Ask Phoebe: Viaduct weakest link in motorway

The remodelled Newmarket Viaduct should last for more than 100 years. Photo / Greg Bowker

Q. Would you kindly refresh my understanding on why the original Newmarket Viaduct is being replaced so early in its life? Charles Goldie, Remuera.

A. There are several reasons. The 1966 viaduct was built to far lower earthquake standards than are now regarded as acceptable - being able to withstand, at most, only a one-in-500 year earthquake.

This makes the viaduct potentially the weakest point in Auckland's motorway network. In addition, the viaduct was not built to carry the traffic it now does (more than 200,000 vehicles a day), and the safety barriers are too low, allowing debris to fall on properties below.

Rebuilding the existing viaduct was not a realistic option because the structure does not allow for widening, and strengthening the cantilevered bridges would have lead to an increased life expectancy of only 40-50 years.

The new viaduct, which should last for more than 100 years, will be able to withstand an earthquake with a 2500-5000 year return period.

Q. Since the roundabout rules were changed, with more emphasis on signalling, many drivers are still signalling incorrectly.

On a daily basis, I notice drivers have their right indicator going as they approach the roundabout and still going as they exit, even when they are going straight through.

As I understand it, the road code says drivers should indicate right only when intending to exit at the third (or fourth, if there is one) exit, and, just before doing so, indicate left. Is this correct? Dave Batterbee, Northcross.

A. Nearly. The road code says if you are travelling more than half way round a roundabout, you should indicate right as you approach the roundabout, and indicate left as you pass the exit before the one you wish to take.

If you are going straight through a roundabout, do not signal as you approach, but indicate left as you pass the exit before the one you wish to take.

And if you are intending to take the first exit from the roundabout, you should indicate left as you approach the roundabout.

At some small roundabouts, a three-second warning of your intention is not always possible, but it is courteous to give as much warning as possible.

Q. Why has the clock on the tower on the Pernod Ricard building in the Viaduct been stuck on seven minutes to one for over a year?

Is it because Bayley's Real Estate is in the same building and the clock stopped when the real estate boom ended? Richard Harman, Auckland.

A. Pure coincidence, says Bayley's Property Services, who manage the building.

The clock mechanism was damaged last year during maintenance on other facilities in the building.

Three faces of the clock are now working, but the most public one, which overlooks Customs St, is still out of action.

The hands are the problem and finding replacement parts has taken longer than anticipated. The search continues.

The phone number to use when calling the Auckland Motorway Alliance is (09) 5200-200, not the number given on Tuesday.