The new route decided for Manawatū Gorge road will take six years and up to $560 million to complete.
The road along State Highway 3 has been closed since last April by slips in the gorge.
Road planners have picked the third of four options, running south of Saddle Road from near the Te Apiti carpark western entry of the Gorge and emerging at Woodville.
Road Transport forum chief Executive Ken Shirley says on key counts, including avoiding quake fault lines where possible, the chosen option was the best one.
"The road freight sector's preferred option was always option three," he said.
"It is the most direct route and it also has the better grades."
Trucker Alan Castles of Dannevirke Carriers said 2024 would be a long time to have to wait for the road to be ready.
"A helluva long way out for us, and a lot will happen between there and then, so we've just got to knuckle down," he said.
The Transport agency said the option it had picked, slated to cost between $390 million to $560 million, was the safest and most resilient route.
"Everybody understands just how important a replacement for the Gorge is. It will re-establish a key strategic transport and freight link that supports the needs of the people and economies of Central New Zealand," Transport Agency regional relationships director Emma Speight said.
At 12.4km long the expected drive time is 13 minutes, some 3.7 minutes shorter than the old Manawatū Gorge route.
"It's got a maximum gradient of 8 percent which is important for the freight industry, and the resilience of the route is much better because of where the fault-lines are in the region," Ms Speight said.
A full business case is now being worked on, which will narrow down the cost more. Design work will then take two years, and four years for construction.
"This option has a very good construction timeline, so we are going to work as hard as we can to ensure we can build it in the shortest time possible and in the meantime we'll continue to work really hard on those alternative routes of the Saddle Road and Pahiatua Track to ensure that people are able to still move freight and get between the different sides of the island," Ms Speight said.
The plan has been met with cautious optimism by the region's mayors.
Palmerston North's mayor Grant Smith said that it was "a game-changer" because a like-for-like road would have had significant drawbacks.
"It would've just replaced the point A to point B with Ashurst with no connection really with the heavy traffic out of the city of Palmerston North linking in distribution hubs and logistic hubs."
Tararua district mayor Tracey Collis said locals, who had been forced to use the Saddle Road or Paihiatua Track, would be pleased the end was in sight.
"We've got the shorter build time, we've got still a very direct route and we've got a detailed business case being undertaken on the regional freight ring, so I think it's actually a win-win-win," she said.
The three regional councils would try to help speed up the build, for instance by working to make enough skilled workers available, Ms Collis said.
Some locals preferred the fourth option south of the gorge, but that would have taken longer to build.
The new route is specifically designed to avoid fault lines, so it will be less vulnerable to earthquakes and natural disasters.
However, about six farms will have to give up land under the Public Works Act.
Ms Speight conceded that could cause some friction.
"Any process where putting a road through privately owned land if people are affected by it, they need some time to consider the impact it's going to have and how they want to respond to that."
Local farmer Stuart Bolton, whose family's properties will be affected, said he was not overly worried about his own farm but it could be difficult for his elderly father to accept.
"For someone his age to comprehend a highway going through his property is mind-boggling to say the least, so there are issues there that we need to manage."
Federated Farmers president Richard Morrison said it could be tough on individuals but it would be good for the region.
"The whole regional economy needs an efficient way through the gorge.
"You know, we've seen the disruptions through that road in the last few years, but to keep the country moving and to keep produce going back and forth we need the good options and there'll be probably winners and losers depending on what course of action is chosen."
As part of a new freight ring road, a second bridge will be built across the Manawatū River.
A second bridge over the Manawatū River would help link key industrial areas and remove heavy trucks from Palmerston North's city centre, the Transport Agency said.
"It would connect key freight hubs and bring significant improvements to freight and passenger vehicle movements through the Central North Island hub of Manawatū, improving travel times and lowering costs," Horizons Regional Council chair Bruce Gordon said.
The freight ring road is still be consulted on.