Over the last few months we have done quite a number of posts looking at the issues of a potential new harbour crossing and I think that it may have started to frustrate some from the North Shore. particularly councillor George Wood. He has became much more vocal on the issue though social media and calling for the bridge to be built as soon as possible. Well it seems that it has attracted the attention of the Herald who ran a piece today about it that has provided some useful information about the need for the project. I did have a little laugh right at the start as one of the things I had questioned earlier in the year was if there would be any North Shore politicians who would actually stand on a platform of not building another road crossing
North Shore leaders will this year ramp up calls for a new Waitemata Harbour traffic crossing, even though the Transport Agency does not believe one will be needed before 2030.
Although the agency expects to update an application to protect a preferred route for tunnels under the harbour towards the end of the year, Auckland Council member and former North Shore mayor George Wood fears complacency setting in.
He says community groups such as the Northcote Residents Association want to be involved in planning for a new crossing but are being kept in the dark about a proposal which follows at least six studies since 1986 and doubt about the longevity of the existing harbour bridge.
Arguing for the bridge on the grounds that it is old and could fall apart seems to have been a mainstay argument for those that want a new road crossing and helpfully the NZTA have addressed this.
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.
Even so, the agency did not want to build the new crossing too early, for cost reasons.
“It’s expensive, so getting the timing right is the thing,” he said.
The agency in early 2011 estimated the cost of a pair of road tunnels at $5.3 billion compared with $3.9 billion for a new bridge, and the Auckland Plan cites a figure of $5.8 billion to include future provision for trains.
Mr Town acknowledged that technological advances were likely to reduce tunnelling costs, while those for a new bridge were unlikely to fall markedly.
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.”
So the bridge is obviously fairly structurally sound and the issue then becomes a question of when the clip-ons need replacing. The NZTA seems to admit that it will depend a lot on what happens after the completion of the Western Ring Route. You may also recall that we found that the traffic predictions that had been used in the previous business case used incorrect data so it is quite possible that combined with the WRR this could see the need for replacing the bridge pushed out a lot longer than 2030.
The other major issue with a new crossing would be the impact on the city centre. The current thinking is for the new crossing to link directly into the existing motorway system and to turn the harbour bridge into a kind of big off ramp. By taking the through traffic off the bridge, it would leave a hell of a lot of unused capacity on there which would have the effect of making it easier to drive to the city. That would severely impact not only the performance of the Northern busway but would see potentially thousands more cars per hour dumped into the city centre when all of the councils plans are focused on trying to reduce vehicle numbers that area.
So far everything seems to point to the conclusion that we are both unlikely to need the crossing for at least a few decades and that even then we might not want it due to the impact it would have on the rest of the city. That kind of brings me back to my question from earlier in the year and wonder when will we get a politician who is brave will actually stand up and say this to the residents of the North Shore?
I think the other thing worth pointing out from this article is it confirms that the NZTA are now looking at a combined road and rail tunnel like has been done in some places overseas. In this situation the tunnel diameter is big enough that a train line can be run below the road deck as shown below. If we must have a new road crossing then it does make sense to do it this way and it is interesting to see the NZTA say that the tunnelling costs are likely to reduce as the technology improves. My preference at this stage however would be for a dedicated and much cheaper rail tunnel first and to only build the road crossing if it is still needed after that (the business case costed a rail tunnel at $1.6b vs $5.3b for a road tunnel).