"We know the woman left Benneydale in her car bound for Mangakino between 10pm and 10.30pm and she has sadly failed to make her destination."
There were no other occupants in the vehicle and no other vehicles involved, a northern ambulance communications spokeswoman said.
SH30 reopened to single lane traffic at 7am.
"Traffic management is in place, however motorists are advised to avoid the area where possible and if unable to, to expect delays," said Mr Friend.
The death brings the road toll this year to 133, compared to 144 at the same time last year.
It was the 125th fatal crash this year, compared to 121 at the same time a year ago, Ministry of Transport figures show.