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Post by kiwithrottlejockey on Jul 24, 2014 18:21:24 GMT 12
from Fairfax NZ — STUFF NATION....Is it time to tunnel across the Cook Strait?By GRANT MCLACHLAN | 3:30PM - Thursday, 24 July 2014 TUNNELLING THROUGH: Grant's vision for a possible fixed link
between Picton and Wellington ferry terminals, with different
levels for rail and road. — Image: GRANT McLACHAN.CONSIDERING the state of our inter-island fleet, the cancellations of air and sea travel due to weather and the future demands on utilities, it is time that we examine the feasibility of a fixed link between our two main islands.
Bridges and tunnel technology have improved in both engineering capability and affordability. More recently, this country has invested in megaprojects that have delivered on their goals.
“But what about the cost?” would be the cry by most. What we should be asking is: “What's the alternative?”.
Way back in the '90s, I considered that question in a research project. At that time, the English Channel Tunnel, the tunnel and bridge link between Denmark and Sweden, and several bridges and tunnels in Japan linking the main islands were ending construction. Since then, mega tunnels and bridges have been completed in Asia, America, and Europe.
Based on those projects, I have re-examined the feasibility of a fixed link between the North and South Islands of New Zealand.
The best comparison of the growth effect of a fixed link with the Cook Strait is the Confederation Bridge linking Prince Edward Island with New Brunswick in Canada.
Prince Edward Island has a population of 140,000 and New Brunswick has a population of 750,000. The Lower North Island of New Zealand has a population of 725,200 (Wellington and Manawatu) and the Upper South Island of 120,000 (Nelson, Marlborough, and North Canterbury).
Since the completion of the Confederation Bridge, tourist visits have increased from 740,000 in 1996 (the year before the bridge opened) to 1,200,000 in 1997 and stabilised at around 900,000 visitors annually. The bridge has daily traffic of approximately 4,000 vehicles. The toll for a two axle vehicle is C$44.50 plus C$7.25 per extra axle.
The Cook Strait ferry service carries about one million passengers and 230,000 vehicles annually. Between three and four million tonnes of cargo are transported on the ferries — two-thirds by truck and the other third by rail wagon. The revenue from sea traffic alone across the Cook Strait is over $1 billion annually.
A tunnel linking the Picton and Wellington ferry terminals would be 66.6km in length. Two bores would be drilled; a smaller pilot/maintenance/escape tunnel and a wider tunnel. The wider tunnel could have separate levels for road and rail traffic.
The Channel Tunnel cost £4,650 billion (two tunnels and a pilot, 1994) and the Seikan Tunnel cost ¥538.4 billion (US$3.6 billion, one tunnel and a pilot, 1988). The Seikan Tunnel has the most similar length and terrain to a Cook Strait Fixed Link.
Based on other similar projects, and considering how much traffic already crosses the Strait, that makes the feasibility of a tunnel very realistic, especially if the tunnel cost could be paid back within 15-20 years — shorter than the Auckland Harbour Bridge tolls were in place.
The government-owned Kiwirail is considering building a new and expensive ferry terminal while its fleet struggles to stay in one piece. Wellington Airport is also looking at extending its runway. The spoil from a tunnel could be used to extend the runway, expand port facilities, and reclaim other land.
“But what about the earthquake risk?” some would say. The Seikan Tunnel linking Hokkaido and Honshu islands in Japan sits in an area prone to earthquakes but has withstood many major earthquakes unscathed. The shortest and most practical route between Wellington and Picton ferry terminals would avoid the Tinakori fault and stay west of the continental fault.
Another factor to consider is the growth in demand for utilities. Currently, only electricity using the HVDC link is shared between islands. A tunnel would allow many more utilities to be shared between the islands.
Rather than dismissing the suggestion of a fixed link, we should at least explore whether it is possible and then whether it is feasible.• Grant is a former infrastructural analyst and independent hearings commissioner.www.stuff.co.nz/stuff-nation/assignments/share-your-news-and-views/10301361/Is-it-time-to-tunnel-across-the-Cook-Strait
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Post by Dave Homewood on Jul 24, 2014 18:40:16 GMT 12
Can't we incorporate the Kelly Tarlton's style of underwater tunnel and have a clear top so you can see the fishes as you drive through?
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Post by baronbeeza on Jul 24, 2014 19:26:04 GMT 12
A tunnel linking Picton terminal ?
Somehow I suspect the portal would be some distance from Picton, somewhere on the Cloudy Bay coastline would be more likely.
I was wondering about the seriousness of the article when he mentions linking the two ferry terminals..
I doubt we have the population, or traffic flow, to make such a venture viable in the near future. It is a nice dream for the years ahead all the same.
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Post by John L on Jul 24, 2014 19:54:35 GMT 12
A good idea, but, I would think the challenges produced by having a tunnel that could withstand the tectonic forces involved would be massive.
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Post by kiwithrottlejockey on Jul 24, 2014 20:32:39 GMT 12
At one time, most people thought the idea of a railway line linking Auckland and Wellington to be a delusion in the minds of raving lunatics.
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Post by Dave Homewood on Jul 24, 2014 20:45:39 GMT 12
Wikipedia says the narrowest point to point from North and South Islands is 22 kilometres, and the depth is an average of 128 metres. That would be a very long and deep tunnel. I think it would be better if they put on cheaper flights like the old days. It used to be standard $29 for Blenheim to Wellington when I lived at Woodbourne in 1989, by Friendship. Now it's a horrendous price, anywhere from $180 to $360 for about 20 minutes flying time!
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Post by DragonflyDH90 on Jul 24, 2014 21:05:31 GMT 12
As Jon L mentioned, this country is far to seismically volatile to have something like that. The number of fault lines in that area alone are huge and well known as some of the most active in the region. You wouldn't catch me in it.
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Post by beagle on Jul 24, 2014 21:06:11 GMT 12
why not lay the tunnel on top of the sea bed instead of boring under the sea bed.
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Post by obiwan27 on Jul 24, 2014 21:15:04 GMT 12
Wikipedia says the narrowest point to point from North and South Islands is 22 kilometres, and the depth is an average of 128 metres. That would be a very long and deep tunnel. I think it would be better if they put on cheaper flights like the old days. It used to be standard $29 for Blenheim to Wellington when I lived at Woodbourne in 1989, by Friendship. Now it's a horrendous price, anywhere from $180 to $360 for about 20 minutes flying time! Just had a look on the Air NZ website under the Grab a seat section. Blenheim to Wellington one way for $69 one way or $138.00 including gst and that's for one carry on bag. Not bad when you consider it was 25 years ago. I assume that's $29 one way? |
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Post by kiwithrottlejockey on Jul 24, 2014 21:27:42 GMT 12
As Jon L mentioned, this country is far to seismically volatile to have something like that. The number of fault lines in that area alone are huge and well known as some of the most active in the region. You wouldn't catch me in it. Every time I go to work, I drive trains through an 8.8km-long tunnel that has a fault-line crossing it a few kilometres in from either end. If the "big one" hit while I was inside that tunnel, it is feasible that I could suddenly find a solid rock wall in front of me, although I don't lose any sleep over that possibility. Then again, an aeroplane, or a meteorite could suddenly fall on me from a great height without warning, yet I don't lose any sleep over that possibility either. If my number is up, then shit happens. |
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Post by Dave Homewood on Jul 24, 2014 21:50:05 GMT 12
You miss the point there Ken. That was the standard fair. There were no discount fairs, no grab-a-sears (i.e. one or two seats in the plane load at %69 when the rest of the plane is paying an average of around $200). It was $29 for all the seats. The $29.00 deal was painted on the wall of the old Woodbourne terminal. It was pretty much like a bus fare. Now you have to book months in advance to get the slim chance "cheap" seat, but many on the same aircraft end up paying more than what it costs to fly to Aussie. It's pretty crazy.
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Post by Bruce on Jul 24, 2014 22:50:25 GMT 12
As this research project is essentially a Thought exercise using the model of the Channel tunnel and other overseas projects, I think that a lot more investigation would be required before anyone could say that it was feasible or not. The Channel Tunnel was excavated through a single continuous layer of chalk - a reasonably easily dug, yet stable and water resistant rock.One documentary I saw stated that the continuous chalk layer was the only reason the channel tunnel could be economically viable. I don't know what the seabed of Cook Strait is made up of, but I'd hazard a guess it is volcanic and fractured. If I recall my geography, the tectonic plates change the way they overlap and move in the region of Cook Strait, leaving fractures in the rock (Like bending Gib Board) that are porous and allow water through under high pressure from the sea above. Literally the difference between chalk and Cheese! I dont think you can mathematically extrapolate the costs of such a project based on overseas projects of a similar size. The devil is in the detail and that is where the costs can run away out of proportion. It could be technically possible to build such a tunnel - maybe using a mixture of sunk seabed sections and bored tunnel, but it will require extremely complex and expensive engineering solutions. The NZ economy has a long way to go before it can sustain that - especially with other, more important infrastructure spending (Including Christchurch earthquake recovery) due within the next 20 years. Given an unlimited budget, civil engineers could make it work, but that's not going to happen - and I'm not keen on working until I'm 85 to fund it.....
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