The New Zealand Transport Agency (NZTA) is warning drivers heading north of Auckland to expect "significant delays" after a haulage truck rolled on State Highway 1.
The truck has rolled on the highway south of Wellsford on Tuesday morning, leaving one person in a serious condition.
The northbound lane was blocked for several hours. Just after 10am NZTA tweeted that SH1 had been cleared, but delays would remain.
The Serious Crash Unit is investigating.