The NZ Herald yesterday reported the NZ Transport Agency now deems it not possible to strengthen the bridge a further time because the weight of the steel needed. NZ Herald photo
The NZ Herald yesterday reported the NZ Transport Agency now deems it not possible to strengthen the bridge a further time because the weight of the steel needed. NZ Herald photo
Yesterday's announcement the Auckland Harbour Bridge could no longer be "strengthened" is perhaps the final chapter in the cursed history of the city's infrastructure centrepiece.
The NZ Transport Agency says the weight of more steel to make the bridge stronger would compromise its "structural integrity".
Talk of traffic restrictions hasrenewed calls for an alternative harbour crossing to be prioritised to prevent the city from coming to a standstill.
From almost the moment it opened in 1959 - connecting the CBD to Northcote Pt on the North Shore - the original box truss four-lane structure was inadequate for Auckland's fast growing commuter numbers.
Over the next 50-odd years New Zealand's population grew from 2.8 million to 5 million - a third of that in Auckland.
But the eight lanes on the Auckland Harbour Bridge have stayed the same, and it's been a slightly shaky ride over the duration.
The latest steel crisis
The latest reminder of the fragility of the city's ageing harbour bridge came with yesterday's announcement that major maintenance on the bridge was no longer possible.
NZ Transport Agency said although the bridge had previously been strengthened several times, they would now need "active traffic management" to cope with the structural stress placed on it.
A November briefing paper to Transport Minister Michael Wood warned the "loading restrictions" would be needed within the next 20 years — but Waka Kotahi general transport service manager Brett Gliddon hints it may actually be much sooner.
Transport minister Michael Wood beside Prime Minister Jacinda Ardern. NZ Herald photograph by Mark Mitchell
Gliddon said active management of traffic on the bridge would not be needed within the next 12 to 18 months but did not elaborate further on a timeframe.
The revelations came at the annual review of Waka Kotahi New Zealand Transport Agency at a parliamentary select committee yesterday.
After a question from National MP Christopher Luxon, Gliddon said it was no longer possible to strengthen the bridge, which is crossed by 170,000 vehicles on weekdays.
"We believe we've strengthened it as much as we possibly can and we can't add more steel into it. It's counter-productive."
The NZ Herald yesterday reported the NZ Transport Agency now deems it not possible to strengthen the bridge a further time because the weight of the steel needed. NZ Herald photo
He said maintaining the "structural integrity of the bridge" could involve restricting heavy vehicles, limiting the lanes they could use, the number of heavy vehicles on the bridge at one time, or the time of day they cross.
Auckland's Chamber of Commerce chief executive Michael Barnett said it was costing "millions of dollars a day" as traffic is diverted because of strong winds on the bridge or roading needing to be fixed.
But Auckland mayor Phil Goff told the Herald that NZTA had told him proper maintenance of the bridge will continue to operate "indefinitely as a key strategic asset in the Auckland network".
A brand-new show for Vector Lights will tell the story of how Te Tiriti o Waitangi (the Treaty of Waitangi) on the harbour bridge. NZ Herald photo
This proper maintenance presumably does not extend to "strengthening", and Goff said traffic management had long been in the plans for the bridge.
"It has long been planned for heavy trucks at some point in the future to be required to use the centre lanes of the bridge rather than the so-called clip-on lanes," Goff said.
"The bridge will continue to be safe and suitable for general traffic, but at some point in the future, heavy trucks may need to use the centre lanes and not the clip-ons, or take the Western Ring Route at certain times to reduce pressure on the bridge."
Wood hinted yesterday heavyweight trucks may only be able to cross Auckland's ageing Harbour Bridge at restricted times of day.
NZTA's most recent design images for the Sky Path pedestrian bridge along Auckland Harbour Bridge. Photo supplied
"That would most likely mean, were it to occur, a conversation with that sector and looking at the hours of the day those vehicles most commonly access the bridge, which tends to be around 3 o'clock or 4 o'clock.
"What you can create is a reduction of the very heavy vehicles which, in the wrong circumstance, could create the heaviest risk of some kind."
The elusive SkyPath pedestrian crossing
Yesterday, Wood said the Government remains committed to the SkyPath despite Waka Kotahi saying no further weight should be added to the bridge for structural safety reasons.
The Transport Minister said in a couple of months a decision would be made on whether the design of the SkyPath would get the go-ahead from the Government.
It will be years before Auckland gets a new harbour croossing. Photo / Brett Phibbs
"We have to make sure this design is fit for purpose, that it delivers what we want and that it's also going to be safe and resilient," Wood said.
"There is very strong commitment from the Government to make sure Aucklanders have great walking and cycling access, including providing that access, across the Waitemata."
Since SkyPath was conceived 16 years ago, the project has been plagued by controversy, delays and rising costs.
In the past three years, the project has been taken over by NZTA from the SkyPath Trust and redesigned.
In February last year, the Government included SkyPath in a $6.8 billion New Zealand Upgrade Programme of transport projects and said construction would start early this year.
Wood said $360 million from the fund had been allocated to the SkyPath.
In January 2020, NZTA released images for the SkyPath project which has been renamed the Northern Pathway.
SkyPath was expected to cost $240m and $120m for a shared pathway extension to Esmonde Rd, rebranded the Northern Pathway by NZTA.
Wood said that money would not be redirected into fixing the bridge.
"That money is intended for a project which gets Aucklanders across the Waitemata by being able to walk or cycle. It's a critical gap," he said.
Bent strut causes traffic chaos
On September 18 a freak 127km/h gust of wind tipped two trucks on their sides, severely damaging a load-bearing steel strut in the middle of the bridge and causing traffic chaos.
The middle lanes of the bridge were out of action for weeks while a new strut was constructed and the broader Auckland network was brought to its knees as a consequence.
Engineers inspect the damaged strut on the Auckland Harbour Bridge. New Zealand Herald photograph by Luke Kirkness, 21 September 2020
Only 12 months earlier, a road-marking truck flipped and burst into flames on the bridge causing mayhem across the motorway system - and a political stoush between the main mayoral contenders at the time: Phil Goff and John Tamihere.
Tamihere's goliath multi-level bridge scheme
Auckland mayoral candidate John Tamihere is proposing to turn the existing Harbour Bridge into a two-level superstructure - with 10 lanes for cars on the lower level and four rail tracks and walkways and cycleways on the upper level.
Goff savaged the plan at the time - saying it would cost more than $10 billion to build and would "bankrupt the city".
On September 18 a freak 127km/h gust of wind tipped two trucks on their sides. Photo supplied
"A new 10-vehicle-lane harbour crossing, which will carry cars, rail, pedestrians and cyclists can be completed within six years on the existing bridge piers, replacing the existing bridge," Tamihere said.
"There will be minimal disruption to traffic. My team have looked at overseas structures and costs and it is very doable."
The now Māori Party chief of staff, claimed full or partial superstructure replacements have been carried out on a number of bridges in the United States, including the Milton-Madison bridge, costing US$104 million ($161m), over the Ohio River. It was built in 1929.
Last major harbour bridge restrengthening:
After engineers warned in 2007 of a potential for "catastrophic failure" in a worst-case scenario, 920 tonnes of extra steel was bolted and welded on to the clip-ons to extend the life of Auckland Harbour Bridge.
The Auckland Harbour Bridge that had a centre span damaged after a truck crash when a powerful gust of wind tipped it over. 20 September 2020 New Zealand Herald photograph by Dean Purcell.
At the time, restrictions were placed on heavy vehicles using the clip-ons to reduce vibration and help keep the bridge stable during welding of steel inside the box girders.
Today, the clip-on lanes are open to 50-tonne maximum permitted heavy vehicles and heavier vehicles can only use the truss bridge.
Second harbour crossing?
Ever since the Auckland Harbour Bridge opened in 1959, a second crossing has been mooted.
And in September last year that prospect was again pushed out to some hazy future date.
Goff said then that based on advice from Waka Kotahi and Auckland Transport that a new crossing will be needed after 2030.
Over the past 60 years, second harbour crossing schemes have included a new bridge, tunnels under the Waitematā Harbour, a rail crossing and a radical idea of demolishing the existing bridge for a new arching structure supporting a splay of cables in the shape of a sail.
There was a moment of anxiety in December 1958 as the rising wind slewed the floating spans. Photo supplied
The latest NZTA business case for a second crossing came in November last year, and determined a new $5 billion cross-harbour rail tunnel should be built within the next 20 years before any additional roading network.
The report projected that within 15 to 20 years a harbour rail tunnel from the city centre to Takapuna and Smales Farm would be required. A further $3 billion would be needed to extend the track from Smales Farm to Albany.
Transport experts did not believe a new road connection to ease congestion on the ageing Harbour Bridge would be needed until mid to late 2040 - 10 years after the rail tunnel.
The roading options would then be either expanding the capacity of the existing bridge or $10 billion for a road tunnel from the city centre to Esmonde Rd and additional motorway lanes to Constellation Drive.
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