Photo by Stephen Jaquiery.
A Fire Service spokesman said emergency services responded just after 6am.
The truck was carrying freight, including 200kg of fireworks.
They did not pose a danger, he said.
The road was closed for time to allow a a crane to right the trailer. It reopened about noon, a police spokesman in Wellington said.
A St John spokeswoman said an ambulance attended but no-one was injured.
