The NZ Transport Agency has begun removing the original northbound Newmarket viaduct on Auckland's Southern Motorway (State Highway 1) - the last of four stages of work to replace the viaduct on the busiest section of highway on the city's motorway network.
Deconstruction of the 46-year-old viaduct has started at the Gillies Avenue bridge at the northern end of the viaduct.
It has been a symbolic entrance to central Auckland for people driving north on the Southern Motorway since it opened in 1966.
"It has served Auckland well for almost half a century, but its replacement is much better designed to meet the increasing demands of a growing city," says the NZTA's State Highways Manager for Auckland and Northland, Tommy Parker.
The old northbound viaduct was constructed with 223 concrete segments, each weighing between 60 and 110 tonnes. The blue gantry will work its way southwards towards St Marks Road, lowering the concrete segments as it goes during the next six months. The segments will be transported away from the site where they will be processed and their parts recycled.
Despite the technically challenging project, the NZTA and its project partners (Leightons, Fulton Hogan, Boffa Miskell, URS, VSL, BECA and Tonkin & Taylor) have been constructing a replacement viaduct and deconstructing (removing) the old one beside a section of motorway that carries on average 160,000 vehicles a day.
"We've been able to do that because of the good support we have had from drivers," says Mr Parker. "Drivers are travelling through a live construction zone and sometimes there's little more than a metre separating our workers and motorway traffic.
"Reducing the speed limit of 70kph was the key in allowing us to keep the motorway open at virtually full capacity throughout the replacement process. Driving conditions are more challenging with the motorway lanes temporarily narrowed across the viaduct. The job's not quite done, and we urge all drivers to continue to observe the lower speed limit for their own safety, the safety of their passengers, and the safety of construction workers."
The Newmarket Viaduct Replacement Project has replaced the old viaduct with its three lanes of northbound and southbound traffic. The new viaduct 20 metres above Newmarket is wider and stronger, and has three lanes northbound and four lanes southbound. It is designed to withstand a 1 in 2,500 year seismic event.
The new southbound viaduct, the first stage of the project, was opened in 2010. The old southbound viaduct was then removed and the new northbound one constructed in its place and opened last January. The full project is due to be completed this December.
For more information on the Newmarket Viaduct Replacement Project, visit www.nzta.govt.nz/newmarketconnection(external link).