Video: What a blast - Fiordland rock face blown to bits

The NZ Transport Agency says it is pleased with the first blast carried out yesterday as part of a programme to remove a 2000 tonne section of unstable rock above the western entrance of the Homer Tunnel.

This blast is part of a programme to demolish the rock which posed such a high risk to road users, that the NZ Transport Agency (NZTA) has closed the Milford Road from the eastern tunnel entrance since May 23.

NZTA Southland Area Manager Peter Robinson says a quick initial aerial inspection following the blast showed a substantial amount of rock came down, but with the light fading at the site it wasn't possible to take a close-up look.

An on-site inspection is planned for the next patch of clear weather, possibly on Monday.

"None of the tunnel infrastructure was damaged in the blast including a temporary portal extension that opened in February. This result has exceeded our expectations and it's a huge relief to get the amount of rock off mountainside that we did."

A total 2km exclusion zone including air space was in place around the blast site today, with road closures in place 5km on either side of the Homer Tunnel.