KEY POINTS:
Railway workers started a fire yesterday at Mount White Bridge, south of Arthur's Pass in the Southern Alps.
At its peak the fire engulfed 70 hectares and was threatening to cross the Cass River but was brought under control yesterday, allowing State Highway 73 to be reopened.
Government-owned rail network operator Ontrack has accepted responsibility for starting the fire.
Ontrack spokesman Kevin Ramshaw said a track gang was doing track replacement work which included track cutting.
In dry conditions track workers cover the area near where they are working, but in this case there was a strong northwesterly wind blowing and sparks flew further than expected.
Ontrack did carry extra water but in this case there wasn't enough to deal with the situation and the fire got out of control.
The workers were safe, he said.
The site where the fire began is on the Midland Line, which crosses from Canterbury to the West Coast. Volume on the line is increasing due to higher coal exports.
- NZPA
