This post was largely written by good friend of the blog Warren S however I have added some parts too.
Seeing the picture recently of the 14.5 diameter tunnel boring machine to be used in the construction of the Waterview motorway connection started me thinking about the cost of infrastructure and the difference regarding tunnelling for road and tunnelling for rail. Actual costs are hard to come by but certain aspects are evident.
The cost of the Waterview TBM is given as $54 million. I suppose this cost is not great in the overall scheme of things, because the overall cost of this project is roughly $1.4 billion according to the NZTA. The original cost of $54 million will have a residual trade-in value of around $10 million when its Waterview work is done. That is a write-off of some $ 44 million.
I then thought I would compare this TBM with the ones they are using in London for Crossrail. They are all made by Herrenknecht though the U.K. ones come from Germany while our one was manufactured in China to the German design.
Right now Crossrail are using eight TBM’s all simultaneously boring away somewhere under London. These machines are less than half the size of what is being used at Waterview at 7.1m in diameter. Being smaller they also come in considerably cheaper at about $20 million compared to the $54 million for our monster. And interestingly with Crossrail 85% of excavated material is being moved by rail or barge – not by road – so eliminates messy roads during construction. Combine this with the fact that there is also less spoil to remove and less concrete needed to make up the tunnel lining and the costs for tunnelling are likely to be significantly cheaper.
Crossrail is scheduled for completion in 2018 with a capacity of 24 trains per hour or roughly one every two to three minutes, that’s similar to what we can expect from the City Rail Link. While we could probably debate all day the merits of what train technologies to use, using our new EMUs an example each train could easily accommodate 750 passengers. At 24 trains per hour that is a capacity of 18,000 people per hour per direction through a rail tunnel. By comparison if we’re lucky the Waterview tunnels – at three lanes wide – will be able to carry about 6,000 vehicles per hour per direction or about 8,000 people if vehicles were carrying a high occupancy rate.
So some of the benefits compared to a motorway sized tunnel are:
- Smaller and cheaper TBM to do the job
- Less excavation required for rail.
- Rail will be more efficient – one line equivalent to two and a half motorway lanes or better.
- We are not left with a sole reliance on a motorway system can lead to stagnant chaos and long delays when there is an accident as happens frequently. An efficient metro at least gives us a viable alternative.
Being cheaper and having more capacity definitely raises some questions about how we deal with a future Waitemata Harbour crossing. We have seen traffic volumes on the bridge decline over recent years while at the same time more people than ever catch a bus across the harbour. Further once Waterview has been completed it is likely to take even more pressure off the bridge. At the moment the plans are to build a combined road and rail tunnel which might be similar to below however it is expected to cost roughly $5 billion.
With traffic falling – and potentially continuing to do so – it has removed the congestion/traffic growth argument from the debate and the NZTA have now shifted the discussion with them now saying that a new crossing is needed so the clip-ons can eventually be replaced. The problem is they are being hammered at constantly by heavy trucks (although replacement isn’t needed for some time yet). If the main issue is the clip-ons then we need to be asking if the problem is really worth us spending $5 billion just to avoid having to close two lanes while they are replaced. So what’s the alternative?
A rail tunnel under the harbour.
The idea is fairly simple, we build a much cheaper rail tunnel under the harbour to at least Takapuna, if not further up the busway and linking into the Aotea station on the city side. That provides a massive increase in capacity across the harbour and we use that extra capacity along with other tools like road pricing and demand management to encourage as many people as possible to use the rail services. We then close the clip-on lanes (one side at a time) and replace them. That could leave us with replaced clip-ons and with rail across to the shore without the astronomical price tag currently associated with the harbour crossing project.
The Waterview motorway connection would appear to be a high cost ‘gold-plated’ project but it is the last link in that chain. After that I believe we have a strong chance of achieving long term value for Auckland with the CRL and ultimately a rail tunnel link to the North Shore.