Magic Bullet or Swiss Cheese? Developing SPAD mitigation measures for New Zealand

Signals Passed at Danger (SPADs) are a recognised critical risk for rail operations and the focus of extensive research within rail human factors (HF). The New Zealand (NZ) rail safety regulator, NZ Transport Agency,... [ view full abstract ]

Signals Passed at Danger (SPADs) are a recognised critical risk for rail operations and the focus of extensive research within rail human factors (HF). The New Zealand (NZ) rail safety regulator, NZ Transport Agency, commissioned Interfleet’s HF team to review the current HF knowledge regarding SPAD mitigations. We worked with NZ stakeholders, including KiwiRail and Transdev, to review their SPAD reduction strategies to ensure they reflected international best practice in terms of technology and were cognisant of human performance issues.
KiwiRail’s current SPAD reduction strategy includes:
• Improved investigation and analysis.
• Driver management through recruitment and competence management.
• Protection through signalling systems.
• Exploiting and adopting current/emerging technologies.
Traditionally the railway has relied heavily on human performance through the application of administrative controls and rules. The Rail Participants are now implementing driver based interventions such as risk-triggered commentary driving and stabilised approach procedures to improve human performance.
Whilst significant recent investment has resulted in the first deployment of the European Train Control System (ETCS) within Australasia the challenges of exploiting its full benefits on a multi modal railway are as yet unresolved. A shift in focus from administrative to robust engineering controls is also required to reduce SPAD risk in the track worker protection and the Track Warrant Control operating system domains.
Method
A targeted literature review was undertaken focusing on the latest understanding of human factors issues implicated in SPADs and international SPAD risk reduction with potential for application in NZ. We highlighted some of the problems encountered when applying SPAD tools and mitigations and found a lack of documented evidence of the effectiveness of specific programmes, barriers to application of SPAD mitigations and risks associated with implementation.
Findings
The literature identified that there is no magic bullet or single intervention for SPAD reduction; a broad spectrum of SPAD reduction interventions is needed to maintain sufficient layers of protection. These layers of protection are analogous to Reason’s Swiss Cheese Model and there are parallels with the Railway Management Maturity Model (RM3).
Outcomes
Interfleet worked with the stakeholders to develop a SPAD framework based on the RM3, which evaluates their organisational layers of protection. This enabled any gaps to be identified within each individual organisation’s SPAD strategy and give NZTA an overview of the industry as a whole, providing:
• An overview of the NZ industry SPAD strategy: the range of activities, who is doing what and how SPAD risk is addressed for different contexts of operation.
• Knowledge for an effectively targeted SPAD reduction strategy.
• Clear view of steps needed to achieve a mature SPAD strategy suitable for each operator.
Managing industry’s expectation of the SPAD ‘magic bullet’ is a challenge. This approach summarises the range of engineering and human performance issues that contribute to SPAD risk and provides assurance that NZ’s SPAD risk reduction approach efforts are aligned, inclusive of international best practice and that a holistic, industry-wide approach is required.