This post by Nicolas Reid was originally published on Linked in. It is republished here with permission.

The idea of a bridge or tunnel between the North and South islands gets raised any time there are problems with the Cook Strait ferries, and the recent uncertainty about the ongoing plans to upgrade the boats and their terminals is no exception. At first glance this is a crazy idea, right? Well, I wanted to take a look at just how infeasible it would be to build a fixed link between the two main islands of New Zealand, and perhaps more importantly, get an idea of how much it might cost.

The first question to ask is why would we even want a fixed link between the islands, what are the reasons we might have to replace the interislander ferry? It’s important to note we’re not starting from scratch as ferries already link the islands. The benefit of a crossing doesn’t come from the act linking the two halves of New Zealand together, but how much it improves on the existing connection. So this is basically another way of asking “what are the limitations of the ferries?”

What could a Cook strait crossing do?

There are effectively three ways a fixed link across Cook Strait could improve on the ferries. These are the same three reasons that underline the case for just about any transport infrastructure project: travel time, reliability, capacity. In short, the Cook Strait ferry is fairly slow, it is subject to regular cancellations from weather and equipment failures, and these two combined with the fixed schedule of sailings limits the capacity and dependability of the link. To cover the 65km Wellington and Picton, as the crow flies, takes around four and a half hours including check in and loading time. That’s an effective speed of just 15km/h.

In comparison, a fixed crossing would theoretically be immune to weather conditions and much less susceptible to catastrophic equipment or vehicle failures, and without a fixed schedule and long turnaround times it would have far higher capacity to move vehicles, hour by hour around the clock. Perhaps most significantly the travel time would be vastly reduced, to around 40 minutes between Picton and Wellington.

Ok, so it would certainly be viable from a benefits perspective… but what about the practicality and cost side of the equation? What would the infrastructure to get a fixed link across Cook Strait actually look like? Let’s block out the main constraints and see how that shapes the design.

 The major obstacles to linking the North and South islands

The biggest problem with the strait is that it’s deep, really deep. There is a trench through the middle of the strait which drops to over 220m below sea level. The second problem is that it is wide. At the narrowest point it’s 22km across,  but that’s between the North Island and a point on Arapaoa island, one of the long and mountainous islands of the Marlborough sounds which is quite remote from any towns, roads or railways. The more practical crossing point from Cape Terawhiti on the Wellington side to Oyster Bay on the mainland is more like 30km across. The third problem with crossing the strait is that it is geographically remote and subject to some truly exceptional terrain. On either side the nearest highways and railways are some 15 to 20km away across rugged mountains, valleys and inlets, with barely a dirt road on either side.

A bridge is infeasible

The first thing we can see from this is that any crossing of the strait would have to be a tunnel, not a bridge. The crossing is just too wide, and more importantly too deep, for a bridge. It’s true there are a lot of so-called bridges that span distances across water of twenty kilometres or more, for example the bridge section of the Hong Kong-Macau link, the bridge across Qingdao bay, the crossing between Crimea and Russia or the causeway from Sadi Arabia to Bahrain. The Lake Pontchartrain bridge in Louisiana claims to be the longest bridge over water in the world, covering 38km. This seems more than enough for our purposes. However, these are perhaps more appropriately called elevated causeways or perhaps over-water viaducts rather than bridges. The difference here is that all of these superlong crossings are of relatively shallow waters, which enables them to be supported by from below on rows of piles. The have only one or two modest sections of true bridge to allow a navigation span for larger vessels. This approach is infeasible on Cook Strait however, as the supports would need to be over 200m deep to reach the seafloor, requiring hundreds of submarine structures rivalling the Skytower in height.

Currently the longest true bridges are the great suspension bridges to Shikoku Island in Japan and across the Dardanelles in Turkey. They both have a suspended span of around two kilometres between supports, a fraction of the distance over the Cook Strait trench.

I should note there are some proposals currently for floating bridges, where the suspension towers are built on top of submerged floating chambers that are anchored to the sea floor, similar to deep sea oil rigs. This has the promise of allowing bridges to be built of almost any length across great depths, however nobody has ever built one and they remain just an interesting idea.

But a tunnel is doable… for trains

So a bridge, a causeway or bridge-tunnel combo is infeasible, but surprisingly a tunnel alone isn’t. The longest underwater tunnels in the world are greater than we would need to cross the strait. For example, the Seikan Tunnel between Honshu and Hokkaido in Japan and the Channel Tunnel between England and France are both around 50km long, with underwater sections of 23km and 37km length respectively. More importantly, they are both quite deep, especially the Seikan Tunnel which dives to 240m below sea level. Furthermore, the Japanese example crosses a tectonic fault line with difficult geology, something that a Cook Strait tunnel would also need to do. In short, for thirty-five years the Japan has had an transoceanic tunnel that is longer and deeper than the one that would be required to pass under Cook Strait.

One thing to note here is that all the very long underwater tunnels are rail tunnels rather than road tunnels. This is due to the smaller cross section required for rail, the higher capacity it provides, the lower ventilation requirements and the greater safety against crashes, fires and other emergency situations. The longest subsea road tunnel in the world is the recently opened Ryfylke Tunnel in Norway. While this is also a very deep tunnel to get under a fjord, at 14km long it’s not nearly long enough. Sure it might be technically possible to build a road tunnel long enough to cross the Cook Strait, but it would be twice as long as the longest road tunnel ever built so far, and possibly the deepest. In my book that puts it into the infeasible territory, at least infeasibly risky and expensive to be considered a viable concept.

So a rail tunnel is the most feasible option then. My guestimate, without knowing much about the tunnelling geology, is that the best alignment for a Cook Strait tunnel would between Makara in the hills above Wellington to the valley behind Oyster Bay to the east of Picton. This avoids the deepest part of the trench and the worst of the landside geography, and it also avoids the power cables that run along the sea floor.

This is no mean feat, at 37km long this tunnel is quite a bit longer than just the 28km underwater section. In addition, there would need to be new rail lines extended from the end of the lines on either island. Given the mountainous terrain these rail extensions to the tunnel proper would require some heavy engineering, with numerous smaller tunnels, viaducts and a lot of cut and fill.

Overall, the total route would be about 65km between the railheads of the North and South island networks. Assuming the new crossing was designed for trains going up to 110km/h, the current upper limit for the main trunk lines, it would take about 40 minutes for a train to run between Picton and Wellington.

The new tunnel would be double tracked for capacity and resilience, and it would need to be electrified to remove the risks of diesel trains in such a long tunnel. Therefore, the project should also probably include electrification of the remaining parts of the North Island Main Trunk line, and possibly also the South Island trunk as far as Christchurch.

The road-on-rail shuttle

Even though it would be rail tunnel it would work for cars and trucks too, joining both sides of State Highway 1. This would work by using shuttle trains which road vehicles are loaded onto, which is how the Channel Tunnel operates. Therefore, tunnel would also need an extra-large loading gauge to allow trucks to be driven straight onto oversized rail carriers, at shuttle terminals either side. These would probably be at or near the current ferry terminals at Picton and Wellington, and have a pretty similar operation. The tunnel would effectively operate as a train ferry, with cars and trucks loaded on and off either side of the strait. It’s probably that a dual gauge tracks between the shuttle terminals might be required to allow for oversized shuttle trains on standard gauge as well as regular freight and passenger trains on narrow gauge to use the tunnel. Japan’s Seikan tunnel does this, mixing standard gauge passenger trains with narrow gauge freight trains.

For road transport there would still be loading and unloading time but the crossing would be about three hours faster overall, taking about 90 minutes all up. Also, the shuttle trains could be a lot more regular than the ferries, departing a couple of times an hour rather than a few times per day.

Sounds great, but how much?
Here’s the rub, planning and designing without considering cost as the primary factor is just daydreaming. A Cook Strait tunnel might be a feasible concept in a technical sense, and it might produce a whole lot of benefits over the current ferries…. But whether it’s a good idea depends on whether you can afford it in the first place, and whether the cost of gaining those benefits.

With the Seikan and Channel tunnels we have two good examples of tunnelling projects with similar size and scale that can give us an estimate of the cost involved in crossing Cook Strait. The Japanese tunnel cost ¥1.1 trillion in 1988 while the Anglo-French crossing cost £9 billion in 1994, both of which were massively over budget by the time they were finished. Converting the cost of those projects into today’s dollars gives us an indicative cost in the order of $40 to $50 billion New Zealand dollars, before inevitable delays and blowouts could stretch it far higher. At about 10% of the country’s GDP the concept is improbably expensive and would be practically impossible to fund and deliver. The cost of capital alone would push $2b a year, every year. Even if you could it’s hard to see how a such an extreme cost could stack up even with generous time savings and other benefits.

To sum up a bridge or a road tunnel across Cook Strait would be infeasible, but actually a rail tunnel carrying passenger and freight trains and shuttles for cars and trucks would be possible. At 37km it wouldn’t be the longest transport tunnel in the world, nor the deepest at 200m below sea level, but it would be close on both counts. It would deliver some pretty big time savings, with hours saved compared to the ferries, and it would provide greater capacity, flexibility and reliability to the national transport network.

However, just because it’s technically feasible and provides benefits doesn’t make it a good idea, because the cost of getting those benefits would be enormous. The travel time and resilience benefits wouldn’t come close to exceeding the $50b or so it would cost to build a Cook Strait tunnel, and the amount of international borrowing required to fund it would amount to a threat to our national sovereignty. And if we did have that sort of money to spend on transportation in the country, there are a lot of other things we should be doing first with better returns on investment.

So could we tunnel under Cook Strait? Yes, we could. Should we? No.

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  1. There are alternatives to a bridge or a tunnel to improve the connection between the North and South Islands.
    For instance, moving the South Island Port out of the Marlborough Sounds to Clifford Bay would provide a more direct route, with less constraints on ship size and speed.
    The last National led government under Key canceled the Clifford Bay project. This would have shaved two hours off inter-island rail journeys. And an hour and a half for road journeys. Yet the $525m cost and 2022 completion date was not considered worthy of government investment.
    The beehive press release had an ‘interesting’ take that the existing Picton route could cope with 30 years more service – “the investigation found Picton’s facilities are not expected to fail or become constrained due to asset age or condition, or growth in freight volumes, over the next 30 years.”
    It is also noteworthy from the Beehive press statement that both the last National government and this one consider it worthwhile to invest tens of billions of money on new motorways (RoNS 1.0 and now 2.0) from the consolidated fund (not the Land Transport Fund with its hypothecated funding from motorists). Yet National’s attitude to ports is they must be self-funding.

    1. I did investigate this a bit a few weeks ago. TBH from any official statement I could fine from Port Marlborough it seems like the “it’ll be fine for 30 years” is consistent. The upgrades funded by kiwirail were an opportunity for them, but not required.

      I’ve given up looking for consistency in transport funding in NZ. Its purely a culture war issue and has been for 20 years.

      Unfortunately the juiciest bits of the clifford bay study are still withheld. I was thinking about IOA’ing it. Commercial sensitivity has surely completely gone, 10 years on.

      1. Re: “I’ve given up looking for consistency in transport funding in NZ. Its purely a culture war issue and has been for 20 years.”
        I think the culture war preventing consistency in transport funding dates back to WW2 and perhaps for Christchurch to the 1930s (thats when NZ Rail stopped investing in passenger rail for the city and as each service came to the end of its economic life it was closed).
        National is ideologically wedded to Team Truck and Car. Labour is not exactly Team Train because their record on delivering rail projects is as bad as National. Labour lacks a clear vision and understanding of transport – thus they are easily swayed and struggle to deliver.

        1. Labour and the Coalition government before it, gave Kiwirail billions in new funding. The problem is it takes a long time to turn around an organisation in “managed decline” for 30 years. They were still making track workers redundant during the Key government despite later events proving they were vitally needed.

        2. Labour joined Team Truck and Car before the last election. They were desperate bandwagoners but still hopped onboard.

          After subsidizing fossil fuels for more than 12 months they hoped that just talking about another vehicle crossing of the Waitematā would reverse their slide in the polls. It didn’t.

          Most people (voters) drive everywhere and own, or aspire to own, a home and make a big tax-free capital gain on selling it.

          A party that threatens either tenet of the Kiwi way of life is not going to win an election.

      1. What killed them in the end was the speed restrictions in the sounds. That’s one of the strongest reasons to move away from Picton as the south island port.

    2. It’s always the case that alternative transport modes (whether it’s ferry, transit, active modes, etc.) has to either be profitable or face high levels of scrutiny whereas new roads/motorways are just handwaved away no matter the cost. Another way drivers are subsidized and treated differently from everyone else.

  2. The second National Government in 1960 canceled the previous Labour governments 100km rail corridor between Nelson and Blenheim which they had actually started. That new rail route would have provided a helpful backup inter-island freight route because it would have made a Nelson to New Plymouth coastal shipping route more viable. In the event of a large earthquake that damages Wellington’s transport links this could have been a vital contingency option.
    See the final section titled the Nelson- Blenheim line of this Wikipedia post.

    1. But the current government don’t care about rail. They want everything on trucks using second hand Roro ferries.

  3. NZs Hi Tech businesses including Computer Gaming, Health Tech, Movie making, Tourism, Education are very important to our economy. But higher taxes to pay for grandiose schemes would see more of them leave for other places such as Australia where they have been offering incentives.

  4. As Auckland proves, ferries are very effective methods of crossing bodies of water.
    The surrounding infrastructure that often delays city ferries does not help, but being able to move hundreds of people on one vehicle means ferries are only inferior to trains.
    Our entire country should operate on this logic. We are, after all, a water based group of pasifik islands, with lineal land masses that justify rail.

    Auckland’s current mayor is a fan of “heavy” rail; every person in this country knows that Auckland’s traffic is ridiculous, even more so considering it is a greater city of barely two million inhabitants.
    Buses are filling the gaps at the moment, including gaps that the powers have no intention of filling with something useful, such as light rail.
    Mass transit is a marvel of the great cities of the world; some, like London and New York, infamous; others like Budapest, ancient and modern; Bogota the best the city could do.

    At times it feels like Auckland does not even try, nor do our regions; despite knowing how amazing train travel (urban and regional) is, from their visits to foreign lands. Why can we not be a great rail and ferry nation?

    I am sure a few thousand e-bikes could fit on an interislander ferry!!!

  5. The problem with all inter-regional transport in the south island (and by extension inter-island) is the total lack of demand and population.

    SH1 north of Kaikoura carries 2500 vehicles per day. Further south there is still a decently long single lane bridge over the Hurunui river and it doesn’t even cause any real bottlenecks.

    1. NZ has 4 regions that are increasing relative to the other regions in NZ.
      Auckland, Waikato, Bay of Plenty i.e. the Golden Triangle in 2021 made up 52.1% of NZ’s economy up from 49.1% in 2001.
      Canterbury increased from 11.6 to 12.6% of NZ’s economy from 2001 to 2021.
      Canterbury is NZ’s second largest region by population numbers. Christchurch is NZ’s second largest city.
      For the last two years Canterbury has built the most houses on a per capita basis. Canterbury for decades has been NZ’s second largest house building market i.e. it is where the built environment is changing the fastest after Auckland.
      Not investing on improving the supply chain between the Golden triangle and Canterbury I think would be short sighted.
      Obviously, NZ’s population and economy cannot justify building an inter-island rail tunnel as the main article outlines but there is plenty of reason to believe smaller infrastructure upgrades would have a good cost-benefit reward.

  6. I’m not convinced that funneling everything through Wellington is a sensible option anyway given the seismic issues(by either rail or truck). Why would we not look at expanding and providing proper port services for a coastal shipping model. I imagine the bulk of the freight is between Auckland and Christchurch and my experience is that getting freight via the trucking network from Auckland to Christchurch is a minimum of 48 hours(sometimes much longer) and the price skyrockets to go across the strait. A boat trip is unlikely to be out of whack with that and would be potentially more predictable. Other than trucking companies self interest I’m not sure why we would not look at ways of avoiding wellington and the upper south Island. Lyttelton with a back up of Port Chalmers if Christchurch gets hit by another earthquake seem viable options to me.

    1. We had coastal shipping as a major transport mode. The rail ferries, from 1962 on, decimated that industry.

  7. I worry that NZ is going to sleepwalk into closing down mainline rail freight as a consequence of failing to invest in rail enabled inter-island ferry’s.
    That is the clear conclusion Richard Prebble (who is obviously not a natural pro-train lefty) outlines in his NZ Herald piece.
    “Replacing the ferries with conventional container ships is not viable. Unloading wagons makes rail uneconomic. There is no dockside capacity to load containers and passengers.
    The economic, environmental, and social impact on the South Island, on exporters, importers, industry, tourism, indeed the whole country, of not having an inter-island rail service will be profound.
    The issue is not the cost of the ferries. The cost explosion has come from the dockside improvements needed to handle an increase in freight and passengers…”

    1. I think this is where the effort needs to be made going forward. Finding space or a system where containers can just be loaded and unloaded at each end.

      1. It is my understanding the double handling and the lack of container storage facilities means the coastal container shipping option is much slower than trucks (or trains) using RoRo ferry’s. It takes too long to load. The ship has a much longer turnaround time. There are consequently fewer trips in a day. Meaning longer waiting times…

      2. Since the dominant freight pattern by rail involving the ferries is Auckland Christchurch there’s no reason you’d need to involve either Wellington, Picton or the main trunk line in any alternative containerised freight service. Just go Auckland Lyttelton for non time sensitive sea freight of containers and everything else by car/truck only ferries.

    2. “The issue is not the cost of the ferries. The cost explosion has come from the dockside improvements needed to handle an increase in freight and passengers…”

      If that’s true, then doesn’t that make it even more stupid to cancel the SHIP orders part of the project? Why not proceed with at least that, while sorting out ways of more cost-efficient land based facilities? Ships have an even longer lead time in some ways, but also have the flexibility to work with all sorts of facilities and facility locations.

      1. Exactly Damain. Nichola Willis had an immature tantrum when pulling the project back into measured achievable bounds was the sensible thing to do.

      2. Because they were only buying TWO Ferries, – to make this work you have to load the freight from the current fleet of 3 vessels onto 2,

        This requires the larger staging areas to be ready for when you switch over to the new vessels,

        Also because the new vessels are larger, you need new berths that are larger, You can get the old ferries into the new berths, but not the other way round,…

        I suspect they concluded that to run a hybrid service of new ferries partly loaded + another smaller vessel taking up the residual would have made a complex project even more difficult,

        Some of the construction requirements are pretty mind blowing,
        40 Meter concrete piles, 2.4 mitre concrete decks etc etc,

        ( now I’m not saying they arn’t needed, but the fact that they were originally costed at less than 1/4 of what the most recent estimate was, must call into question a whole lots of other assumptions in the construction project)

        1. You do realise the Wellington terminal is virtually on top of an active fault. That is where these specs are coming from. Build it properly now and no one will even remember the $3 billion when it survives the “big one” mostly intact.

    3. “There is no dockside capacity to load containers and passengers.”

      Solution, load the passengers into containers, then load the containers onto a ferry. This removes the need for expensive passenger terminal upgrades.

  8. This seems to be a regurgitated click-bait driven article. Surely there is a better use of the authors time, intelligence and captive audience than proposing this kind of hilarity.

    1. Jeez, did you read it? I think its a reasoned take on why it’s not sensible to do something else EXCEPT ferries. I think this is a reasonable time to write such an article, even moreso when the petrol heads are in charge (and have just cut the ferry project).

      1. Another one who didn’t read the last line. The post said no, don’t build one.

        Its called analysis and conclusion, Carlos. You can’t get to the latter without the former.

  9. Apparently the Valentine was a good ship but Kiwirail sold It. It wasn’t rail enabled though. So maybe Kiwirail needs to come up with a more efficient way to Road bridge their containers on and off their ferries.
    After the earthquake with the rail closed and trucking having to take a longer route some freight was diverted to Auckland Lyttleton ships. Not as fast as road or rail though. So there are options to rail enabled ferries which don’t involve long distant trucking. However there are some interesting battery powered trucks becoming available. My pick is battery swap stations on major routes. However I saw a very clever set up which using battery powered wheeled tractor units which fit between the normal diesel powered tractor unit and the trailers. Also battery powered trailers. Both these setups could be rolled out very quickly to improve fuel efficiency while still using existing diesel powered assets.

  10. I have no problem at all with fancy ferries and expensive dockside facilities. So long as the full cost of them is paid by the passengers and freight companies using them. Aircraft are better at carrying passengers and nobody in Auckland needs jam from Geraldine to be government subsidised.

    1. In case you don’t know in Auckland we have tolls on SH1. But sure add them to that shiny new Transmission Gully project too. But there’s really no reason the next ferry solution needs to include rail.

  11. Does anyone out there actually think either option will ever happen?….if so my advice is to go and have a lie down in a darkened room.

  12. The politicians can’t even agree on a 2nd Mount Victoria Tunnel!

    More recently, the New Zealand government has proposed a second tunnel. This was initially proposed as a public transport tunnel in 2022 as part of the Let’s Get Wellington Moving project. Following the 2023 general election, the new government scrapped the initiative and changed these plans into a tunnel for general traffic.


    1. Bishop and Brown are complete idiots. They listen to nobody and understand nothing. Worst. Ministers. Ever.

    2. Why is our infrastructure future still up to politicians who come and go every 3 years or so?
      Would we get more consistency from an apolitical infrastructure planning body, with a dedicated funding system?

      1. The problem is then you get unelected numpties making decisions (case study for reference: AT) and the ferries will be replaced by a proposal for an Auckland Wellington cargo bike bridge.

  13. I would be more in favor of a rail tunnel with induction capacity for any vehicle train, bus, trucks can be used hook up to rail. Many vehicles can be trained along in series together without the risk of collision between vehicles. Economic benefits should start paying back years to come, put $100b price on full scale of the project, maybe get overseas investors in the service providing, complete ownership of the infrastructure to New Zealand state

  14. Thanks Nicolas – good read.
    Im thinking we should go the other direction – 2 separate states. North Zealand and South Zealand.

    With ferry prices now priced beyond reasonable, with more increases to come – its time to recognise the South Islands independence, and cast it adrift.

    Twice as many seats at the United Nations, this has long been a desire of many on South Zealands west coast. Aucklanders are already weary when travelling in this strange and hostile land.

    Tunnel or Bridge ? – i say build a wall. A beautiful wall…. – our coalition government has recognised this and started cancelling ferries, terminals and Tarras.

    1. apart from Queenstown of course…we might need to organise a Berlin airlift situation so the fine people of the Epsom electorate can go skiiing.

  15. There’s now work being done on submarine tunnels that are located between the sea floor and surface the Norwegian’s are looking at doing it across the very deep fjords could be a solution to the huge cost ,they operate as submarines with ballast

  16. This post concludes that bridge crossing is technically not possible, and even just a rail only tunnel massively prohibitively expensive for our small economy. For both private or state investment. So no feasible alternative to shipping.
    So our current interisland freight transfer problems are only going to get worse, unless there is further investment in our inter island ferry services.
    The current route is not a monopoly, with both the government owned Interislander Line and the privately owned Strait Shipping. There is also limited, and somewhat adhoc domestic container shipping between the two islands.

    Scheduled privately owned, Roll on Roll off road vehicle services between Onehunga to Nelson and Lyttleton, and Wellington to Lyttleton, have existed in the past, but have failed.
    The Onehunga services mainly because of the challenges of operating through the Manukau harbour entrance, and the Wellington Lyttleton services because the distance was just too far for a vessel to make a return journey every 24 hours.

    The existing ports of Wellington and Picton, although well connected to road and rail are challenged by both the lack of terminal marshalling, and load transferring space, and seismic vulnerability. But they really are all we have got, so they have to made to work.
    Clifford Bay was discarded because of its extreme weather exposure, and the lack of water depth would require both a long dredged approach channel and turning baisin in conjunction with a long exposed road plus rail causeway approach to the berth.
    And nobody was prepared to fund such a speculative venture. Not the Railways, Port of Marlborough, or the Government of the day. Support was limited to “We would like it as long as somebody else pays for it”.

    The existing ships on the run, from both operators are near end of life, and are also lacking the required redundancy to operate both reliably and up to current accepted safety standards in such a challenging sea route.
    This lack of redundancy in the vital engine cooling system of the Kaitaki could have so easily lead to a major maritime tragedy.
    There may well be a similar vulnerabilities in single ring main, fuel systems serving multiple engine.

    The sea route is frequently exposed to extreme wave heights, wind conditions, and tidal flows, especially in the very confined, limited sea room areas of the Wellington Harbour entrance and Tory Channel.
    Also very significant is that these ships are required to operate days away any effective towing capacity, in the event of any incapacitation.
    The Kaitaki incident showed the extreme vulnerability to this of this route.
    This should have bought very sharp safety focus to all of those responsible for decision making, or decision procrastination, on vessel replacement.
    Nicola. lives actually depend on sound decisions and excellent equipment, on hese everyday Cook Strait transits.

    The current old dungers are simply not up to the task of safely and reliably maintaining this absolutely critical transport route.
    And replacement will take some time. Even after decisions are made.
    We are currently exposed to unacceptable vulnerabilities for our forseeable future.

    Replacing them with slightly newer vessels, but ones not specifically designed for our unique feature of Cook Strait transit is reckless.

    The harbourside land in Wellington, and to lesser extent Picton, has been shown, inside the last decade, to being vulnerable to sea level rise, flood events and seismic events.
    All events, storm surges, floods and earthquakes, that will happen again in our not too distant future.

    The land needs further preparation for these inevitabilities, whatever uses this extremly valuable land is put too. So the money very largely needs spending anyway.

    Nicola, just appointing a hand picked task group to produce yet another report is an abrogation of your very real safety and economic responsibilities.

  17. The article states ” In my book that puts…”. Can the author please provide the title of their book. Thanks.

    1. I’m still working through the final draft, but it’s called “How transit can unfuck your traffic soaked city”.

  18. Can we just lay this stupid subject to rest, for now and forever? There will NEVER be a tunnel between the two islands, and there will NEVER be a bridge. There will only be ferries or flying. End of story. I’m sick and tired of hearing halfwits talk about whether it is possible or not – just drop it. Never gonna happen. Too far, too deep, too much of an earthquake risk, but most of all, totally financially ruinous and would NEVER be loaned on.

    I mean, for God’s sake, the Channel Tunnel nearly bankrupted France and Britain, trying to bail out the Chunnel Company, which was a relatively short straight drive through very shallow, stable ground, a nice stable chalk with no earthquake fault lines, and even now with millions of passenger trips each way each year, it is not turning a profit. My uncle bought shares in EuroStar and lost all his money.

    What we need everyone to concentrate on, is how we can get some new ferries quickly, with this idiotic government in charge, without a clue in their collective heads. It is clear that we need new ferries. Do we need to wait for a storm and multiple deaths again, before BishopBrown wakes up? The ferry terminals are ancient and falling apart as well.

    1. sounds like you are in agreement with the author, and that you didnt read his conclusion.

      BishopBrown – thats excellent.

    2. zzzz hypotheticals are fun to think about, not every waking moment has to be dedicated to solving life’s problems

  19. And after watching this today with the Fat Controllrt and his sdekick Simpleton Brown we will be lucky to get anything

    Transport Minister Simeon Brown has confirmed targeted investment of more than $2 billion over the next three years for public transport projects and services, as part of the draft Government Policy Statement (GPS) on Land Transport.

    “Delivering reliable, effective, and efficient public transport is a priority for the Coalition Government. The draft GPS commits up to $2.3 billion for public transport services and $2.1 billion for public transport infrastructure over the next three years, giving Kiwis more travel choice, reducing travel times, congestion, and emissions in our major cities,” Mr Brown says.

    “In Auckland, the key focus will be completing the City Rail Link and the Eastern Busway, to support unlocking housing and economic growth. Alongside this work, planning will also be undertaken in the next three years for the delivery of the Northwest Rapid Transit Corridor and the Airport to Botany Busway.

    “In Wellington, we will continue to deliver the Lower North Island Rail Integrated Mobility (LNIRIM) project, to upgrade rail network substations, and replace rolling stock for the Wairarapa and Manawatu lines. We will also support acceleration of the North-South, East-West, and Harbour Quays’ bus corridors.

    The Government will be prioritising practical, achievable, transport projects that deliver reliability to commuters, benefit businesses, and support economic growth. Projects must also demonstrate value for money.

    “While there has been a 71 percent increase in funding for public transport over the past five years, patronage has decreased by 23 percent. This has partly been caused by COVID-19 restrictions, but numbers have not increased back to pre-COVID levels.

    “The private share of funding for public transport over the same period has also fallen from approximately 32 percent to 11 percent which is putting significant funding pressure on local councils and the NLTF.

    “I expect the NZ Transport Agency to consider different ways of funding and delivering major transport projects. This includes ‘Build, Own, Operate, Transfer’ equity finance schemes, and value capture. Ensuring local government pays their fair share, funding should also be supplemented by increased public transport fare-box recovery and third-party revenue.

    “I invite local government, the transport sector, community groups, and the wider public to have their say on the draft GPS. Projects and funding commitments will be confirmed through the National Land Transport Programme (NLTP) later this year.”

    The draft Government Policy Statement on Land Transport (GPS) document is available at

    Consultation closes on 2 April 2024.
    Mar 4, 2024 4:56 PM
    RNZ Live
    Here’s the government’s statement on the new approach to road safety:
    GPS 2024: Keeping New Zealanders safer on our roads

    The Coalition Government will keep New Zealanders safe on our roads with a stronger focus on road policing and enforcement, investment in new and safe roading infrastructure, and targeting the leading contributors to fatal crashes, Transport Minister Simeon Brown says.

    “The draft Government Policy Statement (GPS) on Land Transport outlines the Government’s change in approach to reducing deaths and serious injuries on New Zealand roads, by targeting the leading contributors to fatal crashes,” Mr Brown says.

    The GPS will guide the development of performance targets for Police set through the Road Policing Investment Programme, with enforcement targets relating to speed, alcohol breath testing, and roadside drug testing.

    “Road safety is a responsibility we all share. The Government has signalled our intention to introduce workable legislation to enable roadside drug testing, review fines for traffic offences, and review the vehicle regulatory system to better manage the safety performance of the vehicle fleet.

    “Following the release of the final GPS later this year, we will also publish new objectives for road safety which focus on safer roads, safer drivers, and safer vehicles.

    Building new and effective infrastructure, increasing maintenance outcomes, and adopting a more proactive approach to maintenance, will also help to achieve a safer and more reliable network for individuals and businesses to be able to rely upon.

    “We will invest in building 15 new Roads of National Significance across New Zealand and fix the potholes to make our roads safer. The NZ Transport Agency will also have flexibility to invest in a wide range of targeted safety interventions, on high-risk parts of the road network, where it provides strong safety outcomes and achieves value for money.

    While speed is a contributing factor to safety outcomes on our roads, the Government will not continue with the previous government’s blanket approach to reducing speed limits.

    “We will take a balanced and targeted approach to speed limit settings, ensuring economic impacts – including travel times – and the views of road users and local communities are taken into account, alongside safety.

    “I invite local government, the transport sector, community groups, and the wider public to have their say on the draft GPS. Projects and funding commitments will be confirmed through the National Land Transport Programme (NLTP) later this year.”

    1. Thanks for posting, its a rehash of whats been said, but its still contradictory.

      Cheaper petrol, and increased fairbox recovery – sounds like less PT, more single occupant vehicles, more rando DSI behaviour. New roads, cuts to walking and cycling – no lobbiest left unrewarded.

      1. Apparently he doesn’t want see any Ron’s money spent on footpaths, cycleways, bus lanes or bus stops.

  20. What about re-routing the Cook Strait power cables through a tunnel. Huge savings with far more reliable means of power transfer between the north and south Islands. Be interesting to see how much money is spent yearly on cable maintenance and cable replacement.
    Makes a case for a rail tunnel to be plausible.

    1. A tunnel is a rigid structure unable to resist tectonic shear which is a distinct possibility in Cook Strait.
      Undersea cables do have some accomodation for lateral displacement.
      Also the cables do generate heat, easily dissipated in surrounding water but another heat load to be added to the ventilation requirements if in a tunnel.
      They don’t really need maintenance, just they have a life.
      Laying an undersea cable would be massively easier then threading nearly 30 km of cable through a hole. Even worse in an otherwise occupied hole.

  21. A tunnel is a rigid structure unable to resist tectonic shear which is a distinct possibility in Cook Strait.
    Undersea cables do have some accomodation for lateral displacement.
    Also the cables do generate heat, easily dissipated in surrounding water but another heat load to be added to the ventilation requirements if in a tunnel.
    They don’t really need maintenance, just they have a life.
    Laying an undersea cable would be massively easier then threading nearly 30 km of cable through a hole. Even worse in an otherwise occupied hole.

  22. There is a way to do it.
    No digging required.
    Japan has done it.
    You use double incased cylinders
    submerged 100 metres below sea level allowing ships to pass over head
    Anchors are then attached to the tunnel cylinders & fixed to the bottom with concrete foundations.
    Cylinder buoyancy is with air inside cylinders & marine floatation devices

  23. One big challenge is that the tectonic plate in the north island is moving east and the tectonic plate in the south island is moving west to Australia. Therefore any fixed connection would eventually shear in two

    1. How about re-claiming some land across the Cook Strait to form a causeway between the Islands 🙂

  24. should have brought the two new ferries and worried about the infrastructure later , by the time the new ferries arrived the dockside problem could have been fixed . Also how do we get a price increase from 750 MILLION TO 3 BILLION ,who’s ripping who


    1. Govt preference seems to be for more second-hand ferries to replace the ones we have. If Govt can be persuaded to revisit new ferries then perhaps the idea of alternate destinations could be considered. Big question is, will they be rail-enabled or not? I suspect this govt will actively oppose this as they seem to want to undermine rail as a contributor to NZ’s transport system, and KiwiRail seems to be offering zero official push-back to this.
      By the way, your Caps Lock is stuck on.

      1. Ronnie Barker was actually a very good comedic actor, but he never shouted. That was the little one instead…

    2. Wellington to Picton Cook Strait ferry crewing like trans Tasman air services is remarkably efficient.
      Simply because a return trip can be accomplished within a single work shift.
      No need for crew accomodation or catering for the off duty hours. Come to work from home in either Wellington or Picton. Do one return trip, a crew handover and go home. No onboard crew accomodation and only limited crew catering required. Longer sea voyages are very much harder to cater for and schedule. The Wellington Lyttleton run is just a little too long to enable the same ship to depart from the same port at the same time the next night, and requires on board crew accomodation and catering.

      1. Couldn’t the more modern ships of 5-10 years from now do the run fast enough to overcome that?

        1. Interestingly ships have actually slowed down over the last two decades because the increasing price of fuel costs more then time savings can realise.
          It is easy to make them go faster but the extra energy absorbed, that is required to do so is close to a squared function.
          Spirit of Tasmania 1 29300GT built 1998 is capable of 30.8 knots but it’s 48000GT replacement under construction has less power and a design max speed of only 26knots.

  26. With the risk of seismic activity presenting the nightmarish scenario of catastrophic failure and flooding from above, you couldn’t pay me to traverse such a tunnel. That’s hard “yeah,nah!” from me.

  27. I understand the technicalities, I also know the limitations of a small economy and population. There are no current alternatives than those we have already. Air, rural roads/terminals connected by 3rd age ferries. Or 19thcentury ish narrow gauge rail.
    It is a pity but just a reality of living in a sparsely populated and isolated country,.
    Meanwhile we find it easier in our major cities to try to minimise efficiency of traffoc management with bus lanes, bike lanes and very unsmart traffic lights….. and these interminable roadworks……
    Jobs that in modern technological countries take days/ weeks seem to be weeks/months/years….. of course, for the benefit of Fulton Hogan etc

  28. Of course there should be a bridge ‘ A tunnel has no view to offer tourism and it has no option to absorb energy from the sun not to mention wind that a bridge could capture for the power grid , most people seem to be very short sighted on the universal potential that a bridge could offer if forward thinking designers and engineers factored these into this impressive world 1st project that could carry rail ,vehicles , cables and tidal flow , solar and wind generation as well as battery energy storage all combined within a breathtaking crossing for all the world to see and experience, it would easily pay for it’self within a lifetime with a competitive toll to the ferries .

    1. Actually a hydro electric dam would be even better, as by some quirk of our geography the tidal levels on both sides of Cook Strait are largely out of phase. This results in the very small tidal range at the two terminals of the power cable but the very vigorous tidal flows.
      So with wind turbines on top, wave power harvesting generators either side, and water turbines below, all interconnected on the existing DC power link, we have the single solution for a multitude of our problems.
      Building it will provide jobs for millions, and harvesting the rock for it’s construction would create abundant flat land in close proximity to Wellington.

      1. Top idea, we can try to engage the overseas contractors who will be fresh off draining the Mediterranean for the Nazis.

  29. well something has got to happen, if you have recently but the Picton terminal is a disgrace and an embarrassment to our tourism industry , defiantly not pedestrian friendly , not suited for the elderly or the disabled. As a tour guide I recently took an elderly group across the straight and was told it was suitable for them to walk but defiantly was not the case some really struggled . They also found the car deck very slippery as thats the only way to disembark the ship

  30. I rode the Hokkaido Shinkansen last year. The passenger trains are restricted to 160km/hr in the tunnel (50 minutes at that speed) because if they go any faster they will suck the doors off containers in passing freight trains.
    Bridge piers could be constructed on the Sounds and floated out and sunk and piled on location in Cook Strait. The Norwegian Ecofisk platform would be a good proof of concept. 5 to 7 suspension bridge spans in series would be required. The length would be no greater than other top ten suspension bridges but the deal breaker in Cook Strait might be wind. Decks would need to be covered and a road or rail trip would be like being in a tunnel.

  31. Invest these 50 billions in public transport in cities and intercity rail links between them on each islands instead. For inter-island transportation, I guess you will have to fly. The ATR72 of AirNZ are already pretty economical and even competitive in terms of C02 emission compared to diesel power rail and buses (around 70g of C02 per kilometre per pax). They fly too low to create contrails (like larger jets do) and don’t require a lot of infrastructure compared to long distance rail or road transportations.

  32. When I was appointed to a senior engineering position in Ministry of Works in the late 1980s I was advised by my predecessor that the question of a bridge or tunnel for Cook Strait would come up as Parliamentary Question about every 4 or 5 years and would need a cost as part of the answer. I was given the reference to a MWD file where likely costs had been worked out and recorded and these could be updated by the published cost index for the time. I was told that the magnitude of the cost would stop any more questioning about these options. No further work needed to do further research. I am sure those records are still about and could give a likely 2024 cost.

    1. If you consider that the Auckland Harbour Bridge was payed for in in 25 years with minimal cost to users compared to the toll commuters and users would be prepared to pay for a cook strait crossing today , if a joint partnership with a big company prepared make good profits from this venture teamed up with NZ then it would be more than possible ‘ especially with modern revolutionary engineering solutions for the multiple profitable uses a bridge could deliver – there is a possibility that it could be build as the worlds largest battery and nz largest electricity supplier from solar wind and tidal flow

      1. I notice all the big companies lining up to add more tunnels across the much more heavily trafficked English Channel and The Straits of Gibralter.
        As far as I know no tunnel at all could survive the shearing across the fault lines that was experienced in the nearby Kaikoura Eathquakes and on the nearby Awatere fault in 1848, and West Wairarapa Fault in 1855.

        1. What faultline is there that the proposed tunnel or bridge would cross ? none ! either side perhaps but not across so your statement is only negative lacking actual knowledge

  33. Bold vision is required. Having a conduit between the North and South Islands is not impossible.
    Rail for freight and electricity cables plus fibre. Dare I suggest, liquid transfer pipes, that could transfer fuel for limited time periods and purged between periods for safely reasons. All this is looking at a far larger picture to a solution that has to be addressed. Saying it can’t be done is not an option now as technology is proven elsewhere. User pay definitely. I like your comment. Thank-you.

  34. I believe one of the most interesting options being overlooked is changing NZ vehicle requirementa to make all cars and truck amphibious.
    Simeon can then have a motorway that drops into the harbour in Wellington and another one that rises up onto the saddle of Queen Charlotte Sound. Beautiful. Also hoverboards, there must be a hoverboard option.

  35. I think we need to look more into the option of a tunnel connecting the two islands. It is doable and we can recover costs through a toll….NZD50 each way for car and more for trucks, until paid off.

  36. I think another thing to consider, is population to justify such a large scale of infrastructure, if Wellington had a population of 5 Million and the ferry service was still the only way to cross the straight, then the amount of ferries required to meet demand would be insane. In the day way roads in Auckland will reach bus frequency, this calls for alternative methods, ie light rail. If there was a pop to demand it, then it would happen

    1. So what do we do about the outdated fleet that is causing so many issues because of ongoing breakdowns incidents and delays causing many people some serious setbacks ? waste a large amount on the same inconvenient service or have a bridge that will streamline freight and services ?

      1. “So what do we do about the outdated fleet that is causing so many issues because of ongoing breakdowns incidents and delays”

        The issue seems to be that KiwiRail assumed that the Govt/Taxpayers would just stump up the additional money that they were demanding for new ferries and fancy new terminals. The first step is to remove the existing leadership team at KiwiRail, then install a commissioner.

        The second step is to issue a worldwide RFP to provide AND to operate replacement ferries.

        1. I don’t think the ferry costs were the issue, were they? That had already gone out to tender and was awarded.

          All the noise seemed to be about the overblown onshore infrastructure.

        2. And Air NZ going by the news tonight are going to Fly an electric p;ane between Wellington and Blenheim and the Airport are building a charging station for Air NZ so why can’t the ports do it for KR with the Infrastructure , cause at the end of the day they will own not KR and if this Mob have their way the ferries could be sold of to pay for their Tax Cuts or the Tunnel under Wellington .

  37. Just get on and start building a bridge ‘ start with the piers and the roading at each end and go from there .. patch up the old boats till the job is done

    1. estimates are that Ardern govt wasted more like $150 billion and nothing good to show for it where as a bridge could likely pay for itself within a few decades using road tolls and power generation revenue if it was designed to have a solar surface ‘ tidal and wind generation and also constructed as a battery to act as a peaker plant , meaning most if not all of the funding could come from conditional investors

        1. Funnily enough people are pre-occupied with how COVID unfolded here and how the response affected them in the place they actually live, and not the experiences of other people in other places where they don’t live and don’t actually matter that much at all, other than providing a ‘could be worse’ benchmark for people who decided to wrap up their entire political identity in some sort of weird form of Covid nationalism and weren’t prepared to accept that we maybe, just maybe, got some things wrong.

        2. There is a huge difference between “Maybe we got some things wrong” and “wasted 150 billion because of a cold”.

          I was going to outline some differences but that is probably a waste of time. I think people could rather focus on the current government which, in my opinion, is trying to make life and society worse in every way they can think of.

        3. If it makes you feel any better, they have the same public service between them and actually making stuff happen that the last government had, although admittedly fewer of them.

          So I don’t know, maybe there’s times where our fundamental incapability to progress anything beyond make-work schemes for Wellington policy analysts and endless business case cycles actually works in our favour.

          It would be nice to think that at some stage a competent government and the competency to deliver key transport projects will line up but until then you probably need to be taking the bad with the good.

    2. She read a bit of History going back 100years or so where Australia locked their country down over the Spainish Flu and they had stuff all deaths where as here we had 100’s . And with her help we are still alive , you may live on the Mainland where I was stuck on an Island and we [8000plus] were double locked down so stop your bloody crying as you are still alive aren’t you .

      You have gone to Britain or Italy and DIED .

    1. Like clockwork – you express anything but absolute satisfaction about a single element of our Covid response and someone will line up an insult when you dare suggest something as controversial as actually following through with infrastructure like rapid transit in our biggest city during a climate emergency.

      1. Labour messed ALR up for sure. I am still not convinced that burying money and land for generations in multi-billion mega-highways that will only manifest car-dependency is a better alternative just because something is happening.
        And that is not even mentioning the defunding of the youth (MOE job cuts, half price fares, letting infrastructure like the ferries die) and environment (fast track for mining and motorways, DoC funding cuts, ..)

        So yeah, compared to these actions, “nothing” looks like a decent alternative!

  38. what about a privately funded project with governmental approvals, you could easily manipulate the political landscape by developing plans for a tunnel and then saying youll give the credit to which ever political party lobbys for its clearance, and to generate passive revenue during construction you start with a extension throught the wellington suburbs and a new station a little while before the tunnel entrance establishing a new community and revenue stream with competitive metro services and lowered rail prices. while also establishing alternative revenue streams such as online media services, leasable advertisements on trains and subjegation of ferry services by adding an additional ferry by the closest coastal location to the tunnels entrance, this way the project isnt subjected to political influences unless someone is an utter prick, in the short term this isnt viable as it would require someone of reasonable wealth to want to build a tunnel in the first place but, it could be complete within 30 years if a company for the sole purpose of building a cook strait tunnel was established. i like the catchy use of the name( the tunnel company)

  39. Who would choose to cross on a ferry if it cost the same to cross quickly and conveniently on a bridge ? would not the extra numbers crossing make it not only viable but profitable with solar wind and tidal generation including the same advertising program you have suggested ?

    1. The main posted article is bias against a bridge with inaccurate information because where the main section of a bridge to span for ships to pass under would not be in 200m deep water as claimed and also implied the full width of the strait which was absurd ‘ although a tunnel could accommodate well for traffic and freight it could not generate and store electricity as a bridge could or even leave tourists with as much inspiration and awe as a bridge would

      1. It’s not bias Wayne, just a realistic assessment. I have no personal interest whether a bridge is a feasible option or not.

        The fact is the strait is over 100m deep for more that three quarters of the crossing, while the central trench is over 200m deep for several kilometres.

        There’s no way you can hand wave away those conditions to say a bridge is feasible, it would be like building the Millau Viaduct ten times back to back, with most of the structure underwater.

        1. Any idea in what depth of water oil platforms work ? did I say it would be a walk in the park ? Are you suggesting that with modern engineering capabilities it is impossible ?

        2. I think you missed the point of this post. It’s not whether something is technically possible within the capabilities of engineering at any cost or risk or timeframe… it’s whether it’s at all viable, affordable or a good idea.

          To be frank, it is impractical to the point of being impossible for New Zealand to build a bridge between the islands.

        3. I think you miss the point that NZ is 2 separated islands that need a direct connection , small minded vision is the reason it hasn’t happened already , clearly NZ’s future energy demand will require increased generation and storage which is what a cleverly constructed bridge would do and add to funding this massive endeavor , Had they have started work on roading and building islands or piers back when they first debated the idea we would be a hell of a lot closer to having it completed by now – remember Labour wasted 150 billion we didn’t have with nothing good to show for it ‘ would have gone a long way to building an important profitable Asset

  40. If any tunnel I would think those prefabricated ones anchored to the sea floor would be the mostly likely these days.
    In saying that I think they should of kept the new ferry project going or at least a slightly trimmed budget version.

  41. Some tunnel projects to compare with:

    Fehmarn Belt tunnel is an under-construction immersed tunnel, which will connect the Danish island of Lolland with the German island of Fehmarn, crossing the 18-kilometre-wide Fehmarn Belt in the Baltic Sea. No. of tracks 2, No. of lanes 4. Depth including trench ~45 metres.

    The Ryfylke road Tunnel in Norway is 14.4 kilometres long, 290 m deep, and is currently the world’s longest subsea road tunnel, and the deepest tunnel of any kind.

    Norway’s world’s first floating underwater tunnel in the Bjørna fjord would consist of two 1,220m-long concrete tubes, submerged 20-30m below the surface of the Norwegian Sea. Experts say the floating tunnel concept is especially suited for deep fjords surrounded by steep mountains. The submerged tubes would be steadied either by being attached to floating pontoons on the surface of the sea or by cables attached to the sea floor.
    The tunnel is part of a series of proposed solutions for the 1110 km E39 coastal highway. It is predicted to cost $25bn.
    Currently, the drive from the southern city of Kristiansand to Trondheim in the north takes 21 hours and requires seven ferry crossings.
    [GA: not sure of the length or depth, getting diff distances from different articles and the whole route consists of different projects]

    Japan’s Seikan Tunnel is the world’s longest undersea tunnel by overall length (the Channel Tunnel, while shorter, has a longer undersea segment). Double tracked, std & narrow gauge, length 53.85 kilometres, 23.3 kilometres undersea. The track level is about 100 m below the seabed and 240 m below sea level

  42. Why not bring back the Lyttleton to Wellington ferries back in the early seventies we had them, not sure if they took railway wagons but this could be incorporated and would take all those heavy trucks off the road between Christchurch and Picton.

    1. Wellington to Lyttleton at 216nm is an awkward distance.
      It is too far for a return journey including loading times.
      So one sailing daily requires two ships. And each ship requires two crews without any allowance for time weekly time off.
      And those crews need to be accommodated and catered for.

      Wellington Picton ships can make up two return trips a day, (in the days of the Aramoana three return trips) And each return trip requires a just single crew who operate on a walk on walk off basis. So no accomodation and minimal catering.

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