A great article by Brian Rudman on the Waterview Connection in the NZ Herald today:
Long, twisted road to tunnel backflip
Think of a figure, double it, add your age and subtract the number of eels in Oakley Creek: that, it seems, is as good a guess as any for the price of completing the Waterview Connection.
I’m not surprised Transport Minister Steven Joyce and the NZ Transport Agency waited until the eve of the Christmas exodus to sneak out the highly embarrassing news that a tunnel was, after all, the most cost-effective and environmentally sensitive way to join State Highway 20 up to the Northwestern Motorway at Waterview.
Mr Joyce called this backflip, a “fine-tuning of the alignment”, while Transport Agency chairman Brian Roche’s press release was even more buttoned-up, referring to “design improvements”. The only reference to cost was by Mr Roche, who said the new tunnel “can be completed within the original project budget and is the most cost-effective option for constructing this section while also responding well to community concerns”.
In other words, at Christmas 2009, a three-by-three-lane tunnel could be built for around $1.15 billion. Yet just 10 months before, Mr Joyce signed the death warrant for the defeated Labour Government’s similar tunnel project, saying costs had blown out from $1.89 billion to “in excess of $3 billion”. On closer examination, his bloated $3 billion included all sorts of add-ons the Labour-backed plan did not.
I particularly like that first paragraph, and it is oh so true. NZTA have a fair amount of explaining to do as to how this latest option can be built for half the price of the “previous to previous” option, when it’s fairly similar (and actually wider at 6 lanes instead of 4).
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Just wait for cost blowouts (which will of course be funded – it’s a road!) and the realisation that half the costs have been hidden by accounting in other projects, all so that this one has a nice BCR.
Exactly the cost blowouts will begin and be chalked up to unforseen complications, unforseen by the NZTA but no one else…
I’m quessing even NZTA forsees them. Victoria Park has a cost envelope blow out window of 100 million on a 350 million project. Whereas the new trains have a cost window of 0….
The cost blow out includes re-work however, which in most projects compromises of approximately 10-15% of the overall budget. Then there is the usual provision for product increases, and for unforseen circumstances that arise. However roading projects will not blow out as much as they used to. Now these big projects are run as Alliances which mean the contractor, consultant and NZTA all loose profit on the project if it goes over budget, so now there is more reason to meet the price, and time and quality.
So because of the Vic Park Alliance history I highly doubt that project will have a major blow-out.
It makes sense for the contractor be financially responsible for the work as without it there is no incentive to make the work on time and on budget etc. I also think we should have incentives to get the work done faster and to a higher standard. i.e. if they can finish the project before time, under budget and with a better quality outcome then they should be rewarded. Of course this would mean that the agency giving out the work will need to ensure that the tender process is accurate so a company doesn’t give a 4 year timeframe when they know it will only take 3 to get extra benefits.
The roadheader ‘NATM’ (New Austrian Tunnelling Method) type tunnelling option is likely to be where a lot of the saving is. This option requires a lot better understanding of the characteristics of the rock than a TBM option. This is because the NATM option involves using and augmenting the inherent strength of the existing rock. The TBM option involves installing a permanent thick concrete lining as the boring progresses. For the roadheader option this means that a very detailed understanding of the rock conditions is required before it can be accurately priced. This means not just the type and strength of rock, but the nature of the discontinuities (orientation, spacing, joint surface conditions) and groundwater.
The rock at Waterview is Waitemata Group (where it isn’t Basalt) which can be a very weak rock (you cant get much weaker before it is classed as a soil). The structure of the rock in Auckland is also generally quite complex. It is therefore no surprise to me that only after a detailed investigation, as well as the right expertise (remember we havent built many tunnels in NZ in the last 30 years), would anyone be prepared to back a roadheader option.
I am not trying to defend the number juggling, I am sure there was plenty of smoke and mirrors, as usual. But Waterview is by no means going to be a run-of-the-mill civil engineering project, and will be one of the most complex since the big hydro schemes of the seventies.
Thanks for the very useful insight there Matthew. I have heard that roadheaders are also pretty slow… so it may take quite some time for one to dig a 2.4 km tunnel?
Yes I think it is generally slower than a TBM, and the rate is potentially more variable. A TBM might be able to achieve 50m a day. In good ground you might get up to 25m a day with a road header, but it could slow to say 5m a day if a zone of very poor quality rock is encountered.
In a roadheader tunnel, it is a phased operation where the rock is excavated for a given length, then support is installed. If the rock is poor, the length that can be safely excavated at any one time without support will be reduced, and a lot more support will need to be installed.
Well, but contrary to a TBM method, where one of these things alone costs half your budget, you could run roadheaders in multiple different tunnels and from both directions, couldn’t you? So maybe the time delays wouldn’t be too bad.