Ongoing bridge repairs for future traffic growth
The Auckland Harbour Bridge turns 50 this weekend during a multi-million dollar strengthening project and low-key anniversary celebrations.
The bridge opened at the end of May in 1959 after four years of construction.
Thousands crossed the bridge during its opening but the New Zealand Transport Agency has decided against an anniversary bridge walk.
Regional director for Northland and Auckland Wayne McDonald says he realises people will be disappointed they won’t be able to walk over the bridge for the celebrations.
“The NZTA’s decision was taken reluctantly and one of the main reasons behind it was the sheer number who would want to take part – a survey indicated up to 300,000 people – and our ability to safely manage them and the widespread disruption that would occur on roads through Auckland.”
NZTA chief executive Geoff Dangerfield says that the clip-ons are not a viable alternative for a bridge walk.
“They are more flexible than the truss [the central four lanes] and large numbers of people walking on them at the same time would cause significant movement and challenge our ability to ensure their safety.”
Heart of the City chief executive Alex Swney says he has mixed feelings about the bridge.
“It is wonderful that it has been here 50 years.”
But he says it is in a con- stant state of repair.
“We should celebrate what it has done. It’s a pity that in these difficult times we can’t have a celebration.
“Sydney-siders do it every New Year’s Eve, why can’t we do it once every 50 years?”
The $45 million strength- ening project will see more than 760 tonnes of steel added to the bridge’s box girders – the clip-on lanes – and when finished will cater for 10 to 20 years of future traffic growth.
Mr McDonald says the box girders have been closed up to six nights a week for cer- tain aspects of strengthening like welding, final torquing of bolts and surveying of existing components.
“Painting of the new steel sections will continue through into 2011, although repainting of the bridge is a continuous process.”
Up to 204,000 vehicles use the bridge daily.
Mr McDonald says work started on the northbound box girder in September last year and strengthening of the southbound box girder should commence by August.
“Over 300 tonnes of steel have now been fixed into place in the northbound box girder.”
In October 2007, it was reported that the clipons were at risk of “catastrophic failure” if heavy trucks were bumper to bumper in both lanes of each.
But the NZTA says the bridge has always been safe to use.
“If the NZTA thought motorists’ safety was at risk it would be closed immediately,” says Mr McDonald.
He says the upgrade is an essential part of ongoing maintenance for the bridge and about 100 workers are on site, some of who work by abseil.
Since mid-2007 the outer lanes on each side of the bridge have been closed to vehicles over 13 tonnes, but once the strengthening upgrade is complete, the lanes will be able to handle the weight.
“With regular monitoring and maintenance, and future implementation of load restrictions when necessary, the box girders may be in service for another 50 years or more.”
Under the bridge: Wayne McDonald of NZTA says all steel installation on the 50-year-old bridge should be complete by the second half of next year.