Offenders could be double-bunked in Christchurch's new central police station because it has far fewer cells than the old building.
However, police say there will be stringent rules in place so serious criminals are not put in the same cell as low-risk or first-time offenders.
During a tour of the single-storey St Asaph St building yesterday, Canterbury district commander Superintendent Gary Knowles said the facility had 20 cells, 16 of which will sleep two prisoners, meaning there will be double-bunking.
This gave the new station capacity for 36 prisoners at one time, but there were also some day rooms that could hold several prisoners.
The Hereford St station had 55 cells, which had almost reached capacity in recent months.
Custody suite manager Senior Sergeant Neru Leifi said weekend arrests, from 5pm Friday to 6am Monday, had risen dramatically since a liquor ban operation started on October 1 - from the normal 130 to about 200.
The operation officially finishes at the end of the year, but will continue in a modified form until March.
Leifi said overcrowding at the new station's cell block had been "assessed as a risk", but police would "work through that".
One option was having more staff working in the custody suite to process offenders faster, he said.
Knowles said police would "manage" the reduced capacity through its new operating procedure.
He said research showed double-bunking, used at Counties Manukau and Rotorua stations, reduced cases of suicide and self-harm.
The U-shaped design of the cells meant police could watch prisoners at all times.
Triage nurses would be working around the clock.
Central area commander Inspector Derek Erasmus said double-bunking was "a double-edged sword".
"There is some evidence it is safer for prisoners in that they are less likely to suicide or self-harm. Alternatively, you could get prisoners fighting each other," he said.
"We're just going to have to be very careful as part of our new operating procedure to make sure we are making the right decisions when we put two prisoners in one cell."
The cells and custody block will remain at the present site until late January. This was because police expected New Year's Eve to be "the busiest night of the year" and police wanted to be able to operate "in an environment we are familiar with", Erasmus said.
The Southern Communications Centre moved into the new station yesterday.
Much of the 7500 square metre building is still being fitted out. Six hundred staff, including 48 Department of Corrections officers, will work out of the building once it is completed by February.
- The Press
Should residents do more to help maintain the city's parks and reserves?Related story: Christchurch citizens to mow parks?