Civil Defence is planning to reduce the cordon around central Christchurch to one-fifth of its original size over the next few weeks.
National controller Steve Brazier says zone five will be opened to residents and business owners in the earthquake-hit city on Monday and to the public on Tuesday.
Zones four north, six, seven and eight will then be opened progressively during the first half of April. Unsafe parts of the zones will be fenced off.
Mr Brazier says one of the reasons for reducing the cordon is to ease traffic congestion.
He expects that business owners will be allowed to retrieve important items from the worst-hit red zone, under supervision, on Monday.
Civil Defence is doing a stock-take of the red zone to ensure buildings with red stickers have been correctly categorised.
Mr Brazier says where possible, broken doors and windows are being boarded up.