A mistake by a controller sent a freight train onto a track that was blocked by a crane, forcing the train to make an emergency stop, an investigation has found.
The Transport Accident Investigation Commission report into the November 2011 incident said that at the time there was major infrastructure and maintenance work underway on a section of track between Papakura and Westfield in South Auckland.
As a result, the northbound track was closed and a controller in the national train control centre in Wellington was managing the flow of trains through the work area, using the southbound track.
Metropolitan passenger train services had been cancelled to relieve congestion through the work area, but freight trains were still running.
About 11am a freight train was travelling north on the southbound track, a process called "wrong-line-running".
The report said the train controller mistakenly set the route for the train to cross back over to the northbound track too early, at Wiri Junction. The train driver did not question the train controller on the apparent change in plan.
Around the corner from Wiri Junction, a mobile crane was straddling the northbound track as it worked on removing a pedestrian overbridge. The train crossed over to the closed northbound track, and as it rounded the corner the driver saw the crane blocking the track ahead. He immediately applied the brakes and stopped his train 97 metres from the crane.
The report said the train controller was supposed to have applied "control blocking" to all signals or points where trains could potentially enter the closed work area, but he did not do this. Control blocking the signals and points prevents the train controller inadvertently setting the wrong route for a train to enter the work area.
The commission's report, released today, said it could not identify why the train controller made the errors. However, it said safety-critical systems should be safeguarded against one person's error resulting in an incident or an accident.
The commission identified three safety issues that either contributed to, or could have prevented, the incident.
Firstly, KiwiRail rules did not require a cross-check confirmation that appropriate control blocking had been applied to protect the section of track closed for maintenance work. The second issue was that the train driver was reluctant to, and did not, challenge the train controller when he was given an instruction that he thought was not correct. Thirdly, the information provided in special work bulletins was not clear.
The report said KiwiRail immediately addressed the first safety issue, while the other recommendations were awaiting the completion of corrective actions from the NZ Transport Agency and KiwiRail.
The commission said key safety lessons arising from the incident included that rail work areas must be fully protected from all other rail activities before work begins, and there must be a positive confirmation between train controllers and people in charge of work areas that appropriate protections have been put in place.
It also said all rail staff must communicate properly and be prepared to challenge other staff, including their superiors, if the plan was not proceeding as they understood it should.
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