Traffic has "doubled" and speeds are "bonkers" on a Bath street – and the clean air zone is to blame, residents say.

Volunteers have set up a speed watch in Cavendish Road and clocked speeds of up to 47mph after numerous reports of near-misses, animals being killed or injured and damage to listed buildings.

Coordinator Rachael Hushon said the group wholly supports better air quality but the road became a major north-south route after traffic lights were installed in Queen Square – a consequence Bath and North East Somerset Council was warned would happen.

The lights were installed to reduce nitrogen dioxide levels without having to charge private cars to enter the clean air zone.

Transport boss Sarah Warren said the knock-on effects could be addressed with a liveable neighbourhood that will be designed with residents in the coming weeks.

Mum-of-two Ms Hushon said: "The congestion is bonkers. Speeds are bonkers. It's just relentless.

"If Bath wants a bypass, build a bypass. You shouldn't be displacing traffic from the A4 onto residential roads.

"We have had dogs run over, wildlife killed and near misses with pedestrians. We have had lorry spillages, lorries crash into grade I-listed buildings, coaches get stuck trying to cut corners.

"We have no traffic calming measures so the rat runners love racing up and down the road.

"This situation has significantly worsened since the clean air zone traffic lights at Queen Square were turned on.

"We need change on Marlborough Buildings and Cavendish Road or a serious accident will happen."

Jaime Everard, who can see traffic queuing in Marlborough Buildings from his office, said he had predicted the impact of the traffic lights in Queen Square and asked why the council was pushing traffic from a largely commercial area to residential streets.

"I have a young child and as any parent I'm concerned for her safety, not only due to the pollutants but also due to the increased traffic and the dangers of crossing at the junction," he said.

The Cavendish Road speedwatch volunteers have clocked up more than 30 hours and persevere despite abuse on every shift – drivers have sworn at them, given them the finger and even tried to snatch the clipboard they use to clock anyone going over 25mph in the 20mph zone. Those who do speed get a letter from the police.

Julia Perryman, who coordinates another speed watch in Marlborough Lane and Buildings, said there had been a "massive" increase in traffic

"Our biggest concern is an almost complete disregard for the 20mph speed limit, and driving has become very fast and frequently very aggressive," she said.

"I myself have witnessed two collisions in the last year, both needing an ambulance to called to the scene."

Ms Hushon called for traffic calming and an end to northbound traffic in the streets so vehicles use another route.

She said many residents' associations in central Bath had supported charging the worst polluting cars to enter the clean air zone, in addition to taxis and larger vehicles.

But speed watch volunteer Robin Kerr, who chaired the Federation of Bath Residents' Associations, said when the wider city was included in a poll, just over half of the associations opposed charging cars due to the impact on poorer residents.

The council ultimately concluded that it could improve air quality without charging private cars if the lights were installed in Queen Square.

Councillor Sarah Warren, B&NES Council's cabinet member for climate emergency and sustainable travel, said: "Traffic lights at Queen Square were introduced specifically to drive down high levels of pollution in the area and to avoid even stricter restrictions across the whole clean air zone, like charging private cars.

"The first quarterly monitoring report on the effect of the clean air zone indicates that nitrogen dioxide levels are reducing in this area, which is heartening.

"However, we are committed to ensuring that the zone does not displace traffic or air pollution.

"In the report we've set out a process for dealing with specific concerns about displacement of vehicles, comparing traffic flow data with previous years to understand any changes which may require mitigations.

"Following these reports on Cavendish Road, we will review the data from the latest assessments we have been recently carrying out to see if mitigation is required in this location.

"The area is also part of our liveable neighbourhoods where co-design with residents will be starting in the coming weeks which is aimed specifically at tackling issues such as this."

Ms Hushon said in response: "Our group is fully committed to the council's air quality improvement measures but we believe that changes at Queen Square have resulted in a displacement of traffic into the heart of residential streets. This has resulted in more traffic which travels at unsafe speeds.

"Our group of volunteers, working with the police, will continue to help calm the speeds in our residential area to make our roads safer for pedestrians, especially children walking to and from school, whilst we await any mitigation measures the council seeks to put in place to stop this displaced and speeding traffic."