A Manawatu-Whanganui regional councillor says the Manawatu Gorge road must be retained as alternative routes on offer are not adequate.
The Transport Agency has confirmed State Highway 3 through the gorge will stay closed for at least two weeks because of a landslip on Thursday.
Another major slip in 2011 closed the gorge for nearly a year.
John Graham, of Palmerston North Mainfreight Transport, has questioned the long-term viability of the Manawatu Gorge, saying the terrain meant there would always be problems.
Upgrading Pahiatua track or Saddle Road to serve as the main route between Manawatu and Hawkes Bay could be a better long-term investment, Mr Graham said.
But an agency spokesperson said the gorge road was preferred by most truck companies.
The agency said Saddle Road was identified by the Manawatu-Whanganui Regional Council's transport committee as the primary detour and it had already spent almost $10 million on a major upgrade.
It said the upgrade was only half done but was already proving its worth as a detour route when the gorge was closed.
But it was important to remember closures of the gorge were uncommon, it was shorter than the alternatives, and an easier drive.
Gorge road an important link
Councillor John Barrow, who represents the Tararua constituency, said the gorge road was an important link for Tararua communities.
"It is critical for the township of Woodville in particular, and Woodville has become a satellite for Palmerston North now - a lot of families living in Woodville travel through to Palmerston North each day.
"And of course for the Tararua and the east coast in general it is the main road that links the lower central north island with the east coast."
Mr Barrow said heavy traffic through the gorge might be taking a toll on surrounding hillsides, with more slips now than before.
But he said the Pahiatua Track and the Saddle Road north of the gorge were bypass routes at best.
He said cars could handle them but truck drivers would struggle with a slow haul up the hills.
Mr Barrow said the agency needed to do whatever it can to keep the gorge open.
More problems found - NZTA
The Transport Agency's regional performance manager, Mark Owen, said the slip was small and the debris had been cleared, but a geotechnical engineer had found further problems.
"It's created a bit of an under-slip so there's rocks that are up there that are now exposed, there's tension cracks that have been identified."
Specialist equipment would be brought in over the weekend, Mr Owen said.
"It could take up to about two weeks for them to get in there and remove all those rocks to bring it back to where we feel it's a lot safer for motorists."
The slip happened about half a kilometre from the site of a major slip in 2011 that closed the gorge for months.
A report published after that slip estimated the gorge closure cost the regional economy about $62,000 a day.
Mr Owen said a huge amount of work was being done to stabilise the sides of the gorge to make it more resilient, along with upgrades to the alternative routes through Saddle Road and the Pahiatua track.
Long-term viability questioned
Palmerston North Mainfreight's John Graham said his business could wear the extra cost of using the longer alternative routes for a few weeks while the gorge was closed
But he questioned the long-term viability of the Manawatu Gorge, saying the terrain meant there would always be problems.
"I'm not sure why they still think the gorge remains the best option - I know the amount of time and resource and money that goes into fixing these things and that must be stacking up somewhere for somebody."
Upgrading Pahiatua track or Saddle Road to serve as the main route between Manawatu and Hawkes Bay could be the better long-term investment, Mr Graham said.
As well as freight companies that used the route, the temporary closure was already affecting some businesses.
Bridge Cafe, on the Manawatu Gorge road, was still open yesterday but cafe manager Jack Heagney said the business was weighing up whether it would need to close while the repair work was done.
The road directly outside was still open, but traffic was being diverted before it reached the cafe, Mr Heagney said.
That was depriving the business of the hundreds of customers that usually passed through each day.
The cafe would take a big financial hit, Mr Heagney said.
"If we do end up having to close, we're going to have staff that won't have any work for two works or however long it is, suppliers and orders that we'll have to be cancelling, [and] we'll have no income obviously if we're not having customers through the door."