Coastal shipping is the only way to make up for delayed freight after slips blocked direct road and rail travel between Picton to Christchurch, Mainfreight boss Don Braid says.
With State Highway 1 both north and south of Kaikōura out of action for 15 months to two years, freight using Cook Strait ferries was being forced to go by truck along State Highway 7 across the Lewis Pass towards the West Coast.
Traffic on the inland route (State Highways 1, 7, 65, 6 and 63), currently the only route in to Kaikōura, has more than tripled in places, though it is not suitable .
The head of the transport giant, Don Braid said that road was becoming heavily overloaded.
"I think it's quite serious. You know, the supply lines into Christchurch and further south are tenuous right now, and I think we certainly need a solution.
Mr Braid said the Lewis Pass route was not built to handle the amount of traffic which was building up along it.
"Normally there is 40 trucks a day. I think at the moment it's up to 700 and next week would be the biggest straight week of the year and it's likely to get up over 1000 trucks, I think, a day."
"It's not built for that number of trucks. The congestion both down and back is a problem, but the state of the road is not good either."
NZTA said yesterday that engineers and road managers were looking at ways to improve the Lewis Pass route so it could cope with the extra traffic until SH1 re-opened.
But with 28 moderate to major slips and four damaged bridges between Cheviot and Ward, that will take months - if not longer.
Dedicated coastal shipping between Auckland and Christchurch would be the best way to compensate, Mr Braid said.
He said there was only one dedicated coastal shipper - Pacifica, which operates two ships - and Mainfreight believed another ship was needed.
A single KiwiRail-chartered ship, supported by international flag vessels, would be the best option, he said.
"With the support of companies like ourselves then the cost makes it viable.
"We just don't need to be moving that much by road on State Highway 7 and we've got to find what that alternative is and it's coastal shipping."
Cook Strait ferries going further south to Christchurch would not be a solution because they were not suitable for the journey, he said.