Investment in inter-island ferries vital - Rob Rattenbury

The Interislander Cook Strait ferry Kaiarahi arriving in Wellington Harbour. Photo / Mark Mitchell

Rob Rattenbury is a retired police officer who lives in Whanganui. He has written a weekly column for the Chronicle since 2019.

The inter-island rail ferries have been a bone of contention since the Aramoana first began the service between Wellington and Picton in August 1962.

Way back then it was industrial issues that dogged the ferries. The maritime unions were powerful bodies , holding the government and the NZ Railways to account whenever it suited them.

Those days are behind us now, of course. But we are still having issues with transport across that short but very rugged strait between our main islands.

The present problems are around the ferries themselves. They are old and near the end of their operational lives. They break down often, much to the angst of the public, and the businesses which rely on the free flow of goods between both islands.

The cost of replacing the ferries with bigger, better rail-capable ferries and the infrastructure to support them is about $3 billion.

About $500 million for the ferries but the 62-year-old infrastructure at Picton and Wellington has become outdated and needs replacing. That is the bulk of the cost involved.

That idea has been stopped by the Government. Too expensive. It is a lot of money, but remember most of the cost is for infrastructure to support the ferries. Infrastructure that may last 100 years.

In the meantime the ferries still break down, run into things and generally misbehave.

Cook Strait is a dodgy bit of sea. Never to be under-estimated. Any ferry service has to be capable of dealing with the storms that beset that gap in our country. The weather is so bad at times that ferries cannot sail, as we have seen recently.

But do we need ferries? Why not a tunnel? A bridge is out of the question. The strait has a depth of 220m in places, making for very long piles. Not feasible really.

A tunnel is technically feasible though. There are big tunnels elsewhere in the world. The Channel Tunnel between England and France is 50km-long but the tunnel that most mirrors the problems we have with Cook Strait is the Seikan Tunnel between Honshu and Hokkaido in Japan.

It is 37km-long underwater, 53.8km in total. Cook Strait is only 28km underwater between possible end points at Makara and Oyster Bay with a total tunnel length of 37km.

Remember the tunnel has to sink well over 200m below the water and seabed, hence the long distance required.

The Seikan Tunnel, at 240m below sea level, also deals with a tectonic fault line as any tunnel would have to do under Cook Strait. The technology is there to do that now.

Any tunnel would need to be a rail tunnel, it is just safer apparently. But cars and trucks could be piggy-backed on special railway wagons between Wellington and Picton, a 40 minute journey.

Passenger trains would of course be fine. All trains would by driven by electricity. Imagine getting on a train in a new railway station in Whanganui’s town centre, maybe down Taupō Quay, and staying on it until you arrived in Christchurch.

It cost over $10.2b to build the Seikan Tunnel in 1988. To build such a tunnel now under Cook Strait, nearly 40 years later, is estimated at between $40b and $50b.

Sadly that is about 10% of New Zealand’s annual Gross Domestic Product. A lot of milk and wine to be sold and a lot of tourists to be attracted.

I quite like the idea of fast electric passenger and good trains travelling between Whanganui and Wellington, Hawke’s Bay and New Plymouth, always have. Maybe even into the South Island. Another pipe dream. But dreams do become reality at times.

So in light of those figures compared to the Government baulking at $3b for the recently canned project are we as a country being let down?

The reality is that any land option other than ferries between both islands is likely generations away, if ever. In the meantime we need to have a very safe and secure ferry facility able to handle projected traffic volumes for the next 100 years at least.

That $3b is a lot of money, of course it is. But can we afford not to do it? Cheaper in the long view than any tunnel.