On 23 March 2005, a distillation tower at BP's Texas City refinery was filled far beyond its normal level. Hydrocarbon erupted from a vent stack, found an ignition source and exploded. Fifteen people died and 180 were injured.
Nobody at the controls was asleep. But by that morning, operators had been working 12-hour shifts for 29 or more consecutive days.
What fatigue actually looks like
Ask most people to picture a fatigued worker and they picture someone nodding off. Head drops, eyes close, the forklift drifts into the racking.
That does happen. But it is the rare, visible end of the problem. The common version is much quieter, and much harder to spot from the outside.
The US Chemical Safety Board's investigation described it precisely. Fatigue causes cognitive fixation and impaired judgement. Operators can lock on to one reading, in this case a level that appeared to be falling, and stop weighing the other signals around them. The Board concluded that fatigue of the operations personnel contributed to overfilling the tower.
That is what fatigue looks like in a control room, on a scaffold or behind the wheel of a delivery van. A person who is awake, trying hard and working from a picture of the plant that stopped being true an hour ago.
HSE's definition makes the same point. Fatigue is a decline in mental and physical performance caused by prolonged exertion, sleep loss or disruption of the body clock. Slower reactions. Missed steps. Poorer judgement of risk. None of it requires anyone to close their eyes.
Why "get more sleep" is not a control
The instinctive response to fatigue is to treat it as a personal matter. Look after yourselves. Get a good night's sleep. Speak up if you're tired.
There is a fair argument for that. People do have lives outside work. Second jobs, young children, long commutes and bad habits all eat into rest, and no employer can control them.
But look again at Texas City. The CSB found that BP had no fatigue-prevention policy for its refinery staff. The people at the controls hadn't chosen a month of 12-hour days. Staffing levels and the rota had chosen it for them. The Baker Panel, which reviewed BP's US refineries after the explosion, found overtime levels it judged excessive and linked them to understaffing.
That is the heart of it. For shift workers, most fatigue is designed into the work before anyone clocks on. It comes from:
- how long the shift is
- how many shifts run back to back
- how much rest sits between them
- how much of the work falls in the small hours, when the body clock is at its lowest
- whether breaks are real or theoretical
- how demanding or safety-critical the task is at the point people are most tired
A poster can't fix any of those. A rota can.
HSE puts fatigue among the root causes of some of the worst accidents on record, including Herald of Free Enterprise, Clapham Junction, Chernobyl and Texas City. It also estimates that fatigue-related accidents at work cost the UK between £115 million and £240 million a year. With more than 3.5 million shift workers in the UK, this is not a niche problem for refineries.
The legal floor, and why it isn't enough
Every rota in Great Britain has to sit within the Working Time Regulations 1998. For adult workers, the headline rules are:
- 11 hours' rest between working days
- an uninterrupted 24 hours off each week, or 48 hours each fortnight
- a 20-minute break for a working day longer than six hours
- a 48-hour average working week, unless the worker opts out
- night workers averaging no more than eight hours in any 24, normally over 17 weeks
Those limits matter. But a rota can respect every one of them and still be a poor design. Twelve-hour nights, a quick changeover and a run of seven shifts can all sit inside the rules while stacking fatigue risk higher and higher.
The law sets the floor. The Management of Health and Safety at Work Regulations 1999 still require you to assess the risks your work creates, and HSE's shift work guidance, HSG256, treats fatigue as one of them. HSE also publishes a free Fatigue and Risk Index calculator for comparing shift patterns. If you've never run your rota through it, the results can be an uncomfortable read.
Industry learned the lesson slowly. After Texas City, the CSB called for fatigue guidelines for refining and petrochemicals that would limit hours and days of work. The American Petroleum Institute's RP 755 on fatigue risk management came out of that recommendation. It took a disaster to get there.
Five things to check on Monday
You don't need a consultant to start. Take your current rota and a supervisor who knows the floor, and ask:
- What is the longest run of consecutive shifts anyone has worked in the last three months? Include overtime and swaps, not just the published pattern.
- Where are the short changeovers? A finish at 22.00 and a start at 06.00 leaves eight hours, three short of the standard 11, and that's before travel, eating and sleep.
- What safety-critical work happens between 02.00 and 06.00? Start-ups, isolations, lifts and permit handovers can often move to a better hour.
- Is overtime covering a vacancy? If the same names fill the same gaps every week, you have a staffing problem wearing a rota costume.
- What happens when someone says "I'm too tired to do this safely"? If the honest answer is "nothing good", people will stop saying it.
Picture a night-shift supervisor at 04.30, three nights into a run, being told the permit for a line break is ready. Everyone is keen to get it done before days arrive. The questions above are designed for that moment, not for the training room.
The question worth asking
The operators at Texas City were experienced, conscientious people doing a hard job in a system that had quietly stopped protecting them. The same is true on plenty of sites today, where the rota has become normal simply because nobody has looked at it closely.
What's the longest run of shifts you've seen accepted as normal, and what finally changed it?
Sources
- US Chemical Safety Board, BP America Texas City Refinery Explosion, final report (2007)
- HSE, Human factors: fatigue
- HSE, HSG256 Managing shift work
- UK Government guidance, Rest breaks at work; Night working hours
- Working Time Regulations 1998; Management of Health and Safety at Work Regulations 1999
- American Petroleum Institute, RP 755 Fatigue Risk Management Systems
First published on the HartfellCo LinkedIn page, 17 September 2026.
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