The NZTA's acting state highway manager for Waikato, Michelle Te Wharau, said: ``Today's events are a terrible tragedy, and our deepest sympathies go out to the family and friends of the victim,''
She said SH3 was monitored regularly for rock fall activity because the topography and the geological landscape made it prone to instability.
The agency had geotechnical assessors at the site to assess the state of the rockface and it aimed to reopen the road to a single lane this weekend.
In the meantime it would remain closed until it was confident the cliff face had been stabilised and detours were in place.
The NZTA supported recommendations from police for drivers to avoid unnecessary travel between New Plymouth and Te Kuiti until the section of road fully reopened.