Canterbury's ring-road will be unable to cope if fresh plans for a 4,000-home estate are approved, hundreds of residents have warned.

They say the existing gridlock will be exacerbated unless at least one new railway station is built to service the Mountfield Park development, to the south of the city.

New analysis shows the expected huge rise in car use would increase delays by more than four minutes at peak times along parts of the creaking road system.

Concerned members of the Alliance of Canterbury Residents’ Associations (ACRA) also fear air pollution will worsen along major routes such as New Dover Road.

Meanwhile, they say aspects of the scheme could cause “irreversible” harm to the city’s World Heritage Site status and “must be resisted”.

In addition to the submission from ACRA – which is made up of 17 city community groups – more than 180 residents have individually responded to the resubmitted Mountfield Park plans. KentOnline struggled to find any comments in favour of the scheme.

In October last year, the city council was forced to quash its own planning permission for the development following a High Court legal challenge.

Fresh proposals for the “garden city”, which will swallow up more than 550 acres of farmland between Canterbury and Bridge, were lodged in December.

Developer Corinthian pledged to create Britain’s first “net zero carbon” community, which would include schools, office space, community buildings, sports facilities and a health centre

A raft of new measures were introduced to address concerns about drainage, affordable housing and transport. These include accelerating the provision of affordable homes, prioritising green travel and installing an on-site sewage treatment works, to prevent further pollution of the Stodmarsh Nature Reserve.

All new homes would have electric vehicle charging points and electric bikes, while Corinthian says there would be new cycling infrastructure, extensive parkland and tree planting, and an expanded fast bus service into the city with subsidised travel for residents.

But in a 38-page submission forwarded to councillors by ACRA business secretary David Kemsley, the group sets out in detail why its members remain opposed to the plans.

A key concern is the impact building thousands of new homes will have on the city’s roads.

“The huge addition to Canterbury’s roads network by cars from Mountfield Park for both the work commute and leisure will exacerbate the ongoing traffic problems,” says ACRA.

“The additional traffic generated by this development both during construction and subsequently on completion cannot be absorbed by a local road infrastructure which is already gridlocked at times throughout the day and unfailingly at peak hours during school term time.”

ACRA is urging Corinthian to “radically increase” the take-up of alternative methods of travel by subsidising or providing “a full complement of public transport services to the level that would qualify the development as car-free”.

“Any development must come with Mountfield Park train station at its heart and a clear planning condition,” says ACRA.

“This new station will help residents commute to places of work i.e. London and for leisure around Kent.

“A new Mountfield Park station could be supported by a ‘Canterbury Parkway’ station linking the East and West lines and enabling a link to the high-speed line from Mountfield Park.

“It will also help modal shift providing crucial, quick access to the city centre. Without rail links and a realistic bus plan, the modal shift projections for the proposed development lack any real credibility.”

In order to back-up its submission, ACRA paid experts from Railton TPC to carry out an updated analysis of the transport projections provided by the developers.

The consultants cast doubt on claims that train travel is expected to increase by 87% and cycling by 50%, as well as the likelihood that residents on the new estate would walk into the city centre – a distance of more than 2km, or 1.3 miles.

Meanwhile, Railton has analysed the developers’ updated transport statement and highlighted parts of the ring-road which could see longer delays as a result of the scheme.

The St George’s Street arm of the St George’s roundabout is shown to experience increases in delays during the evening rush hour of four minutes and 29 seconds.

Elsewhere, there would be an extra 61-second wait on the Old Dover Road arm of the Riding Gate roundabout during the evening peak.

ACRA is concerned additional traffic will “further place an upward pressure on air quality” in New Dover Road, which it says already has levels of nitrogen dioxide above regulatory limits.

The group also calls on the council to impose a planning condition that the development should have no gas boilers installed, instead having heat pumps and solar panels to power the homes.

ACRA says the development will result in more than 200 hectares – almost 500 acres – of open landscape being almost halved.

“In terms of water retention, biodiversity, green cover and carbon retention, this area is irreplaceable and cannot be mitigated by creating up to 30 hectares of habitat elsewhere,” they write.

“We ask you to protect the number of hedgerows providing corridors for nature to pass and roam, the badger setts, birds of prey (kites, sparrowhawks etc) hunting the field and harvest mice, voles and shrews all found on the site.”

Another concern raised is the impact the development could have on the city’s Unesco World Heritage Site status, which is described as “at risk”.

The group says the visibility of the north edge of the estate on the skyline from the Cathedral area “destroys the sense that the city rests in a rural bowl whose natural edges are tangible”.

Meanwhile, it adds the 15-metre high buildings in the community centre area would interrupt the “classic city approach view of the Cathedral from New Dover Road”.

“These cause irreversible and measurable harm, and must be resisted,” ACRA writes.

“The height parameter plan must be revised.”

With more than 1,200 documents now attached to the Mountfield Park planning application online, ACRA concludes its submission by urging Canterbury City Council to require a public exhibition be held on the proposals in their current form.

“The overall scheme because of its size, density and location so close to the city centre has major implications both for the local environment and the life quality and health of Canterbury citizens for decades to come,” says ACRA.

“CCC has a clear duty of care to safeguard residents in this regard.”

A city council spokesman said: “Holding public exhibitions or running consultation events such as the type suggested by ACRA are matters for the developer to consider and is not something we can require them to do.

“As this is a live application we cannot comment any further.”

A spokesperson for Corinthian told KentOnline that Mountfield Park “will be the lever by which Canterbury can begin to solve its traffic problems”.

It pointed to investment of £75 million in the city’s infrastructure – which would go towards a new A2 junction – and a further £30m within the development itself.

The cash would fund a cycle hire scheme for the whole city, junction improvements across Canterbury, an electric vehicle and hydrogen charging station and the electric bike scheme for Mountfield Park residents.

Cash would also be spent on a “new, expanded park and ride and Fastbus into the city centre”, subsidised buses for residents and an “on-site car club”.

It added: “This investment will revolutionise the ability of people to travel in and around Canterbury with greater ease and lower environmental impact than they are currently able to do.”