Every weekend we dig into the archives. This post by Matt was originally published in June 2014.
Last week there was some renewed debate over the merits of the Additional Waitemata Harbour Crossing (AWHC) project, due to former Local Government Minister Michael Bassett suggesting it should start nearly immediately and made a lot more sense than the City Rail Link. I outlined why that particular argument is complete rubbish previously, but I think it’s worth delving back into exactly why AWHC is an unnecessary, wasteful, counter-productive and completely stupid project. For the purposes of this post, I’m talking about the AWHC project’s roading components as proposed in quite a lot of detail here by NZTA.
This is a debate that’s going to get much more intense later this year as the NZTA is getting ready to apply for a designation for the project. This is what they have said about it.
The NZ Transport Agency expects to progress the designation to protect the route of the planned additional Waitemata Harbour Crossing later this year. The Transport Agency anticipates that there will be a public hearing regarding its designation request in mid to late 2015.
So firstly, let’s look at the different arguments that have been proposed in favour of the additional crossing:
- It’s necessary to provide for growing traffic demand across the Harbour Bridge
- It will significantly ease congestion on the Northern Motorway
- The current clip-ons have a limited lifespan and need replacing
- It’s necessary to ensure a resilient transport network
Let’s work through each point one at a time.
Firstly, in terms of traffic volumes we have extensively documented the number of vehicles travelling over the Harbour Bridge has been very static for a number of years now and remains below 2006/07 levels. This is significant because the NZTA’s business case for the AWHC project (which suggested a cost-benefit ratio of about 0.3) assumed significantly higher traffic levels than what’s actually occurred. Also notable is that the modelling was done two years after the 2008 starting point yet used the models results which were significantly higher than what had actually happened. A case of rewriting history.
We know that generally traffic growth has been minimal over recent years, but what makes NZTA’s analysis particularly bad is that the impact of the Waterview Connection project – completing the Western Ring Route which has the very purpose of taking pressure off State Highway 1 including the Harbour Bridge – seems to have been ignored in the projections. So therefore not only has traffic demand over the Harbour Bridge been steady for the last few years, there’s actually a project coming online in the next few years which is designed to reduce traffic across the bridge.
In the (much) longer run, traffic volumes may increase again – but then again the North Shore rejected major intensification as part of the Unitary Plan so perhaps longer term growth won’t be as significant as in other parts of Auckland. The growth that does occur is more likely to be from the upper areas for whom the WRR is a more viable option should they need it. Further as people who use the bridge daily will attest, it’s not the bridge that is congested but the approaches.
“Fixing” Congestion on the Northern Motorway
The Northern Motorway is notoriously congested at peak times and I think much of the local support for AWHC is based off the assumption that it will fix this congestion. Unfortunately for the locals, it appears unlikely that this will occur – even after spending $5.3 billion. One of the reasons for this is simply how the AWHC will connect back into the existing network. The current plan is the new crossing would hook directly from the Northern Motorway on the Shore through to the Central Motorway Junction in the City. People going to the city would use the existing bridge.
In short the AWHC doesn’t provide any extra traffic capacity for through movement however what it does do is allow for a lot more capacity to the CBD. All current plans are focused on trying to reduce traffic in the city centre so this goes against everything else we are trying to achieve. In addition any increases in capacity are also going to place additional pressure on the local roads of the North Shore. Quite how the planners and engineers plan to deal with that is is unclear.
Some like to argue that by building the AWHC it will allow for the current lanes on the bridge to be turned over to buses, walking and cycling however that means we are spending over $5 billion for little or no gain in capacity. That seems insane to me.
We can also see in the modelling from the City Centre Future Access Study – which crazily included the AWHC as a reference case project – that the new crossing will be just as congested as the existing one. The two images below are from the modelling in 2021 and 2041 and show both crossings at 80-100% of capacity during the peak so for those on trips past the CBD there is little to no difference in the amount of congestion they will experience.
The current clip-ons have a limited lifespan and need replacing
Of all the arguments for the AHWC this is one of the stronger of them however even it falls over very quickly. The NZTA have said the clip-ons could last many decades longer, especially if heavy vehicles were restricted from them like what happened a few years ago while they were being strengthened.
Having recently spent $86 million strengthening the bridge’s two clip-on structures, the agency is focused mainly on its ability to cope with increasing freight loads.
Mr Town said that with careful management, there was no reason why the 54-year-old bridge could not last for another 100 years. But he said the “critical path” for bridge loads was heavy vehicles travelling on the northbound clip-on lanes, for which forecasts indicated a new crossing would be needed by 2030.
Now those forecasts are the same ones mentioned earlier which have assumed massive ongoing growth which simply hasn’t been happening and the NZTA don’t really have a good handle of just what impact the completion of the Western Ring Route will have.
But he said “one of the big unknowns” was what the completion in 2017 of the western ring route with its connection to the Upper Harbour Bridge at Greenhithe would do for heavy traffic movements.
“It will provide a genuine heavy traffic option – between 2017 and 2021 we will be looking really closely at travel patterns.”
It seems to me that we shouldn’t even be having a discussion about timing for the AWHC till about 2020 so we can see whether traffic volumes increase once again and what impact the WRR has.
Further I think there’s a way to replace the clip-ons without a new road crossing, more on that soon.
It’s necessary to ensure a resilient transport network
I think it is critical that we build resilience in our transport system however I question whether effectively duplicating existing infrastructure is the best way forward. To me that will simply shift the issue to the next weak point on the network. To explain this let’s work through a few scenarios assuming we have the AHWC as described above, these could be anything from a broken down vehicle to something catastrophic.
- The existing Harbour Bridge – as traffic to/from the city is unable to access the AWHC from Fanshawe St/Cook St then the only option would be to use Grafton Gully and the connection to SH1 from there. Put simply there is no way that single connection could cope and in the process would see huge numbers of vehicles clogging up the city centre as well as congestion likely through the isthmus parts of the motorway network.
- The AWHC – The only option would be send traffic through the CBD to the access the existing Harbour Bridge. Like the option above it would see the CBD which we are trying to make more pedestrian friendly flooded with cars,
In either scenario traffic would also be able to use the upper harbour bridge.
But does resilience have to mean duplicating infrastructure with more of the same? I believe there is more value in providing resilience through better alternatives so that
- Not as many people are directly affected should something go wrong.
- The options we have complement each other with each addressing the weakness of the other
A perfect example of this in action comes from San Francisco. In the 1989 earthquake part of the Bay Bridge collapsed cutting off an important connection between Oakland and San Francisco. Like Auckland there were other bridges available to get across the harbour but in many cases they represented a significant detour and likely experienced heavy congestion as a result of the traffic diversion. Thankfully for San Fran they also had another crossing of the harbour and one that wasn’t impacted by congestion on other parts of the road network – their BART system. That provided both a high capacity alternative to the road network and many people quickly changed their travel patterns. Interestingly after the bridge reopened a month or so later many of the new users enjoyed using the system so much they continued to keep doing so.
To me none of the arguments stack up for building another road crossing any time within the next few decades. This is exaggerated by the sheer cost of the project which at a stated $5.3 billion is far larger than any other transport project proposed in NZ to date. In comparison the current largest single project is the Waterview connection currently under construction for a price tag of $1.4 billion.
In the next post I’ll cover what I think we should do to improve connections across the harbour.