Building a new £600m 'super hospital' on land at junction 8/9 near Holyport would be the wrong decision, according to Royal Borough councillors who represent the ward.
Dr Phillip Lee is behind the vision to create the new Royal Thames Valley Hospital which would see existing healthcare services merge onto one site.
But in an open letter to Dr Lee, councillors David Coppinger (Con, Bray), David Burbage (Con, Bray) and Leo Walters (Con, Bray) stress the land off the M4 is unsuitable for a new healthcare facility.
"It is right to have the hospital but with the current road systems it is not the right place," said Cllr Coppinger, who is also cabinet member for adult services and health.
He pointed to existing congestion on the A308 and A330 during peak times and the pending arrival of Crossrail to the town as reasons why the land at junction 8/9 is inappropriate for the development of a hospital.
"It really has got nothing to do with nimbyism," added Cllr Coppinger.
"It is not realistic with the current amount of traffic and no-one knows what's going to happen over the next five years."
In addition to hosting the agricultural Littlewick Green Show each year, the site is also situated in floodplain and greenbelt land.
In the letter, published in the Advertiser on Thursday last week, it says Dr Lee is premature to decide upon junction 8/9 as a preferred location and urges him to look at alternative sites such as land around junction 7.
Leader of the council and chairman of the cabinet, Cllr Burbage, warned if Dr Lee gets his way it would lead to an 'intensification' of the area and have serious effects on Bray parish.
He said: "There is pressure on all greenbelt land for development so that's why we have to make sure we stand up for local people."
Top Ten Articles