The doctors, from Marden, Riverside, and Westbury medical practices, have penned the letter to health bosses in response to proposals to relocate six of Shrewsbury's medical practices in one 'super hub' at Meole Brace.
The GPs behind the letter, who have more than 150 years of combined experience as doctors in Shrewsbury, said consultation on the proposal is vital.
A consultation on the plans is set to take place later this year.
The five, Dr Peter Bottomley, Dr Jacques Maurice, Dr Maher Moselhi, Dr Robert Park, and Dr John Williams, questioned the practicalities of a hub for so many patients – such as parking, and the impact of its Meole Brace location on access.
They said: "As regards the hub, it is self-evident it is going to be huge to cope with 40,000-plus patients. The waiting room alone will be airport lounge size never mind the car park with on some days up to 2,000 visits.
"One of the things we discovered in the surveys of years ago is that not everyone had access to a motor vehicle during the working day. Lack of transport links are obvious. Have you enquired?
"Add in unfettered access for emergency vehicles, staff parking it becomes even more congested like travelling to the retail park round the corner."
The quintet have asked for answers on parking charges, access to chemists, and if the proposals will result in job losses for practice support staff.
They have also raised concerns about the individual practice boundaries being dissolved.
They said: "It won’t take long for practice identities to be eroded. What will happen to the current declared practice boundaries?"
They added: "We appreciate the difficult times that primary care faces and you may well be lost in the detail of the plans, the sense of “noble cause” but please stop now, reach out, explain to the people of Shrewsbury and be prepared to reconsider or abandon before it’s too late.
"Shrewsbury is already in the NHS fourth division it doesn’t need to make a catastrophic error again with this experiment. The people of Shrewsbury deserve better."
Responding to the letter, Dr Charlotte Hart, Clinical Lead for the Shrewsbury Health and Wellbeing Hub, said: “We understand there are a number of queries regarding the hub proposal from patients and members of the public.
“Recent engagement sessions, which included several focus groups, have allowed us to capture the majority of the questions raised and answer them as fully as possible, given the early stages of the programme. These are available on the NHS Shropshire, Telford and Wrekin website however we will also be responding directly to the open letter to answer any additional questions.
“Information on the website is updated regularly, and any new details of the development will be communicated publicly when available, including transport solutions, the proposed services available within the hub, as well as more logistical and operational detail.
“We are currently in the pre-consultation phase, which includes conversations with patients to help inform our plans, plus we are working closely with the local authority to explore eco-friendly transport solutions to ensure the hub is accessible to our patients. A formal consultation will be held later in the year, where more information on the plans will be available, and we will be contacting each of the eight GP practice patient lists to seek their views and involvement.”