The ATSB is highlighting the importance of train control systems (TCS) designers ensuring a system’s codes, procedures and programs, cover the functionality and performance requirements for all operational scenarios.
On 11 August 2016, track maintenance was planned in the vicinity of Ballarat Railway Station. To protect the work group, three sets of points within the work area were Blocked to prevent them being operated from the train control system (TCS).
Later that day, the points unexpectedly moved when the TCS was used to establish a route for a train to approach the area.
The investigation, carried out by the Victorian Office of the Chief Investigator, Transport Safety, on behalf of the ATSB under the Transport Safety Investigation Act 2003, found the design and coding of the TCS did not allow point Blocking-functionality for points that lay outside the selected route, but within its overlap area.
Victorian Chief Investigator, Transport Safety, Chris McKeown, said although maintenance crews are now required to isolate points equipment prior to carrying out maintenance, it is also important that TCS equipment correctly blocks field equipment according to the Train Controller’s settings.
“It’s important that those involved in the design and installation of these systems ensure that they adequately cover the functionality and performance requirements for all potential operational circumstances at any particular location.”
As a result of the incident, the TCS designers have improved their design procedures, and check and testing processes to ensure that Blocking is provided for overlap points. They have also tested and modified, where necessary, other similar TCS systems.
Read the investigation report, RO-2016-011: Signal control system irregularity, Ballarat, Victoria, 11 August 2016Last update 02 May 2018