Thousands of motorists could be facing long journeys and added costs for up to four weeks following the closure of the main Opotiki to Gisborne highway.
The stretch of State Highway 2 connecting Opotiki to Gisborne has been closed following a slip in the Waioeka Gorge.
Those looking to make their way between the two eastern locations face a detour using State Highway 35, around East Cape.
The coastal route adds more than two hours to the journey. Online maps for the area place the State Highway 2 route between the town and the city at one hour 45 minutes, whereas the State Highway 35 route takes an estimated four hours.
The section of road could remain closed for up to a month, after inspections estimated the clip could be as large as 100,000 cubic metres, said New Zealand Transport Agency acting Bay of Plenty state highway manager Andrew Scott.
The amount of debris and matter strewn across the road means it would take much longer to move than first thought, and stabilisation work will need to be completed before the gorge can be re-opened to traffic, he said.
"We need to be satisfied that the Gorge is safe for drivers to use, so while we're clearing slip material we'll also be determining the best cause of action to stabilise rockface areas that could have been weakened by the slips."
Gisborne mayor Meng Foon estimated thousands of motorists, businesses and trucks would be affected by the closure of the main highway route.
"It's very disruptive to everybody that goes through the gorge, especially the produce that's coming in and out. Everybody will have to take the long way along the East Coast or through to Taupo, coming up from the south, so huge disruption.
"All of our businesses use the road. I would say there's thousands of cars and trucks that actually go through, from logging trucks to freight carriers, even sometimes people have to visit hospitals in Waikato. There's going to be huge inconvenience for a lot of people."
He said the longer distance for road users would result in added costs.
"Of course there's going to be a financial impact. Even people having to take the long way round, it's going to use more fuel and that sort of stuff, plus some of the goods that haven't been able to get through. People are going to have to wait."
He said although the gorge had suffered many closures from slips in the past, no long-term solution was being looked at.
"It's an acute gorge, there are rock-slides constantly in different degrees coming down the hills. So I think they just fix it as it comes. Personally I don't think there's anything you can do about mother nature."
Federated Farmers Gisborne president Hamish Cave said livestock was frequently transported along the route from Gisborne to meat plants in Bay of Plenty or Waikato.
He said the closure would "certainly" cause disruptions to the livestock industry, but he could not place a dollar figure on the disruption.
The gorge has been plagued by slips in the past. Slips caused by wild weather forced the road to close in late January last year, and in May 2010.