the perimeter road pre LTN. Some traffic will have detoured further afield than the perimeter roads (as is happening with the Fox Lane version), which was never measured. Also traffic that never even went into the LTN area to start off with but stayed on the perimeter roads may now take a different route since these perimeter roads are now more congested so also contribute to traffic that has evaporated. It hasn't evaporated it's just taking a different route because of the additional congestion. 16% doesn’t go far to cover all these eventualities. Now it could be that some traffic did disappear but these measurements CANNOT be used to show this.

The reason I think any evaporation was negligible is that the Walthamstow scheme was introduced in 2015 and over the following years Waltham Forest introduced several other LTN or LTN type schemes yet the increase in car traffic flow for the Waltham Forest borough between 2015 and 2018 was 11.9% (416 mill miles to 469million miles from Dept of Transport stats file TRA 8902). This is not very consistent with car evaporation. Clearly there may be many other factors at play here when you look at the borough as a whole, but you might expect these to affect neighbouring boroughs as well yet Redbridge had 6.8% increase, Enfield 3.7% , Harringay 5.9% and Newham 9.6%.
So Waltham Forest must have had a lot of other cars raining in from somewhere if they were also losing loads through evaporation.
With respect to " In Waltham Forest 44% of residents were opposed at the outset : just 1.7% would scrap the scheme and revert to the original". Yes but we are only talking about people who are living inside the LTN. An area of around half a kilometre that's had £30 million spent on regeneration. They didn't survey the surrounding roads that now have the pleasure of the extra congestion and pollution.

It’s probably useful to start from where policy is and has been for a while, that is to reduce traffic volume and encourage a commensurate increase in active travel. One strong rationale has been finite city space and simply too many vehicles looking to use it. Many benefits, eg less unhealthy inactivity follow. HMG and the Mayor, from all I’ve seen and read over years, are not funding LTN’s with the primary objective of reducing air quality.
The Healthy Streets Approach outlined in this plan puts improving health and reducing health inequalities at the heart of planning London’s public space. It will tackle London’s inactivity crisis, improve air quality and reduce the other health impacts of living in a car-dominated city by planning street networks that work well for people on foot and on bikes, and providing public transport networks that are attractive alternatives to car use. It will also ensure that streets become more social spaces. (Published London Plan 1.3.4)
The point here is the focus on benefit of investment changes to people rather than where it has long been – drivers.
On air quality it’s worth not falling into traps assuming vehicle pollution and its impacts are purely localised – there’s a powerful NOX map in eg LBE’s Air Quality action plan showing it’s only the north west of the borough where levels drop to any noticeable degree, at least until getting closer to the M25; while the FT recently highlighted a map showing increased UK NOX sitting over the North Sea 5-14 November due to wind conditions. Basically it’s everywhere and we all suffer (accepting obviously not uniformly, that tends to fall to the already disadvantaged). Nor that the current (European negotiated so what could be agreed between many different pressures) legal limits of the two main metrics are “safe”, nor the WHO ones in as much as they differ. So yes, it is the macro approach we must focus on.
And on air quality it’s provably simple: if that is your desired objective then follow the mantra pushed by the UK’s leading expert on the matter – walk, cycle and if not that then use public transport and if those are not possible and you must use a private vehicle then make sure it’s as clean a one as possible. He bypasses LTN’s and goes straight to behavioural change; that’s me too, but ending 20+ years of 3000 cars daily frequently barreling up and down my street is welcome too. A lot of behaviour change there may have avoided years of bad feelings, a very widespread viewpoint I well know.
If you think this investment really is counterproductive to health then do take it up with Shapps / Khan, for a PGC web site really isn’t going to do it.