Manawatu Gorge closed. Again.

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Geektastic

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#216671 7-Jul-2017 11:09

FYI in case anyone wasn't aware. From the NZH

"A significant highway has been closed indefinitely by the threat of massive rock slips.

The NZ Transport Agency said this morning new geotechnical information has highlighted major safety risks in the Manawatu Gorge which are likely to keep the road closed for some time.

The State Highway 3 link from Hawke's Bay-Wairarapa to Manawatu and State Highway 1 on the southern side of the gorge, which separates the Tararua and Ruahine ranges, closed on April 24 because of a slip.

A release from NZTA said an urgent programme of additional work will get underway immediately to significantly improve the alternative Saddle Road route.

Regional transport system manager Ross I'Anson said a significant amount of work has been undertaken in the gorge to clear the slips which have come down since April, but geotechnical engineers have now confirmed that a large area above the Kerry's Wall rock face is highly unstable, with an imminent risk of further significant slips or rockfalls.

"Geotechnical assessments have confirmed that the entire hillside is moving, and the rate of that movement is accelerating. That's an indication that a slip as large or larger than the 2011 slip which closed the road for 14 months could come down at any time."

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#1814305 7-Jul-2017 11:28

I think its time to find a permanent alternative and close it permanently. The Saddle and Pahiatua Tack are OK but not up to the volume or heavy trucks.

WyleECoyoteNZ

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#1814307 7-Jul-2017 11:29

The answer\solution isn't cheap whatever way you look at it.

Either requires a tunnel the entire length or

A open tunnel you see in the like of the swiss alps, the big concrete things that are open on the outside, something like this

Geektastic

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#1814311 7-Jul-2017 11:40

WyleECoyoteNZ:

The answer\solution isn't cheap whatever way you look at it.

Either requires a tunnel the entire length or

A open tunnel you see in the like of the swiss alps, the big concrete things that are open on the outside, something like this

Rock/Snow fall protection. Yes. However you do need to be sure that the ground underneath the road and to which the rock tunnel is attached won't slide away beneath you. As long as the risk is all above you then that should work.

I can't see anything happening. It'll just continue to be another pinch point on the road network, like the Rimutaka Hill and we'll continue spending money on things like sailing events instead.

I'd cheerfully see a toll tunnel there (a common overseas solution) for which I would happily pay $10 each way if it was quick and unaffected by geology so regularly.

vexxxboy

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#1814313 7-Jul-2017 11:43

remember crossing the gorge in the 70's, no barriers on the sides, one lane most of way because of slips and work being done , i thought it was exciting , my father hated it lol

Common sense is not as common as you think.

MikeB4

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#1814315 7-Jul-2017 11:44

Geektastic:

WyleECoyoteNZ:

The answer\solution isn't cheap whatever way you look at it.

Either requires a tunnel the entire length or

A open tunnel you see in the like of the swiss alps, the big concrete things that are open on the outside, something like this

Rock/Snow fall protection. Yes. However you do need to be sure that the ground underneath the road and to which the rock tunnel is attached won't slide away beneath you. As long as the risk is all above you then that should work.

I can't see anything happening. It'll just continue to be another pinch point on the road network, like the Rimutaka Hill and we'll continue spending money on things like sailing events instead.

I'd cheerfully see a toll tunnel there (a common overseas solution) for which I would happily pay $10 each way if it was quick and unaffected by geology so regularly.

The Rimutaka Road is a odd one, a few years back a survey was taken of the Wairarapa locals and the majority did not want a tunnel as they felt it would change the Wairarapa and it would lose its unique character.

MikeB4

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#1814317 7-Jul-2017 11:45

vexxxboy:

remember crossing the gorge in the 70's, no barriers on the sides, one lane most of way because of slips and work being done , i thought it was exciting , my father hated it lol

yep remember that, even now (until it closed) I felt like I was running a gauntlet every time I drove through there.

Ge0rge

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#1814318 7-Jul-2017 11:46

There is a very similar solution through the Arthur's pass - overhead rock protection in some places, and a viaduct that puts the road out of harms way - I wonder if they could replicate that through the gorge?

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frankv

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#1814320 7-Jul-2017 11:54

Another alternative is to do what they did in Arthurs Pass (and what legend has it the US Army wanted to do during WW2)... build essentially a "bridge" down the length of the gorge, out in the middle of it somewhat, so that any slips go underneath the bridge.

Maybe they should look at closing the railway on the North side of the gorge and putting the road there? That would be cheaper than building a new road alongside the railway. My understanding is that the North side of the Gorge is different geology from the South; the North side is solid rock, whereas the South is crumbly and broken.

Or they could do what they do in Switzerland... drive cars onto flatbed railway wagons, to be pulled through the Gorge in a train. Could have loading/unloading ramps at Woodville and Ashhurst so the rail journey would be short and could be run often.

DarthKermit

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#1814359 7-Jul-2017 13:06

Cost of a tunnel to bypass the gorge is conservatively estimated at $1.8 billion. That's more than the cost of the entire waterview connection in Auckland, which was $1.4 billion.

I measured it and the shortest point to point route under the Tararuas (adjacent to the gorge) is 5.0 km. That would be going into the ranges just after where SH3 joins SH57 and coming out about where the existing bridge crosses the Manawatu river at the Woodville end. That's assuming the geological conditions at that area are even suitable for a tunnel.

The waterview tunnels are now the longest road tunnels in NZ (at 2.5 km long).

Geektastic

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#1815620 7-Jul-2017 18:29

MikeB4:

Geektastic:

WyleECoyoteNZ:

The answer\solution isn't cheap whatever way you look at it.

Either requires a tunnel the entire length or

A open tunnel you see in the like of the swiss alps, the big concrete things that are open on the outside, something like this

Rock/Snow fall protection. Yes. However you do need to be sure that the ground underneath the road and to which the rock tunnel is attached won't slide away beneath you. As long as the risk is all above you then that should work.

I can't see anything happening. It'll just continue to be another pinch point on the road network, like the Rimutaka Hill and we'll continue spending money on things like sailing events instead.

I'd cheerfully see a toll tunnel there (a common overseas solution) for which I would happily pay $10 each way if it was quick and unaffected by geology so regularly.

The Rimutaka Road is a odd one, a few years back a survey was taken of the Wairarapa locals and the majority did not want a tunnel as they felt it would change the Wairarapa and it would lose its unique character.

Yes. That's a very valid reason for hamstringing one of your national highways. Parochial f***wits!

DarthKermit

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#1815622 7-Jul-2017 18:36

BTW, those stories of what the Yanks proposed to do transport wise during WW2 appear to be all urban myths. There are three versions of the story that I've heard being bandied around: a bridge all the way up the gorge straddling the river, a different road over the top, a tunnel.

mattwnz

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#1815625 7-Jul-2017 18:39

Weren't the yanks also going to build transmission gully. At least that one is actually being built, which is a huge achievement considering all the delays.

DarthKermit

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#1815630 7-Jul-2017 18:49

This is where the current big slip has occurred. Google street view , just to the right of the gabion rock wall. There was a big slip in 1995 that closed the gorge for about ten weeks. They built that wall there to stabalise it.

blakamin

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#1815654 7-Jul-2017 19:39

DarthKermit:

This is where the current big slip has occurred. Google street view , just to the right of the gabion rock wall. There was a big slip in 1995 that closed the gorge for about ten weeks. They built that wall there to stabalise it.

Only 10 weeks?? ;p

I hated the closure in 2011(?).

Had to go via Rimutaka or Saddle Rd.. Totally sucked in a truck at 3am in winter, and even worse coming back in winter and traffic.

DarthKermit

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#1815659 7-Jul-2017 19:45

Yeah I bet. I've never been over the Rimutaka hill road, but I've seen it on google street view. It's as twisty as hell.

Almost all of the Saddle road has been widened now. It's not up to full state highway standards, but maybe it could be made so if the gorge is a goner.

In a 100 or even a 1000 years, no doubt the gorge will still be slipping away. It's just the nature of the crumbly rocks there.

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