Ella Dahan
Principal Risk and Safety Intelligence Analyst, RSSB
A high-performing railway must be safe, resilient, and reliable. But in such a complex system, even small issues can create a ripple effect of risk.
Delays are a prime example of events that can increase secondary risks and disruption. Crowded stations and changes to departure times and platforms can make pedestrian incidents more likely. Passengers could become frustrated and aggressive towards staff. Train drivers may experience more red signals, increasing the likelihood of a signal passed at danger (SPAD).
We’ve developed a new model to quantify these ‘knock-on’ impacts. It allows for more informed decision making, especially when operational choices might introduce delays. If delays were eliminated, the industry could realise:
- a 16% reduction in passenger train SPADs
- a 37% reduction in freight train SPADs
- a 53% reduction in slips, trips, and falls
- a 47% reduction in incidents at the platform-train interface (PTI)
- a 34% reduction in staff assaults.
A smarter system
The original knock-on risk model was developed in 2014. It helped create operational rules for GSM-R radio failures. Early analysis showed a clear link: lower operational performance correlated with a higher likelihood of incidents. These included SPADs, slips, trips, and falls, PTI incidents, and staff assaults, which together represent 47% of the total network risk. The initial model saw success in various applications, from managing defective on-train equipment to determining speed restrictions during extreme weather.
Our latest research used more detailed post-COVID operational data to quantify short-term and long-term safety impacts of delays. It also addressed risks associated with stranded trains. The improved knock-on risk model offers significant benefits for industry.
Planning for adverse conditions
The knock-on risk model, in essence, gives industry the ability to quantify the short-term effects that delays have on safety. This helps in managing adverse conditions, such as during extreme weather or when a train becomes stranded. Decision makers can better assess whether slowing or stopping trains is appropriate and how safety will be affected. Wide adoption would mean a network that remains safe and reliable during adverse conditions.
Shaping policy and investment
The knock-on risk model can help to quantify the safety benefits of proposed changes. The model outputs can be used to strengthen business cases or support policy decisions that impact performance. These might target a cause of disruption, such as by reducing trespass, or reduce disruption from that cause, for example improving the response to trespass.
To get even more from this rich data-led evidence base, we’ve also provided a means to quantify the wider societal impact of delays and disruptions due to modal shift. Continued delays and disruptions discourage rail use, encouraging modal shift to less safe modes such as cars or motorcycles. When people shift to other modes of transport, their fatality risk is 30 times higher compared to if they travelled by rail.
I encourage rail leaders to share the full report with their risk and safety experts and reach out with any questions.