Two Crown companies just spent $3 billion crossing Cook Strait separately. Why not one tunnel?

Transpower and KiwiRail are both 100% owned by the same shareholder. They didn't even talk.

  Transpower just won Commerce Commission approval for a $1.1 billion Cook Strait cable job. Three ageing cables replaced, a fourth added, capacity up from 1200 to 1400 megawatts.

  KiwiRail, through Ferry Holdings, is separately spending $1.86 billion on two new rail-enabled ferries, due in 2029.

  That's $3 billion. Two Crown companies. Same strait. Same decade. Same shareholding ministers, Finance and State-Owned Enterprises. No sign either project asked whether a shared tunnel corridor made more sense than two separate ones.

  This isn't KiwiRail's first expensive Cook Strait false start either. The previous ferry programme, iReX, burned through roughly half a billion dollars before it was cancelled in 2023. A shared strategy with Transpower, scoped years ago when both were staring down asset replacement on the same crossing, might have avoided one of those write-offs entirely.

  I've made this case since 2014, most recently in February. What's changed is the price.

New Zealand already knows what big bored tunnels cost.

Auckland's Central Interceptor, a 16.2-kilometre wastewater tunnel that went fully operational this month, cost $1.66 billion — about $102 million a kilometre.

The City Rail Link, 3.45 kilometres of twin-bore rail tunnel under the CBD, cost $5.5 billion, or roughly $1.6 billion a kilometre.

The Boring Company's Prufrock machine is doing comparable small-diameter tunnelling for $29 million a kilometre, targeting $11 million.

  Run that over the 40-kilometre Oteranga Bay to Fighting Bay route and a utility bore lands between $450 million and $1.2 billion. That's the same order of magnitude as the cable contract alone, a fraction of what Central Interceptor or CRL cost, and it does more than one job. Add a single rail track and it starts paying for the ferries too.

  The cable job is already going through fast-track consenting as a listed project. That's the exact mechanism a joint utility-and-rail corridor could have used, on the same timeline, through the same approvals. Instead the consent covers cable termination stations only.

  A rail tunnel matters because the ferries aren't just for tourists and caravans. They carry more than $15 billion of freight a year between the islands, including most of the food that crosses Cook Strait to reach South Island supermarkets and North Island tables.

Every ferry cancellation is a supply shock. A fixed rail link isn't.

  A single-track freight bore bypasses the weather entirely. No swell, no cancelled sailings, no cancelled flights, no trucks queued at Aotea Quay. That's a direct hit on the cost of getting food, livestock and freight across the strait — and on the retail price at the other end.

  A 12-foot utility bore also carries power, fibre and gas in one corridor, future-proofed rather than laid once and left. It's the pilot for whatever comes next: widen it and you have the start of the road or rail tunnel this country has ruled out as unaffordable since 1904.

  That word 'unaffordable' has done a lot of work in New Zealand for over a century. Every serious look at a Cook Strait crossing has ended the same way: a headline number gets floated, the geotechnical risk gets waved as proof it can't be done, and the idea gets shelved.

In 2018, Infrastructure NZ's own chief executive went on TVNZ and said no, and the story was dead within a week.

  But that's a psychological barrier, not an engineering one.

New Zealand has already proved the small-bore version works, just not under Cook Strait. Vector, then Mercury Energy, bored a 9-kilometre, 3-metre-diameter tunnel under central Auckland in the late 1990s to secure the CBD's power supply, at a cost of around $100 million. It's a smaller, plainer version of what this column is proposing for the strait, and it's been running under Auckland for a quarter of a century.

  A pilot bore is the smallest, simplest kind of tunnel there is. It doesn't need to solve subsea rail engineering on day one, it just needs to exist.

  Once cable, gas or freight is visibly running under Cook Strait, 'it can't be done' stops being an assumption and becomes a disproven claim. That's what actually generates the demand and the political pressure to widen a working bore into something bigger, not another feasibility study that dies in a select committee.

  The Boring Company isn't a pitch deck any more. It's running tunnels under the Las Vegas Strip, building in Nashville, and signed a contract with Dubai's roading authority this year. Governments are buying this after doing their own due diligence, not just true believers.

  None of this is a full road or rail crossing tomorrow. I ran the numbers and a such a project is feasible at $15-19 billion and could be built in time for when the new Cook Strait ferries need replacing.

  Transpower didn't need to build that first step alone. Neither did KiwiRail. They're both owned by the same Crown, answering to the same ministers, crossing the same 40 kilometres of water. They just never asked each other the question.

  Every generation since 1904 has called a Cook Strait crossing too expensive. This is the first generation for whom that might not be true — and its two state-owned companies spent $3 billion without checking.