The Transport Agency says work on removing a 2000-tonne section of unstable rock above the Fiordland's Homer Tunnel is going well, but it is too soon to say when the road will reopen.
The Milford Road, from the eastern entrance, has been closed since 23 May for emergency safety work.
The agency's Southland manager, Peter Robinson, says a blast over the tunnel's western entrance on Friday brought down a substantial amount of rock, but with the light fading, only a quick aerial inspection was possible.
He says a site visit for a close up look is planned for the next patch of clear weather, possibly on Monday.