Access to Northampton General Hospital's A&E has been restricted to emergency vehicles only while construction begins on a new assessment unit.
Traffic wardens will be on hand to police access to the main Cliftonville entrance, in Cliftonville, off Billing Road, which is now limited to ambulances and emergency drop-offs only.
Yesterday (July 17), construction began on the hospital's new £12million 60-bed assessment unit and is scheduled for completion in nine months.
The unit will be used to care for seriously unwell patients who are transferred from A&E for further treatment and comes as part of a series of measures to redirect patients who could be more appropriately treated by a GP.
A spokeswoman for Northampton General Hospital said: "The building work will have an immediate impact for patients, staff and visitors to the site as there will be some access restrictions and changes to traffic flow on the site.
"We apologise for the restrictions the building work will place on access to the site, but we have to do this to enable the building work to continue safely. What this means is that, because of the tight confines of the site, vehicular access to this area of the site (the area outside A&E and the Cliftonville entrance) will be restricted to emergency access to A&E for ambulances and emergency drop-off only.
"All other access to the hospital, our car parks and drop-off areas will be via the south entrance at the rear of the hospital, or the entrances at Cheyne Walk and Billing Road."
The new assessment unit is being built on top of the Cliftonville car park and will result in the loss of 70 parking spaces.
To offset the loss of spaces, the hospital will buy designated staff parking from Northampton Borough Council at Midsummer Meadows car park, off Bedford Road.
A spokeswoman said: "The assessment unit is being located [in Cliftonville] so that it can be linked back to the main hospital buildings close to our emergency department and diagnostic services such as radiology. This is important because the unit is for the sickest patients who are admitted to NGH via the emergency department.
"We apologise again for any inconvenience caused."