It could take longer than five weeks to permanently fix damage caused to the Auckland Harbour Bridge by one of Friday's truck crashes.
There were two truck crashes on Friday when wind went from gusting at about 60kph to 127kph suddenly. A medium-sized truck was thrown onto its side, toppling onto a median barrier and blocking several centre lanes for hours before it could be safely removed. At the same time, a southbound truck was blown onto a tilt, hitting the bridge's structure before righting itself.
A central strut was damaged and now needs to be replaced.
"While it used to carry load to hold the bridge up, it no longer was. That load then redistributed itself through the bridge," New Zealand Transport Agency (NZTA) general manager transport services, Brett Gliddon, told media on Saturday.
Gliddon said that while there is no risk of the bridge collapsing, it's not appropriate for vehicles to be travelling across the central bridge. That leaves two lanes heading northbound and two lanes southbound on the bridge's outer clip-ons.
He said a new strut would need to be manufactured and be put into place.
That permanent solution could be several weeks away, Gliddon said.
"I would expect it could be four to five. It may be longer," he said. "It's not days."
Engineers are currently assessing the damage to the bridge to see if there could be a temporary solution. If that's possible, some of the central lanes could be opened for light vehicles. But there is no guarantee of that and it could still be a week away.
Gliddon said because the load has redistributed on the bridge, engineers would check there was no additional damage on any other struts.
Gliddon said in the meantime, while the bridge is operating at half capacity, motorists should look for alternative transport routes and options, like public transport. The city's Western Ring Route - which goes around the harbour - had been built for a situation like this. If people can work at home, they should do that, he said.
The truck crashes and resulting damage has caused traffic chaos on Saturday, with some people complaining of delays of more than an hour.
"Obviously, with half of the capacity out of the bridge, the rest of the network will see some congestion. So people are going to have to be prepared for that and manage their travel accordingly," Gliddon said.
He described the strut as a "pretty big piece of metal" and because each part of the bridge is unique, it wasn't feasible to have a spare replacement for each piece.
"It goes from the road level of the bridge right up to the top of the bridge. It is pretty big in diameter, so it would be 400 or 500mm square and it is obviously bolted at the bottom with a big steel plate and bolted at the top. We have got 15-20 bolts holding it in place.
"We haven't had a structure on the bridge hit like this before."
Gliddon said it was safe for heavy vehicles to use the clip-ons, but they would be encouraged to use the Western Ring Route.
On average, more than 170,000 vehicles cross the bridge on weekdays. NZTA says it has been working on a possible second harbour crossing.
"This incident has shown you do need capacity in the network to manage events like this because even though they are low-probability, they are high-consequence type events," Gliddon said.
The National Party announced in July that it wanted work to begin on a second harbour crossing - likely a rail and road tunnel under the harbour - in 2028.