Motorists and freight operators are strongly encouraged to avoid Auckland Harbour Bridge in the coming week after the structure was damaged on Friday.
Waka Kotahi NZ Transport Agency (NZTA) is urging commuters to plan their weekday travel accordingly as the city faces significant and ongoing disruption.
Four lanes of the Harbour Bridge are currently closed after two trucks - one northbound, one southbound - were blown over by 127kmh wind gusts on Friday, causing damage to the bridge's structure.
A central strut - integral to supporting the weight of the bridge - now needs replacing, a process that could take more than five weeks.
The Harbour Bridge is the primary infrastructure connecting Auckland's central, eastern and southern suburbs to the North Shore and New Zealand's northern regions, crossing the Waitematā Harbour.
With more vehicles opting for the western ring route via Greenhithe and State Highways 16, 18 and 20 to avoid ongoing congestion, NZTA is asking commuters to consider working remotely.
"We ask people to consider working from home if possible or using public transport instead of taking the car. If you must travel, avoid peak times in the morning and evening, and allow extra time for your journey," senior journey manager Neil Walker said in a statement on Sunday.
"Heavy congestion and delays are expected on both sides of the bridge as well as other state highways and local roads."
Walker reiterated that although a temporary fix to reopen the lanes may be possible in the coming days, a permanent repair is still weeks away.
The NZTA urges those who must travel - particularly heavy and freight vehicles - to opt for the western ring route. The Northern Busway is still operational and buses are safe to use the open north and southbound clip-on lanes. However, commuters using public transport will face delays as buses join the queues to cross the Harbour Bridge, and are advised to allow extra time for their journey.
"Waka Kotahi is focused on doing everything possible to re-open the centre lanes of the Harbour Bridge as quickly as possible however they will potentially remain closed for a number of weeks," Walker said.
A team of nine structural engineers is currently working on removing and replacing the 4-tonne strut, including modelling how to re-balance its load-bearing function so it's safe to incrementally reopen lanes in the centre span with a temporary fix in place, the NZTA said.
"This work is ongoing and will take time. Fabrication of the replacement parts for the temporary and permanent fixes is also underway."
Engineers have undertaken safety assessments over the weekend, with the sheared end of the damaged strut being temporarily bolted back on the bridge.
NZTA confirmed there is no risk to the overall safety or structural integrity of the Harbour Bridge, and the clip-on lanes are safe to use as they have a supporting structure.
More than 170,000 vehicles, on average, cross the Harbour Bridge on weekdays, with the configuration of the eight lanes changed four times each day to adjust to peak time traffic flows.
As of early Sunday afternoon there is some congestion across the bridge and into the CBD, according to data from Google Maps. A journey from Auckland's North Shore to the city centre may take up to 10 minutes longer than usual.