Drilling Down on Roster Design

Recently my co-authors and I published a peer-reviewed journal article (open access, or in other words, free to read 😊) in the academic journal Annals of Work Exposures and Health (or ANNWEH). ANNWEH is the flagship journal for the British Occupational Hygiene Society. Click here for a link to the full article!

In the mining industry, fatigue management often only aims to comply with work-hours rules, rather than to quantify and mitigate fatigue risk. In addition, it can be (mis)guided by personal preferences and anecdotes or convention (the way it’s always been done), rather than through objective and validated tools. This is the goal of the study; to show how fatigue risk in shift and roster design in mining can be viewed objectively.

What we did?

We took ten of the most commonly worked shift and roster schedules in Western Australia (WA) fly in-fly out (FIFO) operations and looked at how fatigue risk changed throughout each roster.  Overall, we analysed 150 shifts and roster variations, including elements such as shift start times and travel durations to and from the operation.

We modelled each variation using the FAID “Standard” model; this is an established biomathematical model that estimates fatigue risk from hours-of-work patterns. In this analysis, we explicitly modelled “active” travel (home ↔ airport driving) and used flight timings that reflect common Perth-to-Pilbara or Perth-to-Goldfields flights used in mining.

Presented above is an example visualisation that we derived using the results of the biomathematical modelling. Green sections are low inherent fatigue risk, while red sections are high inherent fatigue risk. Risk while driving to and from home and the airport is presented in the bolded boxes, while time spent waiting for a flight or on a flight is in grey.

What did we find?

• For day shift only rosters, later starts and finishes (e.g., 07:00–19:00) reduce predicted fatigue risk
• For night shift only rosters, earlier starts and finishes (e.g., 05:00–17:00) reduce fatigue risk; however even then, these shifts were still higher risk than day shifts
• In rotating shift schedules, the night shift fatigue risk is of greater importance to control, and therefore earlier night shift and day shift start times (05:00-07:00) are better than later shift start times (07:00-19:00). An exception to this however is the backward-rotating 7 nights à 7 days à 7 off pattern, where later start times produced lower overall inherent fatigue risk
• Driving home from the airport, after finishing the last night shift, is of high fatigue risk

The takeaway message from the article isn’t to “always start earlier” or “always start later”; it is to identify and understand where inherent fatigue risk is present in your workplace, and make roster-related decisions with this information in mind.

What can companies do?

Practical controls that can be implemented to address inherent fatigue risk include:

• Undertake shift and roster analyses on current rosters at your business to develop a risk profile
• Analyse potential future state rosters using biomathematical modelling to get an objective understanding of potential changes to inherent fatigue risk
• Educate workers on sleep health and fatigue risk – particularly during night shifts and while operating vehicles
• For FIFO night shift operations, ending the last night shift early and providing a sleep opportunity to workers (perhaps during 02:00–06:00) before site‑to‑airport travel can reduce fatigue risk while driving
• Similarly, taxi vouchers can be provided or transport can be organised from the home airport. If the fatigued individual isn’t driving the vehicle that’s getting them home, their fatigue does not result in fatigue risk

The analysis we undertake in our shift and roster scientific assessment service follows very similar principles and methodology to that used within this article. We tailor all analysis to your particular context, explore current and potential future state options, and combine modelling results, insightful visualisations and expert opinion to provide commentary and recommendations that you can trust.

Industries we support include mining, oil and gas, transport, defence, engineering, construction, agriculture, and energy. Clients include BHP, Rio Tinto, Peabody, Anglo Gold Ashanti Australia, Gold Fields, CBP Contractors, Macmahon Holdings, Bechtel, Metro Trains Melbourne, Mineral Resources Limited, CBH and the Australian Submarine Corporation.

For more information on this service or any other services that we offer, please contact me at tim.smithies@melius.com.au