News / Clean Air Zone
The Bristol roads with more traffic due to the Clean Air Zone
The Clean Air Zone in Bristol is pushing more cars onto nearby roads just outside the area “as expected”.
Drivers of non-compliant vehicles have been increasingly using certain residential roads more often than before the Clean Air Zone was introduced.
Despite the traffic displacement, transport bosses at Bristol City Council say air quality in these areas is still improving.
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That’s because air pollution spreads across the city, rather than staying in one particular location where it’s been emitted from a high number of vehicles.
But people living on roads that have seen more traffic will still have had to endure more noise pollution, congestion and a higher risk of accidents.
Two roads in particular, in St Paul’s and Totterdown, are thought to have suffered badly from a higher level of traffic.
The Clean Air Zone in Bristol launched in a bid to reduce harmful pollution from road traffic
The Clean Air Zone was introduced in November 2022, and over one year on the council has published a detailed report evaluating its effects so far.
Councillors on the overview and scrutiny management board discussed the report during a meeting on Thursday.
As well as displaced traffic, they also raised concerns about how the report was given to the BBC before councillors and the public; how other pollutants like particulate matter have been affected; and how accurate the data is, given some strange results next to a kebab shop.
Lower Ashley Road is split in half by the M32
Lower Ashley Road in St Paul’s and St John’s Lane in Totterdown have seen higher levels of traffic since the scheme was introduced, as drivers use these routes to avoid entering the zone.
Lower Ashley Road runs off west from Junction 3 of the M32, while St John’s Lane comes off left at the end of the A37 Wells Road — both just before coming into the zone.
Adam Crowther, head of city transport, said: “The Lower Ashley Road results show what we would expect. I live in that area as well and I’ve seen that there is more traffic using that route to avoid coming into the zone from the M32. That’s what the modelling expected.”
While nitrogen dioxide has fallen on average by almost ten per cent since the Clean Air Zone was launched, higher levels of traffic in certain areas mean it’s less safe to walk or cycle there.
Other parts of the city, on the edges of the zone, have also reportedly seen higher levels of traffic, including in Lockleaze.
Green councillor David Wilcox, representing Lockleaze, said: “I’m noticing a lot more traffic on Glenfrome Road, Eastgate Road and James Street where people are actively avoiding the Clean Air Zone. Are you intending to do any pollution testing or traffic counts on those roads that are being used as rat runs to avoid the Clean Air Zone?”
Crowther replied: “I wouldn’t disagree with that at all, it’s fairly evident. We’re not doing additional traffic counts. I wouldn’t expect that the air quality is in exceedance, but whether it’s got worse or not I don’t know, I would have to check the specific data locations around that area.
“The expectation always was that it would take some time to understand where the impacts are being felt, and then we would look to make changes to those areas. That’s why we’ve allocated £10m to mitigate any particular impacts. There’s lots of local traffic issues across the city. Some of those will have been exacerbated or created by the CAZ.”
CAZ sees the introduction of charges for non-compliant vehicles entering an area that covers the city centre, a portion of Old Market and just south of the river
So far the Clean Air Zone has brought in £26m to the council, through charges and fines, after the cost of running the scheme. This will be spent on subsidised bus routes, fixing potholes, and making it easier and safer to walk and cycle.
Throughout the lifetime of the Clean Air Zone — expected to last another three or four years — the council is forecasting it will raise a whopping £81m to spend on transport projects. £10 million of this will be kept aside for local neighbourhood transport schemes.
The evaluation report was published on Tuesday evening, January 16, ahead of an upcoming cabinet meeting. But the initial results were being reported on the television by BBC Points West at the same time that the report was published on the council’s website.
Conservative councillor for Westbury-on-Trym and Henleaze Steve Smith said: “I’m a little bit sceptical of the idea that this couldn’t be published any earlier than it was. This came out about 6.30pm on Tuesday evening, at which point Points West were broadcasting the report that they had clearly spent all day, if not longer, making.
“It went to the media while it had been held back from councillors and the public. I would like to know who made that decision — and why anybody thought that was acceptable.”
Labour councillor for Avonmouth and Lawrence Weston Don Alexander, cabinet member for transport, replied: “As far as I know the media had some details from it, but not the full report. I had some basic details of what the report was going to say, but I hadn’t seen the whole report until very recently, because I think it was genuinely still being written.”
The Clean Air Zone was introduced to tackle high levels of nitrogen dioxide, a harmful pollutant caused by petrol and diesel engines. This has reduced massively in some parts of the city, like near the Bristol Royal Infirmary, but gone up in a few other parts.
But it remains unclear whether the Clean Air Zone has also reduced other pollutants, such as particulate matter known as PM2.5 and PM10. These can harm our heart and lungs and are linked to early death.
Crowther said: “There will probably be a much smaller improvement in PM because PM is generated by a number of things, like brakes, tyres and wood burning. It would be very hard to say whether the CAZ has had a particular benefit on particulate matter. There’s a lot more sources of it.
“The CAZ doesn’t really lead to a significant reduction in vehicle journeys. A lot of particulates come from brakes, road wear, and wheels. It’s unlikely there has been a significant improvement.”
Another issue is the quality of the data on nitrogen dioxide. This is measured by many diffusion tubes dotted around the city, which are collected by scientists every now and then. One tube, on Blackboy Hill at the top of Whiteladies Road, measured a whopping 42 per cent increase in nitrogen dioxide over the first year of the Clean Air Zone.
Crowther added: “Basically, a kebab shop opened up and was sending lots of fumes to where the detector was.”
The second highest increase was next to the Galleries shopping centre. This reading shot up by 20 per cent, despite being within the Clean Air Zone. It’s unclear why this happened, and the result is thought to be incorrect. More investigation into this particular issue is planned.
All photos: Betty Woolerton
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