KEY POINTS:
I understand that one extra lane is to be added to the Newmarket Viaduct, and that to do this the entire structure must be demolished and rebuilt. Why, just to add one lane? Is it possible that the viaduct has defects, is unsafe, and must be replaced? John Smith, Auckland.
It's not so much that the 1966 viaduct has defects, as that its rating to withstand only a one-in-500-years magnitude earthquake makes it seismologically vulnerable.
Transit's website warns that parts of the viaduct could collapse in just a "reasonably moderate earthquake", making it unacceptably risky by international standards. So in that sense, yes, it is unsafe.
Strengthening the present structure is possible, just, but it would still leave the viaduct vulnerable in some areas, and it would be almost as expensive as a new one.
Construction of the new viaduct, to be built 13m to the east of the present one, will start with four new southbound lanes, followed by the demolition of the existing three southbound lanes. These will be replaced in the same spot by three new northbound lanes, allowing the rest of the old structure to be taken down. The new viaduct will be designed to withstand a one-in-2500-years quake.
The original date for construction to begin was 2009 but this has been brought forward and may start as early as December.
A highly desirable outcome, of course, would be completion in time for the 2011 Rugby World Cup.
Can you tell me if there is a plan to widen the bridge on St Lukes Rd over the railway, or introduce two lanes from New North Rd to Great North Rd? This would give two lanes all the way from Greenlane to Western Springs. Neil Heath, Auckland.
There are no plans for double-laning here. There would be the cost of land acquisition to take into account, and the council feels that the situation works quite well as it is, with the present level of traffic.
* Do you have queries about public transport, roading projects, roadworks or how to get a driver's licence? Contact Phoebe Falconer at Get Moving, Editorial department, NZ Herald, PO Box 32, Auckland. Fax (09) 373-6421 or email newsdesk@nzherald.co.nz. Include name and address.
