Dave Hill: What effect has the expansion of the London ULEZ had so far?

Dave Hill: What effect has the expansion of the London ULEZ had so far?

Yesterday Sadiq Khan hailed a Transport for London report about the effects after six months of his vast, 18-fold expansion of London’s ultra-low emission zone (ULEZ) on 25 October last year, saying it showed what an “incredible difference” his policy had made.

The London Assembly Conservative group was less impressed. That will come as no surprise, but the BBC’s coverage of the report was downbeat too. Its website headline read: “ULEZ expanded zone has had limited impact so far, TfL report says.” What are we to make of these differing characterisations of TfL’s assessment?

Here’s a radical idea – let’s look at the report itself.

It is a dense and rather technical 52-page document whose findings are presented with many caveats and qualifications. The first thing you notice is that it also examines the impact of the much older and London-wide common-or-garden Low Emission Zone (no “ultra”) in the full year since its strictures for heavy vehicles were tightened in March 2021.

The LEZ (as it’s known to its friends) is the oldest of the capital’s “emission control” schemes and was introduced in 2008 by Ken Livingstone. It charges non-compliant vehicles £100 a day, or £300 a day for the heavy ones. The LEZ and the ULEZ operate in conjunction, and for most large and heavy vehicles the standards they set are now the same. Owners of non-compliant cars, vans and motorbikes and other lighter vehicles that drive within the ULEZ must pay a daily charge of £12.50.

What has changed within the expanded ULEZ zone since its introduction?

Table 3 (page 15) shows that prior to its 25 October launch 950,000 vehicles were seen driving in the zone, of which 124,000 were non-compliant with ULEZ standards.

In May of this year the number of vehicles seen was 929,000 of which 57,000 were non-compliant.

It’s worth pointing out that the decline in the overall number of vehicles has not been steady – for example, in January the number was 862,000 and in March it was 931,000 – and neither has the number of non-compliant ones, though the non-compliant percentage has been fallen throughout and the compliant percentage has, of course, ticked up in parallel from 86.9 per cent to 93.8.

But what about air quality, the improvement of which is the principle goal of the ULEZ and LEZ? A “key finding” states that “people in the zone are breathing cleaner air” as a result of the change in the size and compliance composition of vehicles in the ULEZ, though this refers only to roadside nitrogen dioxide (NO2) concentrations, which the report says are 20 per cent lower in inner London “than they would have been without the ULEZ and its expansion”. NO2 is also said to be down alongside boundary roads.

Does that degree of change merit the Mayor’s “incredible difference” claim about the effects of his policy?

Those effects aren’t straightforward to quantify. In a section headed “limitations of the analysis” (page 12) the TfL report records that the pandemic years of 2020 and 2021 saw people’s travel habits change compared with previous years, with traffic volume levels falling, especially in central London. “This will in turn have impacted pollution levels across the city,” the report says. The fuel shortage of autumn 2021 was another unusual factor and has been followed by the cost of living crisis. Result?

These factors mean that traffic patterns for the period 2020 to present are not as usual or comparable to previous years, which consequently affects emissions data and hence pollution concentrations. This makes it difficult to definitively attribute changes in emissions and concentrations to the impacts of the ULEZ, its expansion and changes to the LEZ. However, compliance rates remain a robust indicator of the impact of the scheme.

This section has been highlighted by the London Assembly Conservative group, which has also long argued that the costs – financial and social – involved in enlarging the ULEZ do not justify the beneficial impacts, and that the same will be so of the Khan’s wish to expand the ULEZ to cover the whole of Greater London next year.

Nick Rogers, who leads for the Tories on transport, says ULEZ expansion would be better spent on something else, and the general Tory view is that people would have sold their old and and very polluting cars and bought cleaner ones in any case and will continue to do so without needing the incentive of a ULEZ fine. They also maintain that poor and disabled people will be hit hardest, as they are the least able to buy cleaner vehicles. Rogers contends that the case for further ULEZ expansion is getting “wobblier by the day“.

The issue is likely to be raised at tomorrow’s Mayor’s Question Time session, including by the Assembly Greens who – again as you would expect – do not see things the same way as the Tories. They believe the six-month findings show that Khan  is quite right to want to go further with the ULEZ, but that the initial enlargement should have encompassed the North and South Circular roads rather than stopping just short of them, and that the pretty small overall reduction in vehicles of all kinds traveling within the zone means there’s been a negligible effect on the other form of air pollution – PM particles, which are the microscopic bits of grease and tyre motor vehicles of nearly all types discharge.

The Mayor might not accept the Green critique, but he nonetheless seems set to stretch the ULEZ beyond inner London to cover all of the metropolis before the next mayoral election in 2024.

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Categories: Analysis


  1. Tony Woolf says:

    Pollution levels are too high, and my grandchildren are breathing polluted air on their daily walks to and from school, when part of their route has to be on a main road. In general, that pollution is really hard to control as it comes from many sources; for example in air flows from abroad and from domestic gas central heating. But we have a measure for tailpipe vehicle emissions and can control them. I can’t believe that we shouldn’t do it when the practical alternative seems to be doing nothing.

  2. Oscar says:

    My main problem with the ULEZ is the arbitrary cut off at midnight. A band I know drives in to their gig in London. It’s a gig at a small but thriving music club showcasing unsigned talent (and therefore doesn’t pay well) and therefore can’t afford a newer vehicle capable of bringing them and instruments. Because they enter the zone at 5pm and leave at five minutes past midnight they are charged two days, while someone in a similarly polluting vehicle can arrive at 6am and leave at 8pm, having driven all day making deliveries and creating pollution, and be charged half as much. Surely it wasn’t the intention to penalise London’s essential but dwindling grassroots nightlife?

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