Earl Spencer's plans to build fourteen homes on a wildlife site in Northampton face opposition from residents and a borough councillor.
The estate is earmarked for land off Mill Lane in Dallington that used to be the old tennis courts.
Twenty-one letters of objection have been received from neighbours, with many referring to perceived danger posed by a new road layout.
Councillor Gareth Eales said Mill Lane already suffers from traffic safety issues and worsened, he believes, by the Fitness First car wash.
He said Mill Lane would have to be reduced to 30mph to make the proposed junction safe.
He said: "To add this extra junction onto Mill Lane would be an accident waiting to happen.
"The Woodside Walk junction nearby is dangerous enough, and that has a mini roundabout. For highways reasons this is a non-starter, for me."
In the planning application, Northamptonshire County Council Highways says the road scheme will be safe: "The submitted details demonstrate appropriate visibility and tracking of vehicles can be achieved."
The application, which is recommended for approval, has been submitted by Earl Spencer via trustees of 'The 8th Earl Family Settlement'.
An application for seven homes at the site was previously approved on appeal back in 1987 but lapsed without a brick being laid.
Councillor Eales backed the views of objecting residents over decreased security to their homes and the loss of an area of flood plain.
The land is a wildlife site, albeit not accessible to the public, and some also lamented the loss of a haven for snakes, swans, herons and deer.
Councillor Eales said: "As both the local borough and county councillor, I have no hesitation in opposing this application and absolutely will stand by residents in this regard.
"It is worth the planning department noting that Earl Spencer has had previous such applications for this area turned down for some of the exact same reasons, so I hope we will do so again."