Motorists are being warned to take care on Auckland roads tonight, as heavy rain gets ready to strike the city.
The New Zealand Transport Agency has issued a warning for drivers to be safe and drive to the conditions.
Heavy rain is expected to lash areas of Auckland from 11pm.
MetService meteorologists said there was a chance the rain could stall over the city for a few hours.
Rain could reach warning criteria in localised areas of Northland, Auckland, Coromandel and the Bay of Plenty and further heavy rain was possible tomorrow as a front moves back through the regions, MetService said.
Earlier, the New Zealand Transport Agency said southbound traffic was now flowing from Drury following the crashes.
"Thanks for your patience," the agency tweeted.
A southbound vehicle towing a trailer crashed just north of the Arimu overbridge in Papakura, South Auckland, shortly before 3pm.
It caused traffic to back up to the Drury off-ramp - adding to the already packed motorway after a two-car collision blocked three southbound lanes near the Khyber Pass on-ramp about 1pm.
One patient was taken to hospital in a moderate condition by St John.Police described the traffic as "very heavy" this afternoon and warned the public to expect delays.