KiwiRail says it has taken steps to improve its train control safety systems after a critical report by the Transport Accident Investigation Commission.
The commission has several safety recommendations following a near collision in a Canterbury tunnel in 2011.
The commission says a coal train almost crashed head-on with a maintenance vehicle after a mentally stressed controller failed to make proper checks, so both would have been in the tunnel at the same time.
The train stopped just in time after a worker radioed an alarm.
The commission's recommendations include improved systems to manage high workloads for train controllers and to make sure they get proper rest, toilet and meal breaks.
KiwiRail chief executive Jim Quinn says safety is a prime consideration, but the incident was two-and-a-half years ago and improvements have already been made.
These include a system that makes trains electronically visible to controllers on 95% of its network, he says.