Subscribe to RSSNewmarket Viaduct Milestone
A milestone in the $215n Newmarket Viaduct replacement project, with the successful removal of the first segment from the old Newmarket Viaduct.
The 70 tonne segment was lowered onto a specially constructed platform near the southern abutment last night. The operation follows the separation and stabilisation of the north and southbound lanes of the old structure, and two nights of concrete cutting during which the segment was safely isolated from the old structure using a diamond wire saw.
The Big Blue gantry will soon swing back into action, starting at the northern end of the viaduct. In a reverse of the balanced cantilever construction sequence employed in constructing the new viaduct, the gantry will remove segments evenly from the mid-span point between the old columns, working progressively inwards.
To prepare for the deconstruction, a network of over 1200 tonnes of steel brackets and tubular supports has already been installed underneath the old viaduct. These not only serve to stabilise and seismically reinforce the two halves of the old structure through the deconstruction process, but accommodate the extra weight of the 800-plus tonne gantry.
Once removed from the old viaduct, the old viaduct segments will be transported from site, crushed and recycled as part of the project’s “Zero to Landfill” policy. Opportunities for using the concrete recycled from the viaduct have already been identified at NZTA projects on the Western Ring Route.
NZTA’s Auckland State Highways Manager, Tommy Parker, says the successful operation augurs well for the delivery team as it tackles the most complex stage of the project with world-first engineering techniques to minimise disruption to motorists and the surrounding community.
“There is simply no global precedent for the staged removal of a bridge of this size or structure within such a tight environment and between the fast lanes of two carriageways of motorway traffic,” says Mr Parker. “This methodology represents a highly innovative response to the challenge of keeping the country’s busiest stretch of motorway open throughout a vital infrastructure upgrade.”
However, the challenge of keeping the motorway safely open also demands an appropriate response from the city’s motorists, says Mr Parker.
“As we head not only into this most complex stage of the Newmarket Connection project, but also the holiday season, I’d like to remind all drivers of the role they must play to ensure the safety of themselves, fellow drivers and indeed our workers. Only by all drivers observing the reduced 70 km/h speed limits can we continue to keep the motorway safely open at near full capacity in both directions throughout the replacement process.”
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5 Comments
Could some one please tell me why the bridge/fly-over has to go?
Is it life expired, if so was it poorly designed/build?
Cheers
It was one of the first of it’s kind, and not up to earthquake standards. I’ve also heard it has issues with heat expansion that have degraded the life of the structure considerably, due to an initial design flaw.
The basically worked out it would be cheaper to demolish it and start again than retrofit the existing structure.
I think the heat issue was why it also had to have a special and expensive surface treatment so there were higher maintenance costs which helped to increase the case for replacing it.
Also, the decision was made that they wanted another lane southbound (the first time I read an NZTA report admitting that the induced demand will soon clog up the new lane, btw). Even the northbound is built so they can add another lane there too - even though they’d have to basically quarry away the hillside under Auckland Grammar.
The replacement was needed, and NZTA can’t be faulted for it (unless you’d be willing to fault them for design decisions made 50 years ago). The fact that they bundled it with another motorway widening project going as far down as Greenlane, that certainly can be criticised. That space is now lost for other transport modes, such as triple-tracking rail. Fighting obesity by letting out your belt, anyone?
I think if we fast-pace the work of the new Auckland system, e.g. CBD loop and Airport link frequent services etc. the vaduct section might actually decrease in the amount of cars travelling through.