A police spokesman said a three-car pileup at about 3pm closed the Southern Motorway going southbound for about an hour.
All lanes were blocked but the scene was cleared and emergency services opened a lane by about 4pm.
A second crash, this time involving two vehicles near the Saddle Hill onramp, happened at about 4.50pm.
The second crash closed a lane of the southbound motorway and added more traffic woes to the already congested route.
Waka Kotahi NZTA advised motorists to take caution and to expect delays while travelling south.