Significant lane closures would be in place on the Te Atatu motorway and there would be restricted access at the Te Atatu Interchange this weekend so the first section of the Te Atatu Road overbridge could be raised, Mr Gliddon said.
At Greville Road, the interchange was being upgraded and converted to one controlled by traffic signals.
Traffic volumes at Te Atatu would peak at abound 1700 vehicles per hour using the overbridge this weekend and around 4500 per hour using the motorway underneath, Mr Gliddon said.
"It's not possible to handle that volume of traffic during this weekend - there will be significant delays."
Motorists were advised to stay off the affected roads, or use alternative routes.
"If they do have to use the interchange, they must give themselves a lot more time to drive through it - traffic will not be flowing freely."
The Te Atatu overbridge was being raised 600mm (almost 2 feet) to improve safety by increasing the clearance for motorway traffic underneath, Mr Gliddon said.
The work was part of the Te Atatu Interchange Upgrade Project, one of six projects either to link the Northwestern and Southwestern (SH20) motorways and provide a motorway alternative to SH1 known as the Western Ring Route.
During the Greville Road off-ramp's weekend peak it was used by around 1600 vehicles an hour.
The work was part of a multi-million dollar upgrade of the city's entire motorway network, Mr Gliddon said.
"We do ask that people be patient this weekend and drive with care for their own safety and the safety of our contractors working on site.
"We will do everything we can to minimise disruption but the weekend is the only suitable time when this necessary work can be done."
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