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Levels of motor traffic nearly halved within London LTNs, new study finds

Researchers who analysed dozens of schemes across 11 boroughs say little evidence of traffic being displaced onto surrounding roads

A new study on low traffic neighbourhoods (LTNs) introduced in London in 2020 and 2021 has revealed that motor traffic levels within those zones fell by almost half, but found little evidence of such schemes resulting in traffic being displaced onto surrounding roads, a claim regularly made by opponents of such initiatives.

Conducted by the University of Westminster’s Active Travel Academy, the study was commissioned by the climate change charity Possible, which says it is “the biggest ever study into the impact of LTNs and the evidence is in: they work.”

Researchers analysed traffic data relating to 46 LTNs in 11 boroughs across London. The boroughs (and, in brackets, the number of schemes) analysed were Hackney (11), Islington (6), Brent, Camden, Lambeth, Southwark (5), Waltham Forest (3), Enfield (2), Greenwich, Hammersmith & Fulham, Newham (1), plus one LTN straddling the boundary between Newham and Waltham Forest.

They found that there had been a mean reduction in motor traffic within the schemes studied of 46.9 per cent, with two thirds of the LTNs studied now seeing fewer than 1,000 vehicles a day, compared to two fifths of them beforehand.

The study found that, contrary to one of the claims commonly put forward by opponents of LTNs, that the data did not suggest that motor traffic had increased on the roads surrounding them, with an increase of less than 1 per cent of the mean average of vehicles there.

The average decrease in motor traffic inside LTNs was almost 10 times higher than the average increase in it on the roads around them, which Possible said “suggests that not only do LTNs have substantial benefits inside their boundaries by creating an overall reduction in traffic, but they can also contribute to wider traffic reduction goals.”

> Low traffic neighbourhoods encourage a quarter of Hackney’s residents to cycle more, poll finds

Possible said that the study “shows that most streets within low traffic neighbourhoods see reductions in traffic, improving the experience of walking and cycling.

The charity underlined that the report “emphasises the need to consider that boundary roads are still highly likely to still be polluted, unsafe, or difficult to cross or cycle on.

“Removing LTNs is unlikely to alleviate these issues so it is vital for local authorities to consider other measures that could (such as expanding low emission zones, urban greenery, increasing public transport provision etc).

“In this climate crisis, we need our policymakers to make bold, data-led decisions; this report gives them that information.

“Now we need action to drive down traffic, make our cities happier and healthier, and directly address the climate crisis.”

Saying that the schemes “are good for people and planet, “Possible urged councils “to use the report’s findings to introduce more LTNs and to challenge misinformation about the direct impacts on boundary roads as well as to call for further measures to address traffic on these boundary roads.”

While LTNs, which use filters to stop residential areas being used as through routes to avoid congestion on main roads, while allowing access to people who live within them, have been around for decades, they came to prominence during 2020 as a number of councils across the capital introduced new schemes as part of their response to the coronavirus pandemic.

Hackney, Islington and Lambeth were among the most active London boroughs in rolling out new LTNs, despite opposition that included vandalism of both CCTV cameras and planters and bollards used as filters, as well as legal challenges being mounted, unsuccessfully.

> High Court judge rejects challenge to Lambeth’s Low Traffic Neighbourhoods

In some cases, councillors even received death threats, and LTNs in Hounslow were claimed by one local politician opposed to them as creating a situation comparable to that in apartheid-era South Africa.

> Tory councillor apologises for comparing LTNs to South Africa’s apartheid era pass laws

Elsewhere in the capital, some councils did not introduce any LTNs at all, while in Ealing in west London, the Labour-controlled council halted plans to introduce them across the borough and removed several that had already been put in place as a result of opposition that included the Labour MP for Ealing Central and Acton, Dr Rupa Huq.

Simon joined as news editor in 2009 and is now the site’s community editor, acting as a link between the team producing the content and our readers. A law and languages graduate, published translator and former retail analyst, he has reported on issues as diverse as cycling-related court cases, anti-doping investigations, the latest developments in the bike industry and the sport’s biggest races. Now back in London full-time after 15 years living in Oxford and Cambridge, he loves cycling along the Thames but misses having his former riding buddy, Elodie the miniature schnauzer, in the basket in front of him.

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hutchdaddy | 1 year ago

Shock! Horror!

Well thought out plans to reduce traffic, make the roads safer, improve the environment and reduce pollution actually work!

Well that'll be reason enough for some twat somewher to call for their removal.

the little onion | 1 year ago

Some thoughts

-it's not (yet) peer reviewed, so it's more like a preliminary study. Though this isn't to dismiss it out of hand. It is the first, as far as I know, large scale counterfactual causal-inferrence based study of LTNs

-The sample is actually quite large - 500+ monitoring points

-the methodology is reasonably robust - there is accounting for general trends in traffic across london, e.g. COVID, though as far as I can see, not adjusting for more local trends (e.g. differences between north and south london, though there is accounting for trends between outer and inner). There might be methodological problems with doing this, and we are getting a bit technical.

-A key paragraph from the summary is this "But while the overall picture on boundary roads is of little change, there is substantial variation in both directions, with many LTN boundary roads showing a much larger rise or fall in motor traffic than the median or mean values. We consider that large declines or increases in boundary road motor traffic are unlikely to be primarily caused by LTNs. They may instead point to the impact of individual contextual factors such as local major works, or the distinctive character of a specific road or area relative to wider background trends. The strength of aggregating across so many schemes is that such potentially exogenous factors can be ‘averaged out’ to aggregate overall impacts of LTNs in general across London."

This means that although traffic INSIDE LTNs went down by pretty much the same amount in all LTNS (sensitivity analysis), there was very divergent experiences in the boundary roads. Overall, traffic stayed about the same, but other factors clearly played a part. Which means that:

a) there is truth in the fact that some people have seen traffic on boundaries increase post-LTN (and relative to a counterfactual). Some objections have a grain of truth.

b) Attributing this to the creation of the LTN, and not some other factor, is problematic. So correlation is not causation, and the chances that it is due to LTNs, compared to other factors, aren't great. 


Again, this is one pretty decent study, and it has some interesting findings. It points quite convincingly in a certain direction, that LTNs are good. But more data, or analysis done differently, may add to the picture.

ShutTheFrontDawes | 1 year ago

Taking a bit of a negative spin on the article, I'm pretty disappointed to see that the implementation of LTNs results in such a small decrease in traffic -only 46.9%.

I had hoped that LTNs would be more of a silver bullet for reducing traffic on minor roads.

Rendel Harris | 1 year ago

This absolutely accords with my experience of my local LTNs (Oval, Railton Road and Dulwich); I actually use the boundary roads (Harleyford Road and A3 for Oval, Coldharbour Lane and Milkwood Road for Railton, East Dulwich Grove for Dulwich) far more often than I actually venture inside the LTNs and I have not noticed any increase in traffic volume on any of them.

jaymack replied to Rendel Harris | 1 year ago

The problem with LTNs is that they're a gateway policy. One moment the government, local & national, is tinkering with a little harmless traffic calming scheme, the next thing you know all travel policies are fact based with the health of the nation & planet at their heart.

Rendel Harris replied to jaymack | 1 year ago

Oh lord, I never knew that. That's evil, I'm going out to set fire to some planters.

OldRidgeback replied to Rendel Harris | 1 year ago
1 like

I use those LTN routes too, Railton Rd in particular. And I agree that Coldharbour Lane is as bad as it's alwas been. The South Circular has always been pretty bad and is no better or worse than before.

But since traffic through Dulwich was controlled, Croxted Road has definitely become worse.

AlsoSomniloquism replied to OldRidgeback | 1 year ago

Oldridgeback, I seem to remember you had concerns about one LTN and a potentially dangerous junction near you? Were your concerns valid? Did the issues continue or ease off? (Might well have been the Croxted Road you mention).

OldRidgeback replied to AlsoSomniloquism | 1 year ago

The LTN I have concerns about is the one in my street. Yep, it's been good for residents but it has made the junction at Brixton Water Lane, Effra Rd and also nearby Josephine Ave more dangerous. There have been a few RTCs since the change. The council is now looking to change the junction because of the danger to schoolkids in the morning as I predicted. I can't help thinking having another entrance to the main road system one reduce the risk, just as I've thought all along. 

Rendel Harris replied to OldRidgeback | 1 year ago

I virtually never ride down Croxted and certainly not during rush hour so I haven't seen it but that certainly chimes with the fact that it seems to raise the most complaints. I wonder what would happen if you made Croxted one way in one direction and Rosendale one way in the other?

OldRidgeback replied to Rendel Harris | 1 year ago
1 like

Rendel Harris wrote:

I virtually never ride down Croxted and certainly not during rush hour so I haven't seen it but that certainly chimes with the fact that it seems to raise the most complaints. I wonder what would happen if you made Croxted one way in one direction and Rosendale one way in the other?

Making Croxted Rd and Rosendale Rd one way wouldn't be a good idea at all. You'd have a lot of traffic along Rosendale Rd and remember that there's a big primary school there, so not a safe move for the morning.

I go the other way along Croxted Rd from the busy traffic on my commute so I don't get stuck (and I'm on two wheels anyway) but I understand why people get irritated.

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