Risk Acceptance and Application of the Common Safety Method in the United States
Authors: Cockle John 
Published: June 2016

The Federal Railroad Administration (FRA) has published a Notice of Proposed Rulemaking (NPRM) that will require passenger rail operators in the United States to develop a System Safety Program using a risk-based hazard management approach. Identified as 49 CFR, Part 270 System Safety Rule [1], the NPRM describes the basic requirements for a system safety program plan, including the need for a method for accepting risk. The NPRM does not, however, identify how the responsible party should actually go about managing risk. That is left up to the railways themselves.

In Europe, hazard management is applied in the railroad industry (including high-speed rail systems) under the regulatory authority of the European Union. European Commission Regulation 352/2009/EC [2] outlines a Common Safety Method (CSM) on Risk Evaluation and Assessment for Railways of the European Union, commonly known as the CSM Regulation and the heart of the railway safety program in Europe. The CSM Regulation includes the standard risk assessment process elements: identification of the hazards, corresponding risks, mitigation measures to reduce the risk, and the resulting safety requirements to be fulfilled by the system under assessment. What sets the CSM Regulation apart from other risk assessment programs is that it provides a methodology for determining when acceptable risk is achieved. The risk acceptability of the system under assessment is evaluated using one or more of the following risk acceptance principles:

a) The application of relevant codes of practice;

b) A comparison with similar systems (reference systems);

c) Explicit risk estimation.

In essence, the responsible party can accept risk that has either been regulated to an acceptable level by an authority having jurisdiction or a widely-accepted industry practice, or if the risk has been successfully addressed by a similar railway system through that railway’s engineering and operational controls. If neither of these cases applies the responsible party can estimate the risk and choose to accept it or not. A common approach, even internationally, is to develop an explicit risk estimation process based on the U.S. Department of Defense Military Standard 882E (MIL-STD-882E) [3]. Safety hazards are identified, analyzed for risk (severity and probability), and mitigations are progressively applied until a level of safety is achieved that is as low as reasonably practicable.

The California High-Speed Rail Authority (CHSRA) has adopted a risk-based hazard management program to achieve an acceptable level of safety for the design, construction, implementation and operation of the California High-Speed Rail System. CHSRA has deliberately used both domestic and international guidance and standards in the development of this program in an effort to apply the most up-to-date processes and philosophies, and to draw upon the impressive safety legacy of international high-speed railway operators.

This paper will describe the relevant regulations and guidance (both domestically and internationally), review the elements of a risk acceptance program based upon the CSM Regulation, and apply the program to a select set of hazards to demonstrate how appropriate mitigations can be determined and residual risk accepted. The paper will also identify potential future applications for the CSM Regulation here in the United States, and will challenge the reader to manage hazards using a risk-based approach that incorporates the basic framework of the CSM Regulation.