An article in the NZ Herald today explores the possibility of looking at possibly up to four stations being constructed on the CBD Rail Tunnel – rather than the current proposal for two (well, really three if you count the relocated Mt Eden station). This idea has been floated by Mike Lee, the Chairman of the ARC and most probably Auckland’s biggest public transport advocate – so it’s something worth looking into a bit more. Here’s the relevant extract from the article:

Auckland Regional Council chairman Mike Lee has asked officials to consider adding more underground stations to a proposed $1 billion to $1.5 billion rail tunnel below the central business district.

He wants a $5 million study commissioned by KiwiRail and his council’s transport authority subsidiary to consider doubling to four the number of stations proposed for a 3.4km route between Britomart and Mt Eden via Albert St.

Until now, only two stations in the vicinities of Aotea Square and Karangahape Rd have been suggested for the study’s purposes of recommending a preferred route.

But Mr Lee has baulked at a suggestion by council member Joel Cayford, a former regional transport committee chairman, that the study also consider future underground connections in other directions from the tunnel.

“Let’s not get too complicated – this is about the CBD tunnel and we have to justify it to the Minister [of Transport, Steven Joyce] and as soon as possible,” Mr Lee told Dr Cayford and other councillors…

…Mr Lee, despite his cautionary advice to Dr Cayford, nominated Wyndham and Victoria Sts as possible sites for two extra stations to cater for a growing inner-city population of apartment dwellers.

Now let’s get a couple of things out of the way to start with. Firstly, it’s fantastic that this project is continuing to get more and more publicity. There now really seems to be some real momentum behind the CBD Rail Tunnel, and I am very much looking forward to the outcome of this research study into the tunnel. Secondly, I agree with Mike Lee that this is not the time to be looking at alternative alignments. The one chosen for further research is very similar to alignments that have been looked at over the past 80 years and it is one that makes a lot of sense. If there ends up being nasty unforeseen problems with this option, then I think we should look at alternatives – but for now I am really of the opinion that as much effort as possible needs to be put towards promoting this project.

So if we turn to the number of stations, as you can see on the hastily drawn map of the route I have done below, there will definitely be two new stations – Midtown and K Road – while the current Mt Eden station may well be shifted to the southern end of the rail tunnel so that it can provide better access to Eden Terrace.

While I agree with Mike Lee on most transport related matters, I must say that on this occasion I don’t actually think there is much point in building more than two stations. I have three main reasons for this opinion:

  1. Underground stations are really really expensive. Two more stations could potentially add up to $200-300 million to the cost of this project – pushing it out from $1.5 billion approximately to around $1.8 billion. I’d hate to see that being the difference between the project going ahead and not going ahead.
  2. The grades of the tunnel are already going to be pushing what is possible. The tracks aside platforms need to be pretty flat, which means that with four sections of flat track rather than two sections, the remaining area is going to need to be steeper to compensate. This might make the project technically unviable.
  3. The benefits of additional stations are relatively minor.

Working through these three points, I must admit the first one is largely guesswork. However, I do know that underground train stations are enormously expensive and difficult to build. Throughout the lower part of the CBD the train line will be travelling underneath Albert Street, which means digging down to build a large area for an underground station is going to be a challenging and very expensive job. This project is already expensive enough, and will most likely already struggle to get enough funding – so I see little point in raising the cost of it even further unless the benefits gained are particularly massive.

In terms of the grade of the tunnel, if we take the figure of the article above, the tunnel will be approximately 3.4 km long. The tracks at Britomart are a few metres below sea level at the moment, while the current Western Line at Mt Eden station is approximately 72 metres above sea level. Generally it is considered that a railway track should have a grade of no steeper than “1 in 50” (one metre up or down for every 50 metres across) for extended lengths, although there are some places where this is exceeded. Getting trains up around 75 metres at a 1 in 50 grade would take around 3.75 kilometres of track – which we don’t actually have here. Further complicating matters is that at stations you cannot really have a sloping track as it can be difficult for trains to get started and go uphill immediately – so we can effectively remove a couple of hundred metres from the total distance for each station that is included. Doubling the number of stations on the line would double the length of track that couldn’t be rising, which therefore increases the steepness of the track elsewhere in the tunnel. If we had four stations, each with say 200m of flat track set aside for station platforms and “vertical curves” (where a flat bit of track slowly becomes a rising or falling bit of track) that would effectively remove 800m of length from the tunnel, which is already arguably a bit too short for the climb it has to do. This might be the final killer blow for this idea, as it could make the whole project practically impossible.

The third point, is questioning whether we really need any more stations than the two currently proposed. More stations will slow down the trip, they will be expensive to build and so forth. All in all, for there to be more stations they need to be highly justified. To get some idea of how well the current station locations “cover” the CBD, I have used the trusty Google Earth to measure the distances between the stations on the northern side of where the railway line would go underneath the Southern Motorway. These are as follows:

  • Karangahape Road station to Midtown Station: ~970m
  • Midtown Station to Britomart Station: ~770m

Generally it is considered that 400m takes about 5 minutes to walk. So this means that even if you’re bang in the middle between Midtown Station and Karangahape Road station (which would be around the bottom end of Vincent street) you would still have not much more than a 5 minute walk to either of those two stations. If you were bang in the middle of Midtown and Britomart stations (around the intersection of Wyndham Street and Albert Street) you would have barely a 350m walk to either station – taking less than five minutes. So I really can’t see either of those situations being poor enough to justify the huge extra cost in having additional underground stations.

Overall, I don’t really think it’s worth pursuing adding any additional stations to this proposed project. I think it would work just fine with the suggested two main stations.

Share this


  1. I completely and utterly agree…

    You need to stop doing such excellent pieces of analysis Josh or nobody but Liberty will post..!

  2. It would be interesting to look at a cross section of the route, especially where the alignment would cross the motorway. Some thoughts:
    Would the track be high enough to span the motorway on a viaduct, yet low enough to emerge from a tunnel in the embankments at either side?
    Or would the rail tunnel go completely below the motorway, thus implying a deep underground station at Mt Eden, and the track joining the western line at some other point?
    Would there have to be some nasty stretches of cut & cover as the track approaches the junction with the western line and their relative levels merge?

    I imagine this portion of the route could be tricky.
    Great post & blog by the way.

  3. Yes agree four stations is overkill. Let’s stick with the original plan, the last thing we need is needlesly inflate the cost of this project by adding another station.

  4. In Paris some metro lines cross the Seine river overground (on a bridge) and go back into a tunnel at either embankment. Maybe a similar set up to cross the motorway rather than underneath it would have to be divised, because otherwise K Rd station will have to be 50-60 meters underground.

  5. Too deep and I think you could kill the K Rd station. A bridge across the gully seems pretty impossible though. Conundrum….

  6. There is no choice about whether the tracks go under or over the motorway. They simply have to go under it as otherwise the tunnel will be far too steep between Britomart and K Road. So the station has to be deep.

  7. Raffe/Uroskin, The tunnel long section passes well below the CMJ gully, like about 20m under. The constraint here is not passing the rail line under the motorway, but the climb from Britomart underground station (below sea level) to the western line at Mt Eden (72 odd metres above sea level). Heavy rail can only climb about four metres height for every 100m long at absolute maximum, ideally less than 3 in 100. Effectively the CBD tunnel will be a 3.5km long incline at maximum steepness, save for the flat sections where the station platforms are.

    As you can see above K Rd is only about 2/3 of the way between Britomart and the western line, so at that point a good 1/3 of the climbing is yet to be done.

    Basically the depth at K Road has nothing to do with the need to get under the motorway. The station will be about 35m underground simply because the maximum-steepness tunnel will still be 35m below the surface at that particular point.

    As it is I believe the tunnel is too steep to handle the kind of headways it could. I think the answer is to firstly connect the tunnel to Quay Park Junction (with new platforms under Quay st alongside Britomart, and an extended concourse), not directly to the existing platforms at Britmart. This means that the tunnel could not only start less deep, but also have a greater length in which to climb, so it would be less steep overall.

    Secondly, they should omit the underground station at Eden Terrace. Not only would this save a few hundred million bucks, it would eliminate one of the three flat sections required. This would also make the tunnel less steep overall. In place of this or the existing Mt Eden station (which would be obliterated by the new tunnel junction), they should build two new stations.

    One would be Mt Eden station relocated to the eastern side of Mt Eden Rd, on the straight flat bit of track just by the Horse and Trap Pub. This would maintain a station in the area and provide interconnection with Mt Eden Rd bus services. Moving the station to the west a bit would also be good now that Boston Rd has been moved a few hundred metres westward. This would be the Mt Eden area station for services operating between the top of the tunnel and south via Newmarket.

    The second would be a new station on the straight, flat section of track where the western line passes under Dominion Rd. This would provide a station for walk-ups in that area but would gain the most benefit as a transfer point between what will be effectively the Dominion Rd busway and the rail network. This would be the station for services operating between the tunnel and the west.

    With both of these in place, there would still be the same number of stations on each line. The downside would be an extra stop for any service going direct from the west to Newmarket, and anyone wanting to transfer between the two other patterns would have to go as far as K Rd to make the connection.

  8. I thought light rail could also operate on heavy rail lines? Is this true, and if so why not have light rail run through the tunnel only, and have this as the main passanger transport? Don’t know the full aspec’s of light rail vs heavy rail etc but would this be possible or will it not solve the grading problem. However two stations would still be enough, don’t need anymore.

  9. You can have special light rail tram-trains that could run on heavy rail lines, but there would be more expensive than regular EMU’s and have maybe one-half to one-third of the carrying capacity because they are smaller. They also have very different platform heights, meaning you could only run tram-trains or EMU trains on the network but not both.

    The answer is just to get the CBD tunnel working right for EMU’s on the existing system (its certainly not impossible), rather than convert the whole system to less effective tram-trains to make the tunnel easier.

  10. Scrap both KRD station and Mt Eden Station and have a TRAM simply run up and down Queen St.
    The majority CBD stations are britomart and Aotea anyway.
    Then…Start the tunneling from the western line about halfway between kingsland and
    (current) mt eden and then the steepness isn’t too bad and only One staion(Aotea/midtown)
    on the route.

    Queen St is wide enuff for trams and quiet during the day.

  11. I suppose the answer will have to be two sets of really long escalators, like at Melbourne’s Parliament Station. You’d want at least three, with two or more going in the peak direction. They work fine there, even if being so far underground takes getting used to.

  12. Inner city suburbs like in melbourne are served by trams
    not heavy rail…my point is Mt Eden/parnell/grey lynn
    could be served by a spider tram system..

    If this is too much at least put a tram on the following:

    Britomart-Aotea-krd-mt eden-kingsland(eden park!)

    Thus then no rail station for krd or mt eden.

    this would seriously speed up western suburbs commuters into the city.

    also after eden park match…two forms of rail into town.

  13. K Rd would be a few metres less deep than the lower platforms at Parliament, and a lot less deep than many metro stations in the world. I don’t think there is any problem with the depth at all, it’s not unusual.

    I would love it if K Rd was built with a tall vaulted ceiling to compensate for the depth, rather than a nasty little hole in the ground.
    Perhaps it could have a few entrances leading to a concourse level just below street level, then a main set of 3 or 4 escalators in a tube with a drop of about 25 metres to a mezannine level looking out over the platforms and tracks, about five or six metres below. So in the station itself the ceiling is maybe ten metres tall.

  14. Thanks for your explanation Nick, I think I had assumed a constant gradient from Britomart to Mt Eden, and my unfamiliarity with the topography meant I assumed the track would be much nearer to the surface (or above it) at the CMJ.

    A precedent for a grand K Rd station would be Canada Water, on the Jubilee Line Extension in London. The station is a wide circular shaft 25m in diameter with lets daylight filter down, with escalators cutting chords around the circumference of the shaft to provide access to the platforms. Whether the CBD rail loop budget would extend to such quality architecture is another matter…..

  15. It is a complex issue this CBD Rail Tunnel, and it will be a pretty amazing engineering feat if/when it is built. Jonathon, interesting that you mention Melbourne as they DO have an inner-city rail loop that circles around their CBD. It’s not a choice between buses, trams or trains – I think we need all three of these transport options – used along the corridors that suit them best.

    We do desperately need the CBD Rail tunnel, we also probably need trams along particularly suitable transport corridors (Dominion Road, Tamaki Drive and perhaps the Link bus route to start with), and we also need to continue to improve and develop our bus system.

    Raffe – that Canada Water station sounds fantastic. I too hope that there is some money in the project to ensure the stations are nicely designed. Getting natural light down into such a deep station at K Road would be pretty awesome.

  16. Ok fair enuff, if Krd can be turned into a deep station
    *not too far down* then have it. But then i think Mt eden
    could still be scrapped/and or moved further west…75metres is a big climb for a train on short distance.

  17. I would certainly lower the Western Line a bit through Mt Eden so that the tunnel’s grade is eased. A shorter version of the trench being built at New Lynn would do the trick.

  18. That is a great idea, why didn’t I think of that and more importantly have the feasibility study engineers..? An e-mail to them maybe..?

  19. The previous study into this project highlighted that as one way to reduce the tunnel’s grade, so I am sure it is being looked into. I just hope the new study does not come back with a cost of $2.5 billion or something like that.

  20. IIRC there was the possibility of having a trench basically from Dominion Rd to Mt Eden Rd. However if I remember right all this allowed was the grade to be eased from 3.5% to 3%, which is the difference between needing custom built trains and the absolute maximum that normal trains could handle day to day.

    I hope the electrification tender specifies a high level of power and traction regardless, Auckland is one hilly place.

  21. A trench makes a lot of sense – especially as I think that Mt Eden station is basically at the very peak of the Western Line’s elevation. Slicing across the top of that “vertical curve” would reduce the gradient for all trains on the Western Line too, and if it was covered up could create some good development sites in the Eden Terrace area.

  22. Instead of a trench why not just leave that part of the western line as it is, and start the tunnel ramps further along the line each way.

    You could have a single track ramp either side of the mainline at the two ends, this would result in a flying junction underneath Eden terrace somewhere, rather than a flat junction where the existing station is.

    See an example from Melbourne, these two ramps down to/from the city loop start a good kilometre back from the MCG proper:,144.982254&spn=0.001074,0.002784&t=k&z=19&msid=101291069583876254503.0004768f811186193c95d

    However some kind of trench on the eastern approach would allow for and underpass of Normanby Rd, possibly the same to the west with George St also if they were to lower the track back that far.

  23. Presumably the location of the ramps would need to be twice as wide as current to fit in the two main lines plus the two exit ramps, but apart from those two stretches of a few hundred metres the rest would be underground (or at least built over again once they were built).

    Really, if they were planning on a new underground eden terrace station, then the western approach tunnel could start just after Kingsland, and the eastern one just after Grafton. I wonder if the grade benefits of spliting the junction into a big underground ‘Y’ would outweight the extra costs.

    The simcity fan in me says raze the lot, build a massive underground junction, the re-develop the whole area intensively 😉

  24. the problem in auckland is not the amount of stations its the crazy price we are expected to pay.. to train from pukekohe to britomat station costs $10 EACH WAY. for two of us thats $40 A DAY. considering it costs $8 of petrol to drive the car, its just not financially sensible to use the train.

  25. Pukekohe to Britomart is $9.10, or $8.15 if you buy in books of ten. You also have the option of a $10 day pass that is valid after 9am during the week and all weekend, if that suits of course.

    Train travel isn’t super cheap, but it isn’t particularly bad either. Certainly if you already own a car and there are several people going at the same time then the marginal cost of gas divided between you is going to be way cheaper than a train fare each.

    However if you consider the other running and ownership costs of cars then it can work out cheaper…. especially if using the train to get to work lets you get rid of one car. While just about everyone will want access to a car there are plenty of housholds that have a second (or third or fourth) car that basically exists just to get one person to work and back. If a houshold can get rid of an extra car then they can save $3,000 to $5,000 a year in gas, maintenance, rego and insurance, plus they get back whatever the car sells for and of course they don’t need to replace it in the future. In the right circumstances the savings are several times what a train or bus pass would cost each year.

    Another thing to consider is how you value your time. When driving a car all you can do is basically listen to the radio or perhaps make a handsfree phone call, even if you are a passenger it is hard to do much more than sit there. On the train however it is much easier to read, write, make phone calls, read the papers or use a laptop.

    It’s hard to put a dollar value on commuter time, but for a business person or student who can get work done during their commute that could add an hour or two of productivity each day.

  26. Why do we need this hair brained rail line any way, it will be a Bordon on the Rate and tax payers for ever, it is undo able, it would have to start from well below sea level at the bottom of town to miss the foundations of buildings, the incline will be too steep to get to the Western Line at Mt Eden, and don’t forget it has to surface to connect, don’t be too proud to turn the clock back,and put some Tram Lines on the surface, they can negotiate both Queen St and Parnell Rise, many over seas cities work quite well with Trams and they are cheaper.

    1. Have you read the business case? You’ll find all your answers there.

      In short:

      1) The incline is steep, but apparently not too steep
      2) Tram lines can’t offer the capacity that this tunnel offers
      3) The business case looks at other options – most particularly bus lanes – but that isn’t really feasible and doesn’t solve rail capacity problems.

      I could keep going, but seriously read the business case. Even just the executive summary.

    2. Funny how all those transport experts and engineers not only think it’s doable they also think it’s the only feasible option and will provide a pretty handsome return the investment in it. But then again, they clearly didn’t ask you and must have forgotten that the tunnel would need to connect into the existing rail lines at surface level…

  27. Due the news that the Aotea Station (Midtown) is going to bigger than Britomart, I think we should forget about a K Road Station & just build a big Aotea Station.

    1. I disagree. They service very different parts of the central city. If any station is to be knocked out it’s likely to be Newton: though that would be a big shame as a station in the proposed location would have huge benefits for encouraging development.

      1. So what would be the distance in between the stations on the network. After seeing how close together the Western Line Stations are(up to about Mt Albert to Kingsland) & how close Manurewa Station & Te Mahia Station are, I’ve been having doubts with having 3 stations in the Tunnel. I know it’s a major transport project for not only Auckland but New Zealand, but yeah.

        1. Kingsland to Symonds St would be about 1.6km, about 700m to K Rd, 1.1 to Midtown and 900m to Britomart. By removing one station it would only save about 1 minute and I think in this case the patronage gained by having it would easily outweigh the time lost by stopping there. As part of the tunnel business case they also investigated areas for development and there were quite a few around the station so there is plenty of potential.

        2. In central cities extra stations can make good sense because the catchments served are much denser. The real question is whether we can afford all the stations – I certainly hope so, but they’re a pretty expensive part of the project.

          From memory, all three underground stations are more than $100 million each to construct.

        3. Impressive. I’ve always misunderstood the Tunnel, but after seeing the oppourtunities it will bring for Auckland, I was like “HURRY UP JOYCE!, TIME FOR THE RoNS!!!, Rail of National Significance!” :D.

          Also another thing. I took trains along the Eastern, Southern & Western lines (in that order) & was amazed at how long the platforms at all the stations are. I was also amazed at how small the shelters looked compared to the platforms. Does anyone know how long the new 3 Car EMU’s will be?, also are there any plans to extend the shelters further along the platform?.

        4. I think EMU cars will be ~24m long, so three of them will be ~72m, six will be ~144m, our current carriages are ~20m. Note the tenders have yet to be finalized, so the spec could still change.

        5. interesting point about the shelters though. Baldwin looks all very nice on a sunny day, but on a windy/rainy day catching the train could be very miserable. Having longer shelters would be much better, also more shelters on access points and overbridges etc.
          Maybe more shelters will happen as patronage increases.

  28. Newton is essential for interchanging with buses (light rail maybe) from Dominion, Sandringham, Mt Eden Roads.
    Also will provide interchange with buses for older people who dont wish to walk to uni area.
    Offers best chance of redevelopment and ability to profit from betterment.
    I hope a whole lot of rubbish properties can be acquired for ‘construction’ and then sold off as development sites once the tunnel is built.
    I think this could be a really cool area, with the old shop frontages giving character, and the neglected Basque Road reserve being a focal point.

  29. There is a huge amount of development potential in the Newton area, in terms of future city growth Newton should be ranked No.1 priority.
    As it is they could build three or four skyscrapers without acquiring any property, there are several empty lots used for carparking.

Leave a Reply

Your email address will not be published. Required fields are marked *