The NZ Transport Agency said contractors were on site and one lane was opened at 4pm under stop/go management.
Toppled tree blocks State Highway 1
A tree is blocking State Highway 1 north of Auckland.
The fallen tree is causing delays at the Top Of The Dome, between Warkworth and Wellsford, the New Zealand Transport Agency (NZTA) said.
A spokesman said one lane was opened at 4pm under stop/go traffic management.
Earlier, the agency tweeted warning motorists to expect delays.
"Please follow directions of emergency services. Delays in the area are likely."