Here at the Auckland Transport Blog we have finally found a road project that seems more unwarranted than either Puhoi-to-Wellsford or Transmission Gully. This is a road project that costs more than both of those two premature white elephants combined. Yes, we’re talking about the “Additional Waitemata Harbour Crossing Project“.

We often hear how important and urgent it is for Auckland to get another crossing over the Waitemata. This message is usually swaddled in one or more of the following soothing spoken reasons:

  • Congestion is bad, i.e. your valuable blogging time is being wasted.
  • The clip-ons are going to fall off, i.e. you better learn to swim.
  • It’s always been in the plans, i.e. you can’t stop it now.

Let’s consider each of these arguments in turn and see whether they hold much sway.

First, the sweet smell of congestion – that addictive road building tonic that both demonstrates the folly of designing cities around private vehicles, while simultaneously providing the justification for  continued investment in private vehicles. This is the same circular logic that entrapped the entire city of Los Angeles for decades, and which still seems to prevail within the MoT and NZTA. The thing with congestion is that you can never beat it by building more roads – investing in the latter usually simply enables congestion to grow back, it’s like NZTA want to spray water onto the mould that covers the bathroom ceiling.

Moving along – the particularly interesting thing about congestion in this corridor is that we as a society has just invested in:

  1. The Northern Busway, which provides an extraordinarily successful (given the prevailing lack of development around stations) and relatively congestion-free public transport corridor that runs in parallel with SH1. From what I can tell (back of envelope numbers) the Northern Express is now operating at close to full cost recovery. Further only being a fraction of the vehicles that cross the bridge, around a third of all people heading southbound in the morning peak do so on a bus. This graph from ARTA is a couple of years old but shows how quickly the situation is changing thanks to developments like the busway. There is still a lot we can do to further improve the bus experience for Aucklanders, especially on the city side through improved bus lanes and facilities.
  2. The Western Ring Route, which (when complete) will provide an alternative route for some vehicle trips. From what I know, transport modelling predicts a drop of about 5,000-10,000 vpd on the bridge when Waterview is complete. As such, the WRR could reduce vehicle volumes on the existing Harbour Bridge by around 5%. Not huge, but probably enough to noticeably reduce congestion.

Conclusion #1: Together the Northern Busway and the Western Ring Route are the main congestion safety valves that Auckland needs across the Waitemata.

Second, we accept that the clip-ons may fall off when a continuous line of fully laden 40+ tonne trucks comes to a grinding halt on the bridge while being buffeted by hurricane force winds. Yes, the next time we have a hurricane that prompts some kind of lemming like heavy vehicle pilgrimage (which for some reason ends up stopping on the Harbour Bridge) then the clip-ons may become pontoons.  But does it necessarily follow that we should spend $5 billion on a new crossing? Not really, if you consider the following options as being alternatives to a new crossing:

  1. Ban heavy vehicles from using the bridge in high winds; or
  2. Restrict heavy vehicles to using the main span of the bridge; or
  3. Require heavy vehicles to divert via the aforementioned Western Ring Route.

Some of these management techniques have already been used in the past so they wouldn’t be something new. Conclusion #2: Ultimately there seems to be at least three more effective ways of extending the life of the clip-ons (perhaps indefinitely) that helps us to avoid spending $5 billion on another crossing.

Third but not least, we come to the suggestion that “it’s always been in the plans.” To understand this argument we tried having a look at the plans. The latest ones came out in 2010, when NZTA last considered the merits of the project. This included preparing some detailed drawings of how it could work and a Business Case that analysed the costs and benefits of a bridge option and a tunnel option. The cost-benefit ratio for the two options are shown in the box below, which is found on page 65 of the business case document:

With a capital cost of close to $5 billion for the tunnel option, this would mean a return of around $1.5 billion excluding agglomeration benefits or $2 billion including them (using undiscounted figures). So pretty much the same as getting $3-3.5 billion and burning it. Now you don’t have to be an economist to know that this analysis is suggesting that this project is morse code for “absurd waste of money”.

Conclusion #3: If the additional Waitemata Harbour Crossing has always been “in the plans” then we’d just respond that it damn well shouldn’t be. Or perhaps more accurately: Just because something was a bad idea in the past, doesn’t mean it will be a good idea in the future.

At this stage some of you may be thinking “case closed” – let’s strike that project off the list and move on. But wait there’s even more to this post: When reading the NZTA’s Business Case we found, how shall we say this,  “questionable” assumptions about future growth in vehicle volumes. But before going into them its time for a little pop quiz, if you are modelling traffic flows in 2010 to predict future vehicle volumes do you:

a) base it off the currently available numbers
b) ignore what actually happened and use a model to predict what the numbers were

Here are the numbers that were used which comes from page 10 of the business case:

The important thing is the 2008 numbers seem to have been generated by a traffic model, because they do not match what was actually observed. For example, the NZTA’s own numbers for 2008 say there were only a average of 154,925 vehicles per day that crossed the bridge, a difference of over 13,000. The difference in the volumes can be easily seen from the graph below, which shows actual traffic volumes (green) and predicted traffic volumes (red).

There’s a couple of interesting things about this graph: The first (and most obvious) is that the modelled traffic volumes are approximately 10% higher than the actual volumes, even before the Business Case was released in 2010. Basically, the Business Case appears to be re-writing history by using traffic volumes that are higher than what was actually observed. Bizarre eh?

Personally, I would have thought that where you had a transport model that was predicting volumes that were 10% higher than the actual observed volumes then that would be reason to re-calibrate the model so that it more closely matched actual volumes, certainly before you did absolutely anything else with the outputs – let alone argue for us to spend $5 billion. Nevertheless, it seems (from what we can tell reading the Business Case) that the red line above was the one used in calculations of benefit-cost ratios, despite actual data showing that it was 10% off the mark from the outset (NB: A 10% difference in vehicle volumes makes a huge difference to congestion reduction benefits).

The next interesting thing is that based on the red line NZTA has (somehow) concluded that the next Waitemata Harbour Crossing is needed between 2020-2030, at which point they were expecting between 188,000-200,000 vehicles per day (vpd) over the bridge. If we take the mid-point of this range as defining the “critical threshold” then we can conclude that the current crossing arrangements is maxed out around 194,000 vpd. The figure below illustrates this critical threshold as the black dashed line. We have also extended the actual volumes (green) using the modeled traffic volumes (dashed green line). The latter sort of shows what you might expect to happen to vehicle volumes in the event that we returned to the modeled “trend” for the next 30 years.

We can see that even by 2041 the dashed green line stays below the dashed black line, i.e. we have not come close to hitting the “critical threshold” even by 2041. Stated simply, the reduction in vehicle volumes observed on the Harbour Bridge in the last 5 years or so seems to have bought us at least another 20 years when it comes to developing an additional Waitemata Harbour Crossing. Why so much time? Well, because it will take us ten years to get back to the level we were 5-10 years ago. That’s why we now have so much time and why this project, if it’s needed at all, does not seem to be “urgent”.

With all this in mind I can’t understand why some people at NZTA (and certain politicians on the North Shore) seem to be pushing for an additional Waitemata Harbour Crossing to be constructed soon, like between 2020-2030. Surely the smartest thing to do before pushing this project along is to:

  1. Wait until we have completed a few projects that may impact on the need for this crossing; and
  2. Recalibrate the model and issue an updated business case incorporating revised traffic growth assumptions?

At this stage, not only does another road-based crossing of the Waitemata Harbour seem like an ineffective way to address the issues put forward, it also seems like it’s nowhere near as urgent as some people make out. I have no problem with long term planning for another crossing, but let’s not kid ourselves that it’s needed in the next 30 years. By crikey.

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  1. But you could build it almost for free with some explosives to induce a volcanic explosion and channeling the lava flow across the harbour, Play to Auckland’s strengths. Kaboom. Lava tubes are very in this time of the geological epoch.

    1. About $1.5b from Wynyard Quarter to Akoranga plus another billion to extend it all the way to Albany. That’s for conventional heavy rail. Vancouver Skytrain style light metro could be quite a bit cheaper.

      1. If it is $2.8bn for the CBD rail tunnel, then I don’t see how a similar length tunnel under the harbour can cost much less. One has stations and the need to purchase property (which we’ve been told is only about $250million… which seems super optimistic), but the other is under the water and that must add complexity and cost.

        Plus, you need a tunnel from Wynyard to somewhere east of the CBD, with stations. Another $2.8bn?

        1. The CRL is, to be frank, a horribly constrained alignment through and under the CBD that has fixed connection points at both end, which massively restricts the ability to put it on the path of least resistance. That means we have to end up with things like stations 40m below ground in a bored out cavern that cost $250m each. Boring the actualy tunnel is one of the cheaper components of the scheme.

          A harbour tunnel would be underwater yes, but otherwise it would be a nice long gentle straight tunnel that could pop up wherever it is convenient between Northcote Point and Takapuna. Also all of the land required is already owned by the council (watefront side) or NZTA (Shore side). Two Km of tunnelling under the harbour, then a simple widening of the causeway up to Akoranga. The hardest bit would be the city side connections from the harbour tunnel to Aotea.

        2. In fact, the twin bored tunnels of the CRL were just $126 million (plus contractors’ margins, design, etc.) in the business case. The cut-and-cover bits at each end cost twice as much, let alone the stations!

          Does $1.5b for the North Shore tunnel include rolling stock, a depot, etc.?

        3. Even so it still doesn’t increase the overall cost that much and and works out at about $37m per KM (roughly two 2km tunnels).

          Wynward to Onewa is about 3km so once you add in the cut and cover sections and getting transition points between sea and shore, design costs, contingency etc. you are probably looking at around $500-$1b then another say up to another $500m to get the remaining 1.5km to Akoranga (which is where the business case went to) so $1.5b is probably about right.

        4. A very useful link Matt, thanks. As you say, the tunnelling itself is a relatively small part of the total cost. IIRC the Vector tunnel (Penrose to Hobson St) cost about $100m (back in the late 90s, so needs adjustment). That tunnel is ~10km so is 50% longer than the twin CRL tunnels, but only 3m in diameter (I’m guessing the CRL tunnels are closer to 6m so a lot more dirt, but I can’t find that reported anywhere).

          The Vector tunnel used a roadheader for the bendy bits from Hobson St and a TBM from Penrose (pretty much a straight line to the city under the motorway). The route was also constrained by road reserves to a large extent, as with the CRL. As I recall the roadheader reached its target first so just kept going. And you can run a diesel train through this tunnel too (well, a small service unit fitted with a catalytic convertor).

        5. Thanks Matt. The Vector tunnel was actually closer to 3.5 OD so the CRL is roughly twice the diameter and 4x the volume, although the cost adjustment may not be directly proportional.

  2. The purpose of the second harbour crossing is, of course, to buy the Government votes from the upper-middle-class denizens on the Shore who would rather send their kids to a state school than use public transport. It’s a political decision, in other words.

    1. Weirdly the PT modeshare for trips from the North Shore to the CBD is well over 50%. Even without dedicated PT lanes over the harbour bridge or northbound through St Mary’s Bay.

  3. The facts of this seem unbelievable? If the groups supporting the central rail line used figures that were 10% wrong as a starting point it would be big news. Can these details be passed onto the NZ Herald or TVNZ or such? This is a natural disgrace and should be on the national stage especailly at a 5 billion dollars cost

    1. Yes on the surface at least it does seem unbelievable – but for now let’s give people the benefit of the doubt, i.e. that there’s some reasonable explanation that the numbers are out, and in turn give NZTA and their consultants an opportunity to correct the numbers and re-issue the business case, if so required.

  4. The saddest aspect of this situation is that it shows just how pervasive and corrosive to objectivity the highway obsession is at the top of our transport institutions. This route is the site of the most obvious recent case of investment in Transit systems saving us all from a much much greater cost in highway expansion. The first chart above clearly shows that it is the Northern Busway and not merely a drop in travel that has reduced volumes across the Bridge. Because the number of people crossing the Bridge has risen while traffic volumes have dropped. This is despite the fact that its most effective feature, its clear right of way, is incomplete not extending over the Bridge itself. From this we can conclude several things that reflect very poorly on how this vital area of our economy and society is being run.

    Further improving passenger infrastructure and services over the Harbour could postpone the need for more general traffic lanes indefinitely. This is not mere speculation; NZTA’s own data shows that an incomplete busway has been its best investment on this route since the Bridge opened. Currently there are 12 general lanes crossing the Harbour with no other modes supported. Total Mono-Modality. Why is there no examination of proceeding with the missing modes alone in this report? We know that almost every other course of action would be cheaper than building yet more massive road infrastructure, and many are also likely to be better yet they are not even considered.

    And there are so many options:

    1. Do nothing; looks pretty good, that huge investment in SH16, SH18, and SH 20, is supposed to achieve something right? AT are improving the whole bus system in AK over the next few years, likely to make bus travel between the Shore and City more appealing. And within the Shore too.

    2. Accelerate improvements and extension of the Busway itself. Even better; why not see just how clear we could make those general lanes for those who prefer to drive there.

    3. Take the lesson that PT investment is often the best way to relieve congestion in cities and study the whole of Ak through a multi-modal lens: Consider where additional funding is needed for breakthrough PT infrastructure in all of AK: AT are currently squeezed for funding to improve bus, train, and ferry services all over Auckland, including the NorthShore and the Central City. Spare 5 billion? Why not consider what 500 million a year for 10 years would buy in congestion relief across the region, or even 50 million over hundred years?

    4. If a much quicker and more future proofed system is still desired take a serious look at the various options for extending the rail system across the Harbour as the way to step up the success of the busway. The report prices a rail crossing at 1.6 billion. Or including conversion of the Busway to Albany at 2.5 billion. As the whole PT system in AK will soon be based on a transfer model there is a strong argument for building the rail to Takapuna via the Akoranga Station and running the Busway as it for passengers to connect at these two points before further extending the line up the current Busway. This line would connect through Wynyard Quarter and to the City Centre at the new Aotea Station in the heart of town, as it would clearly happen after the CRL and the line to the Airport. A direct North Shore to Airport service on modern electric trains, pretty handy.

    But, alas, as this clumsy exercise from NZTA shows they don’t seem to be capable of thinking objectively about transport needs and solutions, but only of where can we put another massive highway for whatever the need and at whatever the cost. We know this is the current government’s express preference but it is surprising that it appears that these well paid professionals don’t display more backbone or professional pride in their work.

    Or, is the pressure from above so narrow and bullying, that someone was happy to produce such a poor case in the expectation that even amateurs would be able show it to be so weak…?


    1. 12 lanes? If you’re counting the Upper Harbour Bridge, that’s 13 lanes (the UHB has 5), and there is a walk and cycle crossing alongside it (not that there’s anything to walk to). If you’re not counting it, the AHB has just 8 lanes of CARS CARS CARS.

      Though I’m sure a certain someone will be along in a minute to tell us we have 8 car lanes and nothing else because people love cars so much.

      1. Ooops yes of course, how could i forget a traffic lane? Not like that’s all there is…. and there are some overpriced ferries too.

        Talking of active modes, is it just me or doesn’t everyone think it is insane that we might be able to walk and ride over the bridge soon, but only by paying a toll? Errrr? So cars are free but walking/cycling will be taxed…. do they have a dictionary at NZTA?, perhaps they should look up the words ‘multi’ and ‘mode’….. Or is it that the decades of greedy whining from the RUF and the AA have worked and ‘transport’ is now defined solely as only meaning movement in a tin box, everything else is recreation or something; trains, buses, boats, bike, shoes…..

        1. It is completely insane to pay to walk across a bridge that was built at taxpayers expense a half-century ago, when cars cross for free. The only possible revenge is building a railway station under the street in front of the AA building… then digging a rail tunnel from there under the harbour.

          But apart from that, how are they going to collect the toll? HOP card gates? I would just jump the gates (assuming I ever wanted to go to the North Shore). Or are they going to pay a bunch of people to stand there and collect tickets? It doesn’t seem like it would be cost-effective.

        2. It’s the only thing the current government – who owns the bridge – is grudgingly willing to support… so don’t diss it. if it can stand on it’s own, and be built that way, it’s great compared to having no option at all. If someone later is willing to see a political upside to removing the walking / cycling toll despite the expected whinging from a few people (“We KNEW we taxpayers would have to shell out in the end!”) that’s always an option.

  5. I thought the clip-ons were eventually going to suffer metal fatigue even if mitigating actions (restricting heavy vehicles, etc) were taken?

      1. That’s good to hear. I’ve read about the corrosion in the Forth Road Bridge near Edinburgh that has cut its projected life from 120 years to maybe as little as 55 years. It’s a suspension bridge and the issue is that the corrosion is weakening the cables. They’re building a replacement at probably an enormous cost.

        Meanwhile, the adjacent rail bridge is a solid lump of metal that has been in place since 1890 and shows no signs of weakening. In my opinion, it is the ugliest bridge that I have ever laid my eyes on. Most people seem to disagree with me.

        1. The design of the Forth rail bridge was heavily influenced by the earlier Tay bridge disaster where a poor design and materials contributed to the bridge collapsing with significant loss of life. The Forth bridge can be viewed as an over-compensation. It’s not pretty but it has been an outstanding structural success.

    1. I distinctly recall reading in the report on the recent strengthening works that they would last indefinitely if we returned to managing heavy vehicle access to the clip ons.

      1. Ah, but there’s the rub – heavy vehicles are getting heavier, not by a little but by a lot and that is a result of government policy. I must find the time to wade through the NZTA reports to see how the HPMV (sic.) matter features in discussions of a new crossing. The trucking lobby is applying pressure for more routes to be made suitable for heavier vehicles

        1. I don’t know if there has ever been the suggestion of allowing HPMVs on the harbour bridge. Definitely don’t need to with the WRR completed.

        2. I have skimmed the documents and can’t see any reference to them but will dig deeper when I have the time.

    2. As of last week, NZTA’s project manager for the second harbour crossing has stated that if heavy vehicles are managed, they believe the old bridge (including clip-ons) can pretty much last indefinitely (50 years plus, certainly). Maybe they eventually have to have all trucks on the central span, but there was certainly no talk about them falling into the drink…

  6. An excellent, logical and well-considered post. I worked on the Northern Busway project and at the time was not entirely convinced of its efficacy, but the passenger stats support it, so I am pleased to stand corrected. Is it operating at capacity yet (at peak times)? If not, what is its capacity (ignoring the pinch point on the bridge)? Is there a comparable BCR available for a rail tunnel crossing?

    Re the clipons, I thought the ban on heavy vehicles using them was still in force, despite the strengthening. My limited understanding is that this prohibition was crucial to extending their life by minimising flexing. But at least a steel bridge can be improved, not like the Newmarket Viaduct with its hollow piers and inadequately prestressed deck. Presumably corrosion is addressed by ongoing maintenance. Off topic, but I recall the Millenium Bridge in London which initially had excessive sway, not in any danger of collapse but disconcerting to users. This was fixed very cleverly by installing dampers at great expense.

    Matt L, I totally support your view that if computer models don’t represent the real world reasonably accurately once real world data are available, then the model should be reviewed and revised or scrapped. It appears that NZTA has not done this, so I endorse your criticism. And you have been generous to simply redraw their graph from a lower, ie real, starting point when you could easily and justifiably have extrapolated the downward trend. At the risk of getting another beating from Stu, may I say that I wish those who make predictions based on climate change models would adopt the same level of professionism as you propose here, ie adjust the models to fit real world data and thereby correct their predictions.

    1. Needless to say it won’t only be Stu. I think that writing your last sentence must be easier than understanding the principles of climate change modelling.
      The 2010 IPCC report used only data up to 2006. The real data since is tracking worse than the IPCC’s worst case scenario. We’re going to hit a 4 degree rise by 2060. i.e. a catastrophe in our lifetimes. I think the IPCC shouldn’t be so damn careful about political sensitivities, and should tell us the cold hard truth.

        1. Nope, it was as off-topic as your initial comment on climate change modelling. Economic and traffic modelling are a different beastie to climate modelling. They’re probably closer to fashion modelling. It got my goat a little as, and I don’t mean this to be argumentative, you obviously know very little about climate modelling. Do you not think that they check their models predictions with actuals? They actually run their models backwards and check how past predictions went to actuals too. The models are highly tuned, complex, analysed for accuracy and scientifically robust. The first to suggest otherwise knows zip about them.

        2. I don’t want to inflame the topic, but jonno1 I would suggest you read this:


          To see how climate models are validated against historical data. This is not an argument in favour of climate change, just an observation that the models are extensively calibrated and then validated. Basically, climate models are used to “backcast”, so as to provide a transparent way of seeing how they perform at predicting historical trends. Much more ballsy and robust than transport modelling!

    2. …may I say that I wish those who make predictions based on climate change models would adopt the same level of professionism as you propose here, ie adjust the models to fit real world data and thereby correct their predictions.

      They do. In fact I was surprised that one of the distributed models that got computed actually started the modelling at 1920 but I realised, after a bit of thought, that it’s a reasonable way to test a model. Model the past and when it’s within reasonable bounds use it to project the possible futures.

        1. A radical idea!
          When we eventually did such an exercise for the NW Rail Utilisation Study in the UK, we discovered that the tried and tested demand forecast model – that everyone had complete faith in – was systematically underestimating the impact of GDP growth on railway patronage by a significant portion: the train operators were identifying 10% growth pa over the previous 3 years and the model (looking from the past to the current time) was suggesting it would be something like 7%pa.

  7. It may be worth investigating who is set to gain from this project financially. Someone (or groups) will be set to make $5bn out of this project. Maybe it’s worth finding out who gets this money and perhaps consider the benefits to them. You may be interested to find that most of the “experts” that the advice comes from will be the ones getting most of this money!

    1. Perhaps. But right now I think we’d be better off working with NZTA and the industry to improve the way we approach transport modelling and business cases. This is hard stuff, not easy, and (in my experience) people genuinely do their best, i.e. there’s not much perverted interests involved. What we do know is that there’s “optimism bias” – and this seems to apply equally to all models, where people working on a project become invested in the project and sub-consciously make decisions that make that project look artificially attractive.

      While this may sound like the consultant cow fertilising their own paddock, I’d suggest that what we actually need to do is invest more in transport modelling. For example, maybe we should be re-calibrating and re-validating the models every year, rather than every 5 years. After all, what’s spending $500k p.a. when it helps you make more informed decisions on exactly what year you need to start spending $5 billion? And make the process more public, e.g. show forecast traffic versus actually traffic for major streets in Auckland.

      Just like these guys have done with their climate change model:

      1. Hi Stu. Is there a point in modelling where you have to accept the trend for what it is? (In this case declining or at best flat lining?). Or is a growth paradigm integral to the model?

        1. I’m not one for accepting trends – I think there’s a lot of value in trying to explain them, even if one can never get the full picture quantitatively speaking. What’s fairly clear is that our current transport models are not explaining what’s currently happening to traffic demands, and that we need to find out why.

          But I’d hesitate to suggest that we should avoid modelling altogether. It may be, for example, that simply by updating some of the underlying assumptions that you would find they could predict Harbour Bridge traffic volumes fairly well. What we can’t do, as this post nicely highlights, is assume that the current models are going to give us the right answer. But that’s the same for any model – be sceptical!

        2. P.s. Growth is not inherent to the models – in some places by 2041 they show a declining demand for travel in line with an ageing population, for example.

  8. To play devils advocate: What about security / redundancey etc. Won’t NZ’s powehouse city come to a grinding halt if the harbour bridge is taken out of operation for a year or so due to a ship collision or natural disaster?

    1. Yes that is perhaps the biggest benefit of an extra crossing but remember there is still the upper harbour route and if something like that happened the proposed tunnel wouldn’t be much use anyway as it doesn’t connect directly to the city as it is intended to bypass it. A rail only tunnel could provide the contingency for commuters while the upper harbour route could be the contingency for freight.

    2. But how much are you prepared to pay for security/redundancy? Is this the weakest part of the network? Is it the cheapest to duplicate? And how much redundancy does a second crossing really buy you? A large earthquake would probably knock them both out.

      Another way to think about it: $5 billion = approximately $300 million per year in interest. So if we can defer building this bloody thing by 5-10 years then we’ve saved about $1.5-$3 billion dollars. That in turn can be used to build another harbour bridge in the event that the current one falls down.

      Basically I’m saying that from an emergency perspective it’s probably better to save the money for the rainy day, rather than blowing it in anticipation of the rainy day. Sure the North Shore would suffer in the event that the AHB was taken out – but I think you’d be surprised at how quickly we could get a bus only bridge back up if we really wanted to.

      1. Ferries have a high peak capacity and could be used to shuttle a lot of people over the harbour in the event of a catastrophe. How about NZTA buy a half share in the Great Barrier car ferry too. In the even of a catastrophic bridge failure they can use it to shuttle trucks across the harbour. How is that for a back up plan?

        A rail tunnel would be the best bet, it could singlehandedly move every last person on the Shore over the harbour and back three times each in a day.

        1. Ferries would only be useful for a very small fraction of the existing traffic, and do even less for freight. HOWEVER, the western ring route would provide a second option, so redundancy for a CATASTROPHIC event is already there. You don’t expect that after a catastrophic event you should still have the same level of service! Or we would all be building a second (empty) city somewhere in Northland, just in case we ever need to move there if a major volcano erupts, say, in the Auckland CBD and kills off 90% of the city’s dwellings after a few weeks of ash and lava deluge. Redundancy shouldn’t be used to simply duplicate to existing standard – redundancy is for emergency levels of service, until you can rebuild a new bridge.

        2. Max, I think you’re right. Hobart managed when it lost it’s Tasman Bridge when a zinc ore carrying ship crashed into it and brought it down. There was a 2nd bridge up near Glenorchy, about 10km north, and they put on more ferries. Auckland would manage the same.

        3. I wasn’t suggesting they could meet all the existing traffic demand, but they could maintain a functional public transport system with buses feeding to ferries at Devonport and Birkenhead. The freight ferry thing was a joke, we have the upper harbour motorway of course, plus the Riverhead Rd, and SH16 north.

  9. Interesting to read the latest article in AA Directions about Auckland transport issues –
    I particularly liked the quote about the Akld Spatial Plan: “…it contains controversial projects, like the $2.86 billion City Rail Link, but it also has projects vital to the future of Auckland, such as the additional harbour crossing.” Biased much? Of course he *could* be talking about the rail-only crossing…

    1. Also, the old “motorway network is yet to be completed”. This is why this blog’s future rail maps are so useful – we too can say “the rail network is yet to be completed”.

  10. Great stuff Matt, especially the graphs. If there was a moving average on top of these graphs the trend would be still heading down. I’m suggesting that the “modelled trend”, if we ever get back to it, is still years off…

  11. It would be really interesting to see what the projected patronage and capacity of the Busway is into the future. That would assist in determining whether an addtional crossing is required for the non-bus users. AT appear to be stalling the the process of expanding the capacity on the Busway (and other corridors) somewhat by not changing rules that would allow European standard Decker buses to run in NZ. Axle weight and width issues to be worked through to get this across the line. Hopefully common sense prevails and we see AT and NZTA working together to adjust rules to suit NZ operating conditions, but to also deliver a solution to Auckland PT users without excessively clogging up the CBD. Suspect that standard sized bus capacity in the CBD will be excedded within next 5-8 years based on recent patronage growth.

      1. My understanding it is that the main issue is to do with axle weights when these buses are fully loaded. They are fine for tour buses as everyone is seated but on a PT buses there will be a lot of people standing and that is pushing them over the NZTA set limits.

        1. Add an extra axle? twin steer? the rest of the world seems to cope with 3 axles. The ones in Hong Kong did have a no standing upstairs rule.

  12. I remain an optimist, and given the long timeframe on this project potentially being executed, there is plenty of time to make the arguments (as succinctly written and graphed above), and also for the evidence of continuing change in transport behaviour to be so evident that it cannot be ignored. Factor in the new bus network and electric trains by 2016, continued upward trend in oil costs, and I will be surprised if a vehicle-only option ever gets underway. Public transport options will seem much more appealing and economic. Of course, a change in government policy would also help.

    1. Great presentation and analysis of the data.. it makes a compelling case!

      Looking at the chart of vehicles per day crossing the Waitemata, you find find strikingly similar stats right across the developed world. Like this chart of car miles travelled in the USA, which shows such extraordinary correlation, it might almost be drawn from the same source data and scaled up..

      If this were simply a technical problem there would surely be little or no debate, leaving forecasting difficulties aside, (although of course that isn’t reasonable)..

      But like several subjects here (CRL comes to mind) this one looks like a “wicked problem”.. as Rittel and Webber put it. It’s a one-off (no chance to try it again if we get it wrong.. At least for decades.. unlike Churchill’s American friends, LOL).. so many stakeholders (including ultimately a decent proportion of the population of NZ, or in fact all of us if you consider the vast sums involved).. an investment that represents a $ 5 bn bonanza for some.. but a disaster for others.. a zero-sum game of Cars v PT.. a polarised and politicised debate.

      I’m not sure that it helps that it’s a politicised debate, but maybe it helps to frame the problem in those terms.. see it for what it is. That’s not to decry the value in analysing, explaining and exposing the complex technical issues here in order to inform the picture.

      But anyway, in a political context.. can we say that Time Is On Our Side? I’m also am optimist. Fast forward three and a bit years, what does the chart look like in 2016? Still bumping along at 150,000 vehicles / day quite likely, or maybe less? I doubt any tunnelling machines will have been ordered by then. therefore can we collectively kick this into the long grass? If so how? And at what cost? Is there a better option (wicked problems are all about better and worse not right and wrong)?

      1. Yep very similar, have a look at my latest post for a comparison between some US numbers and the harbour bridge numbers.

        You are correct that this is largely a political issue, it is on the books because a lot of people think it is a good idea but they haven’t looked at the facts and so politicians who are eager to please keep promising it. Pretty much all transport spending for the next 10 years is tied up in the existing RoNS so short of the government funding it out of other sources it is likely that this project will have a bit longer to stew and we will see if the recent trend continues or if it changes back to what it used to be.

        As for a better option, I feel that the best solution would be for rail only tunnels to be built first. It was estimated in a study earlier this year that it would cost ~$2.5b to tunnel from Wynyard to the Shore and to convert the busway to rail. That would provide a very attractive and quick trip under the harbour so would probably see PT mode share jump much higher which could significantly change these numbers again.

        1. Totally agree.. the better option is to build a rail Waitemata crossing first.

          What I meant was, if this is the goal, then is there a better way of achieving this than trying to delay any decision to build a road tunnel? The downsides of that would seem to include very large sums contining to being spent on the business case.. that could be better invested elsewhere.

    2. Totally agree. I think the sheer cost of this project means it will not happen anytime soon and the need to search for cheaper options will be compelling.

  13. If this project did proceed, $5bn would be just the start. Think of the widening that would have to occur through spaghetti junction and north of the bridge… Or is that incleuded in the 5bn figure?

    1. Nope… in the same way that the SH16 and SH 18 isn’t included in the Waterview figures: We calculate that the Western Ring Route work all up is around 4billion, but you will never see that figure mentioned by the government or NZTA: Slice it up and make it look cheaper. Where as the CRL figure includes double tracking the Onehunga line, additional trains in the 2030s…. Of course no road figure includes the vehicles or the fuel to move them over any period, let alone the land lost to extra car parking and so on…. They even have the cheek to claim agglomeration benefits, never the additional costs on society of forced vehicle ownership….

  14. continuous line of fully laden 40+ tonne trucks comes to a grinding halt on the bridge while being buffeted by hurricane force winds. Yes, the next time we have a hurricane that prompts some kind of lemming like heavy vehicle pilgrimage (which for some reason ends up stopping on the Harbour Bridge)

    With all this in mind I can’t understand why some people at NZTA (and certain politicians on the North Shore) seem to be pushing for an additional Waitemata Harbour Crossing to be constructed soon, like between 2020-2030.

    Well, at least they want to wait to build it until after 2020 because, after then, it will be obvious that expensive roads won’t be getting built no matter how much some people will still try to cling on to last century.

    1. You’re right there. The road builders are going hell for leather because they know that in a few years’ time people will laugh at them.

    1. Am able to answer own question with the help of a spy…. [no not a big German]

      “Lot of talk about bridge vs tunnel, some talk about building a combined tunnel catering for 3 lanes and a train track underneath the deck. A mention of the Auckland Transport blog article – but no mention or let alone discussion of the criticisms. Obscene asides like a 12-14 lane bridge replacing the old bridge fully (which, admittedly, they didn’t support as an idea – they want two links, and feel the benefits of recovering the old St Mary’s Bay foreshore wouldn’t make up more than 250 million of the cost). No discussion of the impacts either side of the bridge, or the capacity question. Some questions on tolling, they basically admitted they’d have to toll both links and claim Greenhithe as the un-tolled alternative (but didn’t discuss the Western Ring route as a capacity valve for AHB). Lots of missing parts, really.”

      1. We just need to stall the process. Getting Shorites on the right side would help, and all I think that would take is to tell them that both the new and the old crossing would have to be tolled. If they want a third crossing, then they won’t be able to leave the shore without paying a hefty toll.

        By all means let them plan the crossing, but not start funding or building the thing without a very compelling reason. Every year that ticks by means less traffic growth, more PT demand, more fiscal scrutiny and less compelling argument for a hugely expensive motorway crossing (that will inevitably lead to more motorway construction on either side).

        I can’t image in the future when we have the new transit network, electric trains whistling through the CRL and intensification in central areas around housing demand, that anyone could justify spending $5/6/7 billion a six lane motorway tunnel into the central area.

        1. The thing as envisaged by NZTA will not happen I’m sure of that, but that they are wasting money and time designing and promoting it just shows how hopelessly stuck in the past they are. It is an institution showing every sign of being unable to understand a changing world. Although I accept with a government and boss that is even more retrograde and wilfully blind it is perhaps a bit harsh to expect it to show too much flexibility….?

  15. I am a little concerned about the recent planned changed to bus routes may LOWER the PT usage. Currently there are a number of buses which start in suburbs, then get on the busway and go to different parts of CBD.
    It seems like the new bus design would prefer people to get on a feeder, off at the busway, on another bus to Britomart and then for some on another bus. I think this will be slower / more inconvenient for some users.
    If we set the long term goal at 10,800 bus users across the bridge per hour this should negate the need for a 2nd crossing. This is 3 [people per second – or a more comprehensible e 45 people on a bus every 15 seconds. The do not just come from the bus way- some come from Takapuna and Onewa road as well. The hard bit could actually be getting 3 people per second on a bus. The current bus way stops probably cannot get a lot more buses through at peak- they are often waiting for spaces or waiting to pull out. Therefore I do not think the feeders stopping at the busway stops will actually help – I think we need the thru buses (meaning ones with people picked up in the suburbs or returning to them going thru the busway stops

    Any thoughts?

  16. I think there are two arguments that are being confused here by advocates of the third crossing.
    1. We need more lanes.
    2. What happens in a disaster and the bridge is rendered unusable?

    The evidence for point 1 is not really there. Traffic is clearly declining on the bridge for a variety of factors.

    Point 2 is much harder to quantify due to the uncertainty around that scenario. Obviously if the bridge was rendered completely unusable until replaced it would create a certain level of disruption. Quantifying that level of disruption would give us an indication of how important an alternative crossing is. If the disruption would cause a certain amount of economic damage then it may be worthwhile building a second crossing as a form of insurance. You then need to consider the likelihood of such an event if it is highly unlikely then we need to factor that into account on the other hand. Until those numbers are crunched then we can make an informed decision around whether a third crossing is needed as insurance. In either case I don’t see any need for more lanes and should the risk and damage to the economy in the event of catastrophic bridge damage be deemed sufficient to warrant a new crossing then steps should be taken to lower the priority of the existing bridge. Possibly through a reduction in lanes, inclusion of bus lanes, lower speed or even the removal of the clipons entirely if they are degraded enough. Essentially make the new crossing as a by-pass of the existing bridge and refocus it to being a local/public transport/cycling route over an historic structure.

  17. If the harbour brudge did have a catastrophic event ( persume here would be Earthquake , volcano or tsunami) could it take out a new bridge as well? Would it then be better to build the crossing after this event rather than one to be busted? Can engingeeers say how much stronger a new bridge would be?

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