"So it's presenting a real danger. There have been large boulders still coming down on to the road today.
"Until the engineers can think of a way of stabilising the bluff, there's no way we're going to reopen that road.
"That may involve getting rid of large pieces of material up there."
Two houses have been evacuated after being affected by slips, one in Aro Valley and another in Evans Bay.
Those will remain evacuated until at least early next week.
"The property owners have to get engineers to look at the slips and the foundations of the house, to make a call on whether they're safe or unsafe," MacLean said.
"For the Devon St house, the landslide took out its sewer connections and possibly water supply as well, so it's uninhabitable until those connections can be fixed."
The council and geotechnical experts have checked other houses near the slips, and have decided there's no current danger to the surrounding homes.
But MacLean warned that Wellington drivers should keep speed down and stay alert, as there was a risk of landslips, rocks, or boulders, being around any corner.
Wellington Civil Defence controller Bruce Pepperell said the city had taken a hammering with recent severe weather.
"We've had 166 per cent of our normal rainfall for July.
"So it is quite saturated out there, and it doesn't take much to get parts of the soil breaking away."
This winter the capital's suffered more than 450 slips across the region, leading to problems with roading and housing.
GNS Science records show land slips are more deadly in New Zealand than earthquakes or tsunami.
