Beech Street, a tunnel which runs under the Barbican estate, was restricted to electric vehicles and cyclists in an 18-month experiment launched by the City of London Corporation in March 2020.
But when the £1.8m trial ended last September the restrictions were quietly lifted to allow petrol and diesel vehicles to use it again – and levels of nitrogen dioxide have again breached UK legal limits.
Prior to the trial NO2 levels in Beech Street had been 58.8 ug/m3 – well above the London roadside average – but fell to 19.5 when signs for the 24/7 zero emission street were erected.
They rose slightly despite the traffic restrictions being enforced by CCTV but jumped to 39 after the scheme ended, according to research by Imperial College London.
Environment campaigners say the latest NO2 levels have reached 41 – breaching the maximum by exceeding 40 ug/m3 permitted.
In a further twist, the Barbican Centre is now advising visitors that Beech Street is open to all vehicles, effectively encouraging more car journeys.
Oliver Lord, UK head of the Clean Cities Campaign, which commissioned the research from Imperial, said: “Dirty air is back on show at the Barbican.
“Reopening Beech Street to polluting diesel vehicles has led to higher levels of harmful nitrogen dioxide.
“The City’s commitment for a zero emission zone at the Barbican must be brought forward as soon as possible otherwise it is at risk of negligence by giving cleaner air and then taking it away.”
Announcing its plans for Beech Street in December 2019, the City Corporation said the road “experiences high levels of air pollution as it is a busy, enclosed thoroughfare”.
It said a “significant improvement” in air quality was expected, “resulting in health benefits for the many pedestrians and cyclists that use the street”.
It promised “bold and ambitious steps” to protect public health and said Beech Street was “just one part of the City Corporation’s fightback against air pollution”.
The scheme resulted about 930 vehicles a day using Beech Street – less than 10 per cent of the 9,500 using it before restrictions began.
A total of 34,000 penalty tickets were issued to motorists whose vehicles breached the zero emission rules.
A judicial review was brought in the High Court by opponents of the scheme but the judge ruled in the City Corporation’s favour last August.
Louise Mittal, from the environmental research group at Imperial, and co-author of the report, said: “There was a reduction in nitrogen dioxide concentrations measured at Beech Street during the zero noticeable emission street scheme that was greater than the improvement seen elsewhere in London as attributed to Covid-19 restrictions.
“This type of scheme has the potential to help Beech Street meet UK air quality objectives, whereas it has previously measured double the annual nitrogen dioxide objective concentration as recently as 2017.”
Campaigners say that, under the European Air Quality Directive, legal air levels are “not to be exceeded once attained” – placing more pressure on the City Corporation to implement new measures.
City Corporation members voted last December to launch a public consultation to make the Beech Street scheme permanent. A decision on funding is due to be taken in May.
A report to members said that, by last November, an average of 1,675 vehicles a day were using Beech Street – 18 per cent of pre-pandemic levels.
It warned: “The return of unrestricted traffic to Beech Street, even at volumes lower than pre-pandemic, will in all probability lead to a return to NO2 levels on Beech Street consistently in excess of current health based targets.”