NZ earthquake: The true cost revealed

It could be years until State Highway 1 is properly repaired (Newshub)
It could be years until State Highway 1 is properly repaired (Newshub)

One of the world's leading civil engineers believes it could be years before State Highway 1 and the adjacent rail line along the South Island's east coast can be repaired following Monday's earthquakes.

Australian-based disaster management expert Paul Seinfort, who worked out of Christchurch and Japan following the 2011 earthquakes, says the repairs will be lengthy and cost hundreds of millions of dollars.

"It's going to take more time than people realise, and politically, that's tough for the politicians to handle," Dr Seinfort told Newshub.

"People want to be told that it's going to happen very quickly, but just look at Christchurch. It's still being rebuilt and it's still got a long way to go. I'm not saying these roads (SH1) will take anywhere near that long but it's going to take months, and probably years.

"It could be months before the work can even start because of all the pre-work."

Dr Seinfort says each phase of the initial response, recovery, and reconstruction process will need considerable thought and planning.

"The first thing is to do soil assessment, testing and general geological work, and then do the design for the retention. The rubble then needs to be carefully cleared out before you can even put through a temporary road."

Dr Seinfort says the most expensive exercise will be rebuilding the decades-old rail tunnels.

"Tunnelling can be up to $100 million a kilometer, and it could be more costly than that because you've got to do a reconsolidation, and then you've also got to do retention. This will take years."

A temporary route through Lewis Pass will likely be needed to freight goods from Picton to Christchurch, while another option is ferrying goods direct to Lyttelton Harbour by sea.

Kaikoura itself faces a far more uncertain future. The tourist town, famous for its award-winning whale watching industry, could suffer greatly in the months and years to come if the roads around can't be opened.