An independent review has warned of “significant uncertainty” about how effective Bath’s mooted clean air zone could be.
Bath and North East Somerset Council initially proposed charges for all high-polluting vehicles in a bid to cut nitrogen dioxide levels “in the shortest possible time”.
After further modelling and a consultation that attracted 8,400 responses, the authority concluded that it could improve Bath’s air quality without charging private cars.
After claiming power from the Conservatives earlier this year, the new Liberal Democrat administration commissioned a £9,000 review of the conclusions that cast doubt on the modelling – specifically around the emissions from lorries on Bath’s hills.
Consultants SNC Lavalin said the proposed clean air zone and an option that included charges for cars had not been compared “on a common footing”, warning that may “unduly add uncertainty to the identification of the preferred option”.
It said: “Given this degree of uncertainty, it is unclear whether the preferred option as defined in the outline business case is actually ‘likely’ (rather than just ‘possible’) to ‘achieve compliance in the shortest possible time’, thereby increasing the risk of potential challenge to B&NES Council’s current clean air plan.”
Another source of uncertainty is down to the lack of “real world” evidence of what drivers faced with a clean air zone charge will do – whether they will pay up, upgrade their vehicles, use public transport or re-route.
SNC Lavalin said it was unclear what B&NES Council would have to do if the clean air zone failed to bring nitrogen dioxide within legal limits, and recommended drawing up a contingency plan.
B&NES Council officers said if it fails to improve air quality, it could be forced to pay a share of any fine levied against central government for non-compliance by the European Court of Justice.
But they said it was unclear how Brexit will impact on that threat of fines.
Cabinet members will be updated on the clean air zone when they meet on 12th September.
They will be asked to approve the costs of implementing the clean air zone, which will include the installation of cameras and signage, traffic management and mitigation measures.
The total cost of almost £18million is set to be funded by central government.
The cabinet will also be asked to approve the appointment of a partner to administrate finance packages to help businesses and individuals affected by charges with non-compliant vehicles to upgrade.
The report seeks authorisation for anti-idling enforcement powers and weight limit restrictions to further reduce emissions and avoid rat-running.
The boundary of the clean air zone has changed several times since it was first proposed in response to residents’ concerns. Sydney Wharf, Raby Mews, Sydney Mews and parts of Raby Place/Bathwick Hill have now been added in a bid to reduce camera “clutter” and align with a residents’ parking zone.
A consultation on the final details of the scheme will run from 23rd September to 20th October.
A full business case will then go before cabinet members on 5th December, before being submitted for final approval by Government.
The clean air zone will be launched at the end of 2020.
High-polluting taxis and vans will be charged £9 a day to enter it, while for buses, coaches and lorries the cost will be £100.
There will be no charges for private cars or motorbikes.
Council leader Councillor Dine Romero said: “Achieving compliance with air quality across Bath will result in widespread health improvements as well as playing a significant part towards changing the way people travel around our city.
“The review was undertaken to ensure there were no missed opportunities and the modelling was robust and I am reassured by the outcome of the review which says the scheme has the potential to achieve compliance.
“We are on track for the full business case to be brought before cabinet for a decision in December.
“As we have repeatedly said, private cars will not be charged and we now want to go out to the public with a final consultation to fully explain how the zone will work and what support will be available.”
Stephen Sumner, Local Democracy Reporter