The combination of a wiring error and deterioration of insulation resistance in an uncouple solenoid connector lead to the uncoupling of a suburban passenger train travelling from Flinders Street to Lillydale Station, a new ATSB investigation report says.
Shortly after leaving Croydon Station, the two 3-car train set uncoupled at its mid-point while on a left hand curve, about 800 m from the station. About half way through the curve the driver noticed the train had uncoupled with the trailing 3-car set detatching from the train. The train, with 150 passengers on board, was travelling at about 78 km/h when it uncoupled with the trailing car set travelling under emergency braking for nearly 200 m before coming to a stop. There were no injuries to passengers or crew.
The investigation, conducted on behalf of the ATSB by Victoria’s Chief Inspector, Transport Safety, found an undetected wiring error from a modification to the wiring of the low-note whistle of the lead car of the train combined with a deterioration of insulation resistance in the uncouple solenoid resulted in a error circuit forming to energise and trigger the uncoupling.
The ATSB safety message from this investigation highlights the importance of ensuring a verification program is incorporated into quality assurance systems to mitigate the risk of errors during installation and modification of electrical systems.
This investigation highlights the importance of ensuring a verification program is incorporated into quality assurance systems to migitate the risk of errors during installation and modification of electrical systems
A function test alone would not have revealed the wiring error; an assurance program involving a secondary and independent check of the wiring modification may have been the only means of detecting the error, the investigation notes.
Following the incident Metro Trains Melbourne inspected found 11 car-sets with low-notes whistles wired incorrectly and rectified the error.
The ATSB welcomes the updates to the Metro Trains Melbourne’s low-note whistling documentation to prevent further wiring errors and the addition of an independent check of any future wiring work in the form of a supervisor check.
Read the report: Parting of Metro Trains Melbourne passenger train TD 3817, at Croydon, Victoria, on 9 November 2018