A fire has damaged rail bridges and signals equipment on the Christchurch to Greymouth rail line.
The West Coast railway track remains closed, affecting TranzAlpine and freight services, while firefighters battle the blaze.
At 5pm yesterday, 10 helicopters fought the 300-hectare blaze near the Broken River viaduct, at the foothills inland from Springfield.
Then helicopters and ground crews continued to fight the blaze today, but it was under control.
Two railway bridges were in the path of fire.
KiwiRail network services manager Todd Moyle said the full extent of the damage would not be known until staff reached the site, which was unlikely to happen today.
Only then would they know when the track between Cass and Springfield would reopen.
A Department of Conservation hut, the Avoca Homestead, was evacuated yesterday afternoon and remained closed.
A fire spokesperson said two firefighting crews patrolled the area overnight, but withdrew after strong winds made it dangerous.