Safety issue

Safety issue description

There was no suitable assessment of the performance of sanders on the VLocity three-car set against defined acceptance criteria for improved braking performance in low adhesion conditions.
Issue number RO-2020-007-SI-03
Issue owner V/Line [The ATSB advises that this finding may be relevant to others involved in defining and assessing sander performance in low adhesion conditions]
Transport function Rail: Passenger - regional
Issue status Open – Safety action pending
Date issue released 28/10/2022
Issue status justification

To be advised

Safety action

Action type Recommendation
Action number RO-2020-007-SR-01
Organisation V/Line
Action description

V/Line advised the braking performance of the three-car VLocity trains were assessed for low adhesion conditions during the type testing qualification of the wheel slip/slide protection (WSP) system. The testing included operation of sanders where the wheel slip/slide protection system required sanding to occur. The test conditions were likely not as severe as those experienced by VL70 that seem to have been exceptional. V/Line advised that EN Standard 15595 (Railway Application Wheelslide Protection) did not include an acceptance criteria for the performance of sanders.

V/Line has also advised the ATSB of:

  • Completion of low adhesion testing on the standard gauge VLocity
  • Scheduled low adhesion testing of the broad gauge VLocity in the fourth quarter of 2022
  • Review of train braking performance since the introduction of intermediate car sanders, focusing on low adhesion conditions.

For the testing on the standard gauge VLocity trains, braking criteria in V/Line’s Signalling Principles were used as the assessment criteria for low adhesion conditions. V/Line has advised that any brake system design type testing will undertake similar testing principles.

V/Line has suggested that further wheelslide testing may be conducted focusing of an adhesion level of about 0.03. V/Line has also identified the potential for additional instrumentation during testing to assess initial adhesion levels and the improvement with sanding.
ATSB response

ATSB acknowledges the V/Line response that references that EN Standard 15595 (2018) did not include acceptance criteria for the performance of sanders. However, this safety issue specifically pertains to establishing appropriate criteria for assessing sander performance.

ATSB also acknowledges that the sanding system is part of a VLocity braking system that includes wheel slip/side protection as its primary system for managing braking in low adhesion conditions. However, assessment of the performance of a sander sub-system to defined criteria is considered integral to assuring whole-of-system braking performance in all environmental conditions that may be experienced on the Victorian network.

Safety recommendation to V/Line

The ATSB makes a formal safety recommendation, either during or at the end of an investigation, based on the level of risk associated with a safety issue and the extent of corrective action already undertaken. Rather than being prescriptive about the form of corrective action to be taken, the recommendation focuses on the safety issue of concern. It is a matter for the responsible organisation to assess the costs and benefits of any particular method of addressing a safety issue.

The Australian Transport Safety Bureau recommends that V/Line takes safety action to ensure the performance of sanders on the VLocity three-car set is assessed against defined acceptance criteria for improved braking performance in low adhesion conditions.
Action status Released