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The Fatigue Risk Index

A bio-mathematical model for employees exposed to fatigue hazards when working shift rotations

The industry-leading Fatigue Risk Index (FRI) is used across a range of industries including emergency services, aviation ground crew, manufacturing, rail, energy and maritime.

FRI is the most popular fatigue risk management tool used for UK shift workers. It is validated with decades of research. It is the industry leading model for shift work fatigue risk management, supporting safety and operations managers in their obligations to reduce fatigue hazards and improve productivity across many industries.

FRI was originally commissioned by the UK Government Health & Safety Executive (HSE) and previously available from the HSE in an Excel spreadsheet. FRMSc has enhanced the speed, power, connectivity and user experience into the FRI+ model. FRI+ provides identical outputs to the original version but with a significantly improved interface, increased schedule capacity, a more robust approach and a better user experience. 

The original HSE version of FRI that was researched and developed by the team at FRMSc is no longer supported.

FRI is the standard adopted for the UK rail industry, aligning with RSSB and Network Rail regulations for fatigue risk management across all staff and subcontractors. FRMSc has been providing it to clients for over 10 years. In an independent review, the UK Rail Safety and Standards Board assessed FRI’s empirical model to be the most comprehensive fatigue and risk model available.

Our enhanced FRIPRO will be released soon. It has been designed to meet the needs of the FRM or Safety Manager. FRIPRO includes many of the features available in the SAFE and CARE aviation models including variable workload, fatigue scores every 15 minutes of duty and visible sleep periods. FRIPRO can also be connected to the HARVEST analytics package for greater oversight and analysis.

FRI+ has a comprehensive set of features including:
fri screenshot
FRIPRO enhances FRI+ by including:

FRI+ model provides scale, speed and security

rail industry approved

Rail industry Approved

Commissioned by the UK Health and Safety Executive and evaluated and endorsed by the UK Rail Safety and Standards Board (RSSB) and Network Rail. Used by rail companies world wide.

easy to use

Targeted Model

Developed from decades of original research and used extensively for shift work. Supports in-duty breaks and time on task variables.

fast and flexible

Fast, scalable & API-ready

FRI+ and FRIPRO are hosted on scalable cloud systems allowing thousands of schedules to be analysed rapidly. APIs available to connect with scheduling and timesheet software systems.


Operationally relevant

Supports “what if” scenarios to test new operational models and working patterns to meet varying workload and staff availability.

Intuitive user interface

User interface provides visualisation of fatigue and risk profiles, manual editing of rosters for fine tuning and detailed analytics

Cost effective

The FRI+ and FRIPRO biomathematical model platform provides unparalleled cost/performance for analysing fatigue in shift worker schedules.

Standalone or API interface
Rosters can be uploaded to FRI+ as Excel spreadsheets or directly integrated into rostering and timesheet data collection systems using our API.
Assess Planned or Actual Rosters
FRI+ can be used to model fatigue and risk for your actual rosters every time they are changed as well as assessing fatigue risk profiles for planned rosters.
Proactive analysis of new operations
FRI+ can be used to assess the impact of new operations through prospective analysis.
Incident Investigation
Post incident rosters can be analysed in FRI+ to understand worker fatigue state. This includes the ability to personalise an individual roster to take into account actual sleep and activity data.
Real-time roster analysis
Through our scalable cloud infrastructure, high-demand re-rostering can be accommodated for fast, effective analysis through our algorithm-only API.
Workload adaptation
Shift working demands vary depending on occupation and environmental conditions. FRI+ is adaptable to this varying workload.
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Using the Fatigue Risk Index

FRI+ is supported by FRMSc and available as a cloud-based model or as maintained fast API algorithm library. FRI+ can be tailored to specific occupations across different industries.

FRI+ uses updated algorithms and user interfaces on a powerful cloud hosting platform to provide you with a better and faster experience but with the same industry-accepted fatigue and relative risk metrics of the unsupported HSE version of FRI.

Rosters can be uploaded directly or integrated into rostering systems to take an automatic feed for analysis. Workload and alertness levels can be varied for each duty to take into account job and task differences.

The FRI+ output has also been enhanced providing more detailed outputs as well as the ability to optimise schedules within the user interface.

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An Introduction to Fatigue Risk Management Systems