CBD Loop Case Close


The business case for a CBD train tunnel will be presented to the government in about 7 weeks.

ARTA and KiwiRail have been preparing the case on potential costs and economic benefits the tunnel will bring to the region.

Sources continue to indicate the chances for government approval are looking good, especially with the support of Auckland’s mayor, the ARC and others.

The concept design work to identify a required footprint,is also following the same timeframe.

The preferred option has as its three station locations:  Symonds Street / Khyber Pass Road (Newton); at Karangahape Road / Pitt Street (Karangahape Road ); and at Albert Street / Wellesley Street (Aotea).

September will be the next big month for Auckland rail with New Lynn’s completed station and transport interchange opening and the Onehunga line re-opening.




  1. Nick R says:

    This is great, but I wonder if they have even considered the other end of the tunnel, in particular whether it is actually a good idea to connect it to Britomart or not.
    Extending the tunnel all the way to Quay Park junction via a new pair of platforms alongside Britomart would allow for double the capacity increase on the rail system for far less than twice the cost.

  2. Matt L says:

    I’m really looking forward to this coming out. I really hope Steven Joyce and the government agree to fund it and if Waterview is anything to go by, hopefully they push it through to get completed faster than normal.

  3. max says:

    Nick - could that not be done later anyway, without big synergies provided by the initial construction?

    I mean the main “setting up” issues for the CBD tunnel are

    a) getting political agreement and funding (adding to the cost is going to hurt this in my opinion EVEN if the capacity boosts are even larger)

    b) setting up the qconstruction of the tunnel - with boring machines to do the work (I assume they’d do it that way, but I’m not actually sure) - but which machines probably wouldn’t be used for a tunnel under Quay Street. That would more likely be done via cut and cover.

    I think we need to keep this as simple as we can, to make it easier toget over the hurdles. I am just wary of dreaming too far, I guess.

  4. Ian says:

    I assume they would bore towards Britomart having that station as the finishing point.

  5. max says:

    I think they would bore uphill instead, making it easier to cart material out, and drain it of any water ingress. Though technology may have made those things easy enough these days that other aspects are more important in comparison.

  6. Matt L says:

    I also hope that when this study is completed that we get started on protecting the airport rail corridor.

  7. Jon C says:

    @Matt L Separately the agencies responsible for the airport road and an railway link are signing off a MOU (Memorandum of Understanding) to define and protect the route any day if it has happened already

  8. Nick R says:

    The very first part of the tunnel under the CPO will necessarily be dug out with powered hand tools as the two sections must pass under and through the foundations of the historic building above.

    The older document I have suggest they would start the bore from a large access pit dug in QEII square (i.e. big enough to lower the TBM into place), boring upwards to another pit at the Mt Eden end where the TBM would be extracted. There must be an access pit at each end unless they plan on abandoning the TBM in a side shaft.

    @Max, I think it would be more or less impossible to do at a later date as the tunnel curves/grades would be wrong for re-aligning the tunnel, plus the critical area would have been built over by the Westfield tower at that point (or rather the foundations would be in the way).

    Yes the cost is more than the rock bottom minimum required to build a tunnel, and getting anyone to spend any more than the bare minimum in NZ is always a huge hurdle. That’s about the key problem of the concept. I am also wary of dreaming too far, but I think this is just a case of making sure what we are planning on spending $1.5 billion on can actually be used to it’s full capacity. That’s not dreaming, that’s fiscal prudence. The equivalent would be building a six lane motorway but connecting it to a two lane arterial road instead of extending it 900m further to the end of another motorway.

    In regards to the second point, it would actually be easier to build the tunnel if it started under Quay St. For one you avoid the delicate (i.e. expensive) work under the CPO. You’d also have a lot more room for a proper access pit (i.e. where the new platforms would be built top down) by closing part of Quay St instead of closing QUEII square and the part of Queen St infront of the CPO.
    Yes I imagine the section from Quay Park to the new Britomart platforms would be cheaply buildable by cut and cover. This is another benefit, they could build and open that section within a few years to double the terminal capacity while the rest of tunnel is being built. Britomart is going to hit a capacity wall the second those EMUs start running, and no one is going to be happy waiting 6-7 years for the relief.

    Consider this: Britomart is currently limited to about 18 trains an hour (18 in and the same 18 back out). Because all the trains pass over the same flat junction at the head of the platforms this is pretty much the maximum possible, regardless of signalling improvements.
    They are planning on building a brand new rapid transit tunnel with new stations, to be serviced by brand new electric multiple units. A tunnel of this design would support 20 trains an hour each way with basic signalling, and 30 each way with advanced signalling. This tunnel should be adding 40-60 trains an hour capacity to the system, for a system wide total 58-78 including the existing Britomart operation.
    However because they are cutting the tunnel 900m short and bunging everything into the existing station all trains must still run over that same flat junction inside Britomart. This means the maximum the whole system could run at is only 36 trains an hour, or only 18 more than they have today.

    It gets worse though. Remember Britomart is also the terminal station, so any terminating trains must come in and out over that junction thus taking up two slots.
    Say they want to run four terminating trains each hour, those will occupy eight slots. That would leave enough slots for only 28 EMUs through the tunnel, or a total of 32 trains system wide. So effectively they would have spent $1.5 billion on a tunnel that could add 60 trains an hour capacity to the system… but in fact only adds 14 because they linked it up to the wrong place.

    The way I see it is, Auckland has a pretty good underground terminal station and it is planning on building a state of the art CBD tunnel. Bunging the two together would be an expensive way to slash the capacity of the tunnel while severely limiting the ability to terminate trains.

  9. Paul says:

    @ Nick R, I hope the planners are listening

  10. Nick R says:

    My post on Auckland Transport Blog caught the eye of Mike Lee and apparently a few others, but I can only assume their response is the same as Max’s: ‘let’s not do anything to jepordise the project or make it harder to fund’.

    I guess people are a little bewildered that this project has gained traction and looks likely to go ahead, so they are more than happy with a system that would double the existing capacity of the rail network.

    It sounds like I’m the only person suggesting that merely doubling the pretty pathetic current capacity is actually a very poor outcome for a $1.5billion spend on this piece of infrastructure.

  11. DanC says:

    Nick R, I know what you mean when you don’t want to jeopardise the project so keep it simple as planned but I do agree with you totally in what you say about your second point (if I follow you correctly in continuing the tunnel under Quay street all the way to Quay Park Junction.) Great future proofing idea. My only concern would be getting through the foundations of the HSBC building on the corner of Quay Street & Lower Albert? Would that cause a problem?

  12. Ian M says:

    I recall that Quay street would be pretty difficult to tunnel under, since it is below the water line. It would require a heavily concreted tunnel (like the concrete tank that Britomart is inside of). I do believe however that placing extra lines under Quay street is the best option tho.

  13. CB says:

    I have to ask, does anyone really, honestly believe that Stephen Joyce is going to stump up 1.5 billion on a metro rail project? I mean honestly even the 500 million for the new trains was given as a loan. Sorry but despite what he may try to present about being even handed, even looking at this optimisitcally i cannot ever see him going for it in a million years. It would be like the Greens funding the holiday highway to Wellsford. Not going to happen. I would think this will have to wait for a change of government in about 6 years or so, which would suggest this project would be about a decade from getting a start.

  14. Nick R says:

    Dan, yes you follow me right. I’m proposing they extend the tunnel under Quay St to join up with the four tracks heading out of Quay Park Junction. So instead of the four tracks Eastern and Southern lines cramming down to two into Britomart and on to the CBD tunnel, there would be two tracks heading to Britomart and a further two directly to the tunnel (i.e four into four). Britomart basically stays as it is as a terminal station, while a new pair of custom designed ‘metro’ platforms are built alongside and connected to it via the pedestrian concourse.

    Ian, the Quay St tunnel would be very similar to the existing Britomart tunnel in length, location and design (and it would likewise be below the water table). In 2000 the 506m long, two track Britomart access tunnel was built by cut and cover at a cost of $30 million. Doing the same thing under Quay St today might cost two or three times that, which is still relatively inexpensive. The actual expensive bit would be the grade separated connections to Quay Park Junction that would be needed, plus what is effectively a fourth tunnel station alongside Britomart.
    My ball park estimate is it would add around $300 million to the project, but up to maybe a third of that would be saved by avoiding the need to tunnel under the CPO or modify the platforms at Britomart. So that’s increasing the cost by about one fifth to more than double the end capacity.

    The HSBC building might be an issue, but looking at aerial photos and maps it appears there is a clear path between the two towers on the downtown mall block that would meet acceptable curves. If you look here you can see the gap the line would run through:

    CB, with enough pressure from the new council, maybe… Surely Joyce realises that over 1/3 of voters live in Auckland, with many city seats liable to swing back to Labour at the drop of a hat.

    If anyone is interested my full post on this topic can be seen here:

  15. joust says:

    @Nick R - There’s a pretty similar situation to what you’re proposing in Hong Kong where I’ve visited a couple of times “Central” is linked to “Hong Kong Station” (including the airport express) by a tunnel network, have a look online at the various maps available. Actually the tunnels have travelators and you can move through town quicker and drier than on the surface, since the tunnels are in the paid area, swiping in and out incurs a small charge on one’s Octopus card (thats been done intentionally I think).

    I’m pretty keen on your idea, though wary that extra cost might make it difficult to get across the line (no pun intended). A lot of the dialogue around the tunnel talks about “turning Britomart into a through station” and by so doing “doubling its capacity” I think everyone agrees that we do in fact have a capacity problem at Britomart. I’m concerned that the leap required to instead building a tunnel towards Britomart and _not_ connecting it’s tracks actually increasing the capacity of the system even more, and spending more money, mightn’t sound intuitive at first glance.

  16. jarbury says:

    Jon you must know something I certainly don’t if your sources are confident the government is likely to fund this project. I guess my first question would be “how?” The May 2009 Government Policy Statement specifies that no NZTA money can be used for rail capital projects, and the government’s general coffers aren’t looking too flash at the moment.

  17. ingolfson says:

    We can fund it from motorway tolls ;-)

  18. jarbury says:

    I hope ARTA’s business case specifically notes the amount of benefits to road users that it will generate. That should be the bill for NZTA.

  19. Nick R says:

    Joust, it not particularly different from the central stations of Sydney, Brisbane, Perth and Melbourne (Southern Cross).
    In each of those cities the CBD tunnels that take the electric ‘rapid transit’ trais have their own platforms alongside the terminal station that services diesel trains via their own tracks.

    To turn Britomart into a through station is going to mean every single train in the region must pass along a single two track railway. It is a bit better than the status quo, but not $1.5 billion dollars better.

  20. max says:

    Nick R, thinking some more about your proposal, I think it COULD be done (and funded, despite the additional cost), if one takes up what you said about it providing more access capacity to Britomart even without the CBD tunnel. So one could built it for - whatever it is going to be, 300-500 mil, leave a pit / construction zone at the head ready and waiting for a TBM, and then start using the rest for running more trains into Britomart in the meantime. Yeah, that could work.

  21. Nick R says:

    Thats exactly it max, it might prove to have a superior economic evaluation given the ability to stage expenditure and capacity as it is needed, plus the eventual capacity being twice as high and the other benefits like keeping a functional terminal station while running the ‘metro’ trains on custom designed platforms. It’s a little more ‘buck’ for a lot more ‘bang’.

    I think a price of $300-500 million for that first stage is probably more than double what it would actually cost. Consider the existing cut-and-cover access tunnel cost $30 million to construct, while the rest of the station (excluding the street upgrades etc) cost $204 million. A new Quay St tunnel would be about the same length and of similar design and construction, while the new station would be a lot simpler than Britomart as it would have only a single double sided platform, no need for extensive diesel ventillation and minimal above ground works.


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