The NZ Transport Agency (NZTA) is delighted to report the achievement of a major milestone in its $215M Newmarket Connection: 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 yesterday evening. 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.
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.”
Following this initial deconstruction activity, 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, Stage 2 of the Newmarket Connection: Viaduct Replacement Project, 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.