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Safety Risk Model - Overview

Safety Risk Model

Safety Risk Model

Chris Harrison

Principal Risk Analyst

A good understanding of risk is required to deliver a safer, more efficient and sustainable rail system. RSSB’s Safety Risk Model provides a network-wide view of risk and is used by companies and projects to support risk-based decision making.

​What is the SRM?

The Safety Risk Model (SRM) provides a network-wide risk profile for the GB railway. It has underpinned the industry’s evidence and risk-based approach to safety management for the best part of two decades.

  • It provides a trusted starting point for quantified risk analysis. For example, it was instrumental to the development of new rules for train radio failures and defective on-train equipment, and supported train operator decisions about retro-fitment of train doors and TPWS equipment.
  • Train operators use the SRM-Risk Profiling Tool to understand the safety of their operation. This forms part of their suitable and sufficient risk assessment, which is required by ROGS.
  • The SRM national risk profile helps to focus collaborative cross-industry effort and informs the industry strategy Leading Health and Safety on Britain’s Railway.
  • SRM risk estimates are used to calibrate other industry risk tools, including the tools Network Rail uses to manage risk from with signal over-runs and at level crossings.

How does the SRM measure risk?

The SRM estimates the underlying risk from the operation and maintenance of the mainline railway.

It comprises a series of models representing the hazardous events with potential to cause harm to workforce, passengers and other members of the public. RSSB uses the model to produce risk estimates for 131 hazardous events and almost 3,000 event precursors.

The SRM measures risk in terms of frequency, how often we expect something to occur, and consequence, the expected level of harm that arises when it does. Risk is presented in units of Fatalities and Weighted Injuries (FWI) per year. To calculate FWI injuries are weighted according to their relative severity.

Risk estimates are derived from historical accident data, fault and event-tree modelling, structured expert judgement from technical specialists, and statistical methods.

How can I use the SRM?

A brief overview of SRM version 8.5 is available to download and full tables of risk estimates are available for RSSB members to download from the Rail Risk Portal.

You can use SRM to support risk assessments and to understand how the risk from your operation compares with and contributes to the network-wide risk. This can help you take and justify safety-related decisions with confidence in line with the rail industry’s Taking Safe Decisions framework.