Closing the A&E unit at Huddersfield Royal Infirmary will send an extra 35,000 patients a year to Calderdale.
Calderdale Royal Hospital’s A&E currently receives 70,000 patients annually.
And doubts have been expressed about the number of people who would be seen within the community at local health centres and pharmacies to ease the A&E burden.
The figures were revealed before a Kirklees and Calderdale health scrutiny panel by local NHS chiefs behind the Right Care Right Time Right Place plan.
The proposal could close Huddersfield’s A&E and centralise emergency care in Halifax, leaving Huddersfield without full emergency services.
WATCH the trip from St George's Square to Calderdale Royal Hospital below
Urgent care centres, which will treat non life-threatening cases, will be opened at both sites.
And it is expected that approximately half the patients currently attending the two A&Es will be treated at urgent care centres on both sites.
Huddersfield and Calderdale A&E chief Dr Mark Davies said: “At the moment about 70,000 patients attend A&E at Huddersfield each year.”
Scrutiny panel chairman and Calderdale councillor Malcolm James commented: “So 35,000 people will be going to Halifax in addition to the Halifax attendances as it now stands?
“That 35,000 just seems to be a very high percentage (rise).”
Dr Davies said: “We estimate that approximately 50% of patients who currently attend the emergency department at Huddersfield would be seen at the urgent care centre.”
But panel member and Calderdale councillor Adam Wilkinson expressed concern that the hospital shake-up did not appear to be reducing the number of patients attending hospital.
Clr Wilkinson said: “Surely the whole point of these proposals is to reduce pressure on hospitals?
Take a look at the Huddersfield Examiner's Battle Bus stuck on the bypass between Huddersfield and Halifax below
“If 50% of people, who are now going to Huddersfield A&E, still go to Huddersfield and 50% still go to Calderdale, surely the whole thing is failing because you haven’t reduced pressure on the hospitals at all?”
But Right Care Right Time Right Place chief Dr Steve Ollerton said Calderdale Royal Hospital (CRH) would be able to cope with the additional influx.
Dr Ollerton said: “If you take the 70,000 that currently attend CRH and add another 35,000 then that would be the worst case scenario and that’s still well within what quite a lot of A&E departments cope with at the moment.
“But our intention is there would be fewer than that attending.”
Protesters fear car parking with be completely inadequate at Calderdale Royal Hospital, but health chiefs hope funding from the Government would include enough for a multi-storey car park.