Kaikoura MP Stuart Smith speaks to Morning Report's Susie Ferguson about his comment that State Highway 1 north of Kaikoura will re-open on December 15.

Mark it in your calendar (maybe in pencil for now). Road trip to Kaikoura: December 15.

An opening date for State Highway 1, north of Kaikoura, has been let slip at an election campaign event in Blenheim.

Kaikoura MP Stuart Smith made the seemingly off the cuff remark on Thursday, but the NZ Transport Agency would neither confirm nor deny the date.

SUPPLIED North Canterbury Transport Infrastructure Recovery alliance crews opened up a working track around Ohau Point last week.

It does tie in with their oft-repeated claim of "open by Christmas" though, and if correct, Christmas motorists will have plenty of time to make the trip between Picton and Christchurch.

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A NZTA spokesman would only say work was on track, and that more information would be revealed by the end of September to help holidaymakers plan in advance.

The alternative route through the Lewis Pass, which is about 160 kilometres longer than the journey on SH1, takes more than six hours to drive – two hours more than going down the coast.

Smith made the comment at a meet the candidates-style event, organised by the Marlborough Older Person Seminar, in Blenheim.

Re-opening the earthquake-damaged highway and the Main North Line has been a massive job, one that kicked off in earnest north of Kaikoura in February.

LAWRENCE SMITH/STUFF A slip blocks SH1 near Kaikoura following the 7.8-magnitude earthquake on November 14. (FIle photo)

Before that, helicopters trailing monsoon buckets had carried out extensive sluicing to dislodge loose rocks, but it was not until February that crews hit the ground.

Last week, a spokesman for the alliance charged with rebuilding the road and rail networks said crews north of Kaikoura had shifted more than 800,000 cubic metres of debris.

There were 10 major slips north of the coastal town that reached down to the level of the road and rail. Access around the last of these, at Ohau Point, was only established last week.

STUFF Cracks in the highway south of Clarence. (File photo)

Transport Minister Simon Bridges has repeatedly said SH1 would be re-opened by Christmas, however many questioned what exactly 'open' would look like given the devastation.

NZTA earthquake recovery manager Steve Mutton said in May that, in contrast with what happened south of Kaikoura, the highway would be fully functional.

"We know how critical this corridor is, not only for Kaikoura, but for the South Island and New Zealand, so when we open it, it will be two lanes, and with full functionality – it won't have stop-goes," he said.

ALDEN WILLIAMS/STUFF The weld representing the symbolic rejoining of the Main North Line, which opens to freight trains within weeks. (File photo)

While Smith may have just given a date for the highway, KiwiRail has been more vague about when exactly freight trains will start running again on the Main North Line.

Earlier this month, the railway line between Picton and Christchurch was rejoined in a moving, symbolic welding ceremony that came after about eight months of work.

A KiwiRail spokesman said work trains could now travel the length of the route, however a commissioning process had to be completed before freight trains could start using the line.

ROSS GIBLIN/STUFF A twisted and broken section of the Main North Line following the earthquake. (File photo)

"We are currently going through the commissioning process," he said.

"This is where we check all the systems are working as they should (including safety checks) and undertake locomotive engineer route re-certification.

"Weather has caused some delays to the commissioning process but we are confident the line will open for freight within weeks."

ALDEN WILLIAMS/STUFF Members of the KiwiRail rebuild team complete a symbolic weld to represent the joining of the line between Picton and Kaikoura in August.

KiwiRail chief executive Peter Reidy said in early August two freight trains would run each night initially, which was about 60 per cent capacity compared to pre-quake volumes.

However, this would still take some 2000 trucks a month off the alternative highway, easing pressure on a route which was never designed to be the main thoroughfare for freight.

The total cost to restore the earthquake-damaged road and rail networks around Kaikoura was between $1.1 billion and $1.33b.

ROSS GIBLIN/STUFF NCTIR crews have shifted more than 800,000 cubic metres of debris north of Kaikoura that came down during the earthquake and ensuing rain events. (File photo)

Bridges had also announced $231 million of improvements for the highway, including a 11km combined walking and cycling trail between Mangamaunu and Okiwi Bay.

* Audio courtesy of Radio NZ