The preliminary report into the derailment of an XPT passenger train, at Wallan in February, has found it was travelling at more than 100kmh/hr, as it entered a passing loop.
The train driver and a worker were fatally injured in the derailment.
The preliminary Australian Transport Safety Bureau report found a 15km/speed limit had been imposed on the passing loop, which was being used to divert rail traffic from the main Sydney to Melbourne line.
The preliminary report confirmed that the train, which was travelling from Sydney to Melbourne with six crew, the pilot and 153 passengers onboard, entered the passing loop at more than 100km/hr.
"Earlier that afternoon, the points at either end of the Wallan loop had been changed from their 'normal' position to their 'reverse' position, which meant that rail traffic, in both directions, would be diverted from the main line into the loop track," ATSB Chief Commissioner Greg Hood said..
"A Train Notice reflected this change and also specified a 15 km/h speed limit for entry into the loop."
The train's data logger showed an emergency brake application was applied a short distance from the points before entering the passing loop.
"This slowed the train a small amount before it entered the turnout travelling at a speed in excess of 100 km/h.
"The train was not able to negotiate the turnout to the loop track at this speed and derailed."
All vehicles, except the rear power car, derailed.
During the derailment sequence, the lead power car rolled onto its left side and the XPT driver and the accompanying qualified worker sustained fatal injuries.
Three passengers were seriously injured and 36 received minor injuries, while five train crew who were in the passenger cars also sustained injuries.
Mr Hood said the preliminary report noted that due to damaged signalling equipment, a 24 km section of track between Kilmore East and Donnybrook, incorporating Wallan, was being managed by an 'alternative safe working system'.
The accompanying qualified worker boarded the lead power car near Kilmore and joined the driver as part of the alternative safeworking system.
"The continuing investigation will explore a range of factors, including a detailed examination of the alternative safeworking systems; the operation of the train; the conditions of the track and rolling stock; and crew and passenger survivability including a passenger survey," Mr Hood said.
The preliminary ATSB report details basic factual information established in the investigation's early evidence collection phase, including the sequence of events, track information, and data downloaded from the train's data logger.
"ATSB preliminary reports do not contain findings, identify contributing factors or outline safety issues and actions, which will be detailed in an investigation's final report," Mr Hood said.
The investigation is being led by Victoria's Chief Investigator, Transport Safety (CITS), under delegation from the ATSB, with support from the ATSB as well as New South Wales' Office of Transport Safety Investigations (OTSI).
Mr Hood noted an investigation of this nature and complexity might take more than 18 months to complete.
"However, should any safety-critical information be discovered at any time during the investigation, we will immediately notify operators and regulators, and make that publicly known," he said.
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