Bridge or Tunnel Report Close


A bridge or a tunnel? We will know this month more of the thinking.
NZTA has been preparing a business case for the additional Waitemata Harbour crossing and it should be out by March 31.
The study investigates both options for an additional crossing but makes no preference. Given the size and impact of such a project, NZTA says it believes a preference is one that should be decided by the people of Auckland.

A tunnel was identified earlier but the government has asked for a ‘rigorous examination’ of costs and economic impacts of both a tunnel and bridge option.
For months, the word inside the Beehive has been that Government ministers involved have ben favouring another bridge, hence forcing officials to revisit an issue that has been well canvassed and agreed upon.

Another bridge or a tunnel?

The group pushing for the iconic Anzac bridge instead of a tunnel were claiming in the early days that was also the vibe they were picking up.

A concept of the Anzac bridge

Transport Minister Steven Joyce has not publicly revealed his preference but said building a third harbour crossing is a key transport priority for the government in its 20-year infrastructure plan and as for timing: “It is my current expectation that construction will largely occur in the second half of the twenty year period.”
It’s my expectation that the third harbour crossing will increase the number of lanes across the harbour and also allow for public transport corridors and walking and cycling.”
Back in December 2009, NZTA said a tunnel was still its preferred option and that a tunnel was estimated to be around $600m cheaper than a bridge, which was estimated to be around $3b. The agency emphasised it was difficult to be precise at this stage.
It did say an advantage with a tunnel is that parts could be built separately at different times, such as a road then rail tunnel whereas a bridge needed to have all components in the one structure. The estimates were based on NZTA’s preferred Tank Farm, Esmonde Rd alignment.
It seems extraordinary - and very pre-supercity- that we should still be having this debate.

The preferred option in the old Auckland regime

The Tank Farm to Esmonde Rd tunnel was the preferred option for a new harbour crossing after officials in the old era considered an extraordinary number of options – 159 of them. Those options included tunnel’s bridges, sky cabs, monotrail or using ferries.
In a rare agreement, NZTA (formerly Transit NZ), Auckland City Council, North Shore City Council, ARC and ARTA wanted road and rail tunnels to carry SH1. But the tunnels would not all be built at once, especially as the CBD rail tunnel and rail on the North Shore are yet to get a Government buy-in.
Their preferred option was four driven tunnels – two each for road and rail.
13 months ago, NZTA lodged notices of requirement lodged today,with the Auckland and North Shore councils for the favoured tunnel route, are to preserve the option of using tunnels for an additional crossing and to protect the route for the crossing.
If that route was not protected then, construction of the new crossing could be compromised by development of Wynyard Quarter at the southern end of the proposed new crossing.
An engineering report around that time counted down how few years are left with the current bridge: 10 to 20 under the current regime; 20-40 if restrictions are placed on early morning heavy vehicles and more than 30 if this is accompanied by some form of temperature control.

Retiring North Shore MP Wayne Mapp said then that the assumption the bridge has 20-40 years of life left meant ” there is no need for an unseemly rush.”

He said that since he has supported a tunnel option from the old toll plaza to Wynyard Point to complement the existing bridge.

Whatever certain in the government think of the option of North Shore rail -and Joyce has said he thinks the present busway and an extension of it is the preference for now - we must ensure future rail options are included in any proposal.

After all, you can train over Sydney’s harbour bridge.

As the next crossing is some decades away, it should not be affected by the current Government scramble to place a halt on immediate infrastructure plans such as the CBD link.




  1. Matt L says:

    A little slip in that last sentence Jon :-)

    We all know that the government will take the bridge option thinking it is cheaper and once again completely ignore Auckland’s wishes. By doing so they will not include rail to help kill that off and if it follows the tank farm alignment will also kill that off as well. The only consolation is that it should be about 20 years away and there is a lot of water to go under the bridge (so to speak) before we get the final say and the construction starts.

    Also the ANZAC bridge group were suggesting building a new bridge and demolishing the existing one and selling off the land around St Marys Bay. In light of the earthquake we definitely need an ADDITIONAL crossing not just a replacement one.

  2. Luke says:

    the Sydney Harbour Bridge has about a 1km approach road and rail, I really doubt we would want that in Auckland, that would mean the bridge aproach taking the length of the tank farm.
    The value that would be destroyed would mean the true cost of a bridge would be higher than a tunnel.

  3. Mark says:

    “The only consolation is that it should be about 20 years away and there is a lot of water to go under the bridge (so to speak) before we get the final say and the construction starts.”

    That level of uncertainty would still royally screw the development of Wynyard Quarter. No development, no new park. Another great legacy of SJ?

    Also, during the NZTA presentation to the Auckland Council Transport Committee last Wednesday, NZTA heavily hinted that they would NOT be making an either-or call.

    One wonders whether that is because they could not simp,y turn the results of the previous study on it’s head just because the minister wants them to.

  4. Mark says:

    “The only consolation is that it should be about 20 years away and there is a lot of water to go under the bridge (so to speak) before we get the final say and the construction starts.”

    That level of uncertainty would still royally screw the development of Wynyard Quarter. No development, no new park. Another great legacy of SJ?

    Also, during the NZTA presentation to the Auckland Council Transport Committee last Wednesday, NZTA heavily hinted that they would NOT be making an either-or call.

    One wonders whether that is because they could not simp,y turn the results of the previous study on it’s head just because the minister wants them to.

  5. Nick R says:

    It has to be a tunnel, the landside impacts of a new bridge would just be extreme, particularly on the Tank Farm development area. I wouldn’t be surprised if a tunnel has a far better BCA because of this.

    A tunnel avoids all this, they can start the bore in Spaghetti junction and run it all the way to Onewa Rd. There we go, SH1 all underground and out of the way leaving us a beautiful civic waterfront to develop. If the existing bridge is used for just CBD traffic, buses and cycling/walking, then they can pull down the Victoria Park flyover and reduce the route through St Mary’s bay from an eleven lane motorway to a six lane boulevard.

  6. KLK says:

    While we are talking aesthetics, 2 bridges relatively close to each other would look stupid (IMHO).

    Go the tunnel.

  7. Nick R says:

    It’s not just aethetics KLK, consider the impact on the ability to develop land on Wynyard Wharf, the resultant property values and the ability to attract key commercial tenants if they have a motorway running up half of it.

    I do agree that two bridges next to each other would look crap, especially as one is an old steel girder bridge and the other would be some hideous concrete viaduct thing… sorry bridge fans, but we ain’t getting no ANZAC spectacular, if they pick a bridge its because they want to do it on the cheap. It would resemble a larger version of the Manukau Harbour bridge.

  8. KLK says:

    Don’t let them see the Qingdao-Haiwan bridge….

  9. Nick R says:

    My guess would be something like Brisbane’s gateway bridge:

  10. Geoff says:

    Tunnels will just mean the road tunnels get built, with rail pretty much canned, as it is far less likely to get built as a stand alone project, funded internally. A bridge means the rail crossing gets provided from day 1, fully funded externally. So I prefer the bridge option.

  11. Joshua says:

    Geoff - look at Manukau Harbour Crossing, they decided to provide for Rail on the bridge but not build it as of yet.

    Building a bridge does not mean rail from day one.

    It will result in insuperior links both roading and rail wise. The current bridge proposal is designed for light rail, not heavy rail.

  12. Nick R says:

    I tried to make this post from my iPhone but I’m not sure if it worked, apologies if I end up saying the same thing twice.

    Anway, Geoff, Joshua, it is almost certain that a new harbour bridge would not carry rail in any form so it is a moot point. Consider this:

    Firstly a bridge couldn’t feasibly carry normal heavy rail. A new bridge needs to clear the same 45m mean height that the existing bridge does (this is one of the identified design requirements), and the maximum sustainable grade for heavy rail is 1 in 40. If we put these two together then the bridge would need to climb from ground level for 1800m to clear the shipping lane then drop over 1800m to get back to ground level again. So this makes a heavy rail capable bridge 3.6km long, that’s about twice as long as the existing bridge. Obviously this would be very expensive and isn’t going to happen!

    Secondly, a steeper shorter bridge could carry ‘light rail’ (i.e. large trams), however this would mean developing an entirely new mode in Auckland, it would mean converting the busway to a light rail line (or building an new one elsewhere) and it would mean a tunnel or a surface route through the CBD to integrate with the rest of the rapid transit network. So this is a very expensive undertaking too, and it is questionably whether it would be worth the extra cost for the relatively minor improvements that light rail would afford over the busway.

    In reality the minister has called for this bridge review because he wants to save money and do it a cheaply as possible. With that in mind a mega heavy rail bridge is out of the question, and building an entirely new light rail system (with big cost but minimal extra benefits) is extremely unlikely. A bridge from Stephen Joyce means a cheap and probably quite nasty motorway bridge.

    The only worthwhile way to get high capacity, fast heavy rail (that could integrate directly with the rest of the system) across the harbour is in a tunnel. The harbour is only 15m deep, so a heavy rail tunnel would need to be only 1.2km long, which is almost shorter than the minimum crossing distance itself. A rail tunnel itself wouldn’t be massively expensive, but rebuilding the busway and tunnelling through the CBD would be.

    A rail crossing to the Shore would be an independent project to a road crossing, they are two different modes with different design characteristics on two different alignments. It would be expensive and in my opinion it isn’t needed any time soon given the capacities left in the busway. The goal should be to extend and improve the busway so it can be used to its fullest extent.

    One of the benefits of a new road tunnel or bridge (over a replacement bridge) is that it allows the existing bridge to be used for dedicated busway, cycling and walking lanes. In my opinion a motorway tunnel from Onewa to Spaghetti junction is the best idea. Not only does it take SH1 out of the CBD waterfront and hide it underground, it means we can run the full busway right into the CBD and we can have foot and cycle crossings of the harbour. In the end we would have a six lane underground motorway bypass of the CBD, four lanes of general traffic leading to the CBD, two full busway lanes right across the harbour, a 3.5m wide two-way cycling facility and 3.5m wide walkway. It also means Wynyard Wharf is unscathed and can be developed as a premier waterfront district and park, and we can even rehabilitate St Marys Bay from having an eleven lane motorway to a six lane boulevard.

  13. Nick R says:

    Oh, and I’ll just add that building a new motorway tunnel or bridge doesn’t preclude constructing a rail tunnel across the harbour in the future when the busway is no longer sufficient.

  14. John Dalley says:

    Though there is need for a future harbour crossing which i favour to be a bridge i have always been puzzled why the clip-on lanes of the current harbour bridge could not be under piled. By that i mean what would be the issue of sinking new foundations in to the seabed and turning them from clip-ons to permanent.
    If anyone has an explanation, i would love to hear it.
    As for the new harbour crossing, i liked the look of the bridge structure as per the picture above or something similar. If it also include Tran, trains, walkways, cycleways etc as well as vehicle lanes, it could be a spectacular and picturesque addition to the harbour and tourism walkways.

  15. damian says:


    Adding rail to a bridge is not that simple I am afraid. Due to the gradients that will be required due to marine clearance, the approaches will have to be very long and for the most part elevated well about the existing carriageway.

    At a guess, you’ need to start climbing form about cook street to make the apex of the bridge.

    Tunnel is the only way forward for rail I am afraid with out making a complete eyesore on the landscape

  16. Nick R says:

    There would be no need to pile under the clip ons to make them permanent. The existing foundations are up to the job, it is the superstructure that is dodgy.

    NZTA have a mid term plan to replace the clip ons in more or less their current configuration (hence the desire for a second crossing to allow them to be out of action for a year or two), presumably using more modern design and materials. Once replaced the clip ons would be permanent and last as long as any other bridge structure.

    One consideration here is that the clip ons are weakened especially by carrying heavy freight traffic from the port, and they have recently been strengthened to extend their life. If a second crossing is built then the clip on lanes could be allocated to buses, cycle lanes and walking paths and they would be subject to far less stresses than current. Getting rid of the heavy traffic from the clip ons might extend the life of these recent upgrades indefinitely and remove the need for them to be replaced.

  17. Anon says:

    The Tunnel will be the better solution. It will remove SH1 and give us a nicer view of Victoria Park and St Marys Bay.

    With the Busway, a flyover or tunnel needs to be built between Albany and Constellation to complete the North Shore section of the Northern Busway.


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