Level and Form of Risk Analysis

All risk assessments should fulfil the common stages of risk assessment. The specific methods used for each stage should be suitable and sufficient.

A suitable and sufficient risk assessment should be proportionate to the risk and scope of the system being assessed, see Forms of risk assessment below. It must also be practicable, especially with respect to the availability of data and information.  

A single form of HAZID is noted in this guide, as per the HAZID section.

  • Form of risk assessment

    Two forms of risk estimation are covered in this guide:

    • Quantified risk estimation - estimation of the likelihood or frequency of an adverse event using numerical data on incident frequency and consequence, typically applied to national, regional or whole route assessments
    • Risk rating – a form of assessment combining data and qualitative information to produce a risk rating from very low to very high, typically applied to local / small area risk assessment, such as a train station or depot.

    Risk rating can be applied by use of location specific incident data and knowledge of the location.  Quantified Risk Estimation for trespass may require data on the likelihood of fatal and major injuries which is less likely to be available for a single location.

    Quantified Risk Estimation can require more time than qualitative risk rating and so may be preferred when assessing higher value interventions.

    The time and cost of the assessment needs to be proportionate to the risk and cost of intervention.  If there is evidence that a large area/system, such as a section of rural running line, is low or very low risk (for example, due to a low or very low rate of incidents, as shown in the Define and Screen section), an option is to perform a qualitative risk rating. In this case, a qualitative risk assessment of a large area or system could be proportionate to the low level of incidents, unless there is evidence to the contrary.

    More information on these risk estimation methods is provided in the risk analysis web pages.

  • Level of risk assessment

    The extent (or level) of assessment should be proportionate to the risk as well as practicable in terms of what data is available.

    The guidance in the Define and Screen section may be used to rank a location. The decision on what level of assessment to apply for a given frequency, such as High or Medium, is the prerogative of the assessor. 

    In the case of lower risk areas, some options include:

    A HAZID, risk estimation and risk evaluation are advised in all cases.

    A higher risk area or where the intervention has a high cost, may require a cost-benefit assessment.

Haven’t found what you’re looking for?
Get in touch with our Senior Safety Intelligence Analyst for further information.
Siona Vass
Tel: 020 3142 5485
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