A late addition to a signal team's daily work plan, unnecessary complexity, and insufficient inspection and testing contributed to a freight train travelling through a busy Adelaide level crossing without boom gates active, an ATSB investigation has found.
During trackwork as part of the electrification of Adelaide's Gawler rail line, a subcontracted signal team was tasked with temporary alterations at a number of level crossings, including the installation of jumper cables to ensure protections - boom gates and lights - still activated when required.
Midway through the day on 7 December 2020, having already actioned work on two planned level crossings, the signal team was asked to perform work at the Torrens Road crossing.
"This was an unplanned addition to what was discussed in the pre-work briefing that day, placing additional demands on the signal team with short notice," ATSB Director Transport Safety Kerri Hughes said.
"Notably, the required work at Torrens Road also included two superfluous temporary jumper wires, unnecessarily increasing the complexity of the task and placing further work demand on the signal team, who then inadvertently installed one end of a jumper wire into the incorrect terminal."
Testing did not identify the error and this, combined with other signal works, meant the boom gates and warning lights did not activate when a containerised freight train travelled towards the level crossing a short time later.
"The freight train's driver saw the boom gates still open, and traffic on the road ahead, but was unable to stop the train before entering the level crossing, only narrowly missing a number of road vehicles," Ms Hughes said.
In addition to the factors which contributed to the incorrect installation of the jumper cable, the ATSB's final report also notes the methodology adopted by the signal team when implementing the Torrens Road inspection and test plan did not ensure independence between the installation and verification tasks.
"This resulted in the wiring error not being corrected and remaining in the control circuit, potentially affecting the correct operation of the level crossing warning equipment," Ms Hughes said.
In response to the incident, the principal contractor for the Gawler Rail Electrification Project, Acciona, undertook a risk assessment of the level crossing alteration works in consultation with the project stakeholders.
This resulted in new controls being incorporated into the work method.
"These controls include the potential for road closures when wiring alterations are required to facilitate trackwork," Ms Hughes said.
In addition to the specific factors contributing to the incident, the ATSB's investigation found the South Australian Passenger Transport Authority approved a package of inspection and test plan procedures that did not specify any requirement for testing to verify and validate the safety integrity of the altered level crossing control circuits.
"The effectiveness of any testing undertaken to control risk and assure the safety integrity of the rail infrastructure for trains operating on the ARTC network - like the one involved in this incident - relied solely on the methodology adopted by the subcontracted signal team on the day," Ms Hughes said.
In response, South Australia's Rail Commissioner has amended work instructions relating to work such as that involved in this incident.
"When a level crossing has active warning equipment, that forms the primary engineered risk control for managing safety at the road-rail interface, and it must operate correctly," Ms Hughes summarised.
"Any installation or alteration of a signalling system introduces the potential risk of this not happening. This risk must be managed appropriately.
"It is essential that rail transport operators and rail safety workers plan, document and implement effective testing systems and auditable practices to ensure that new or altered safety-critical railway infrastructure is rigorously verified and validated to assure the safety integrity of the infrastructure."
You can find here the final report: Level crossing irregularity involving freight train 1MP9 at Torrens Road, Ovingham, South Australia, on 7 December 2020
