This fatigue calculator checks a worker's roster against your company's limits. Enter their shifts and it shows, shift by shift, where they go over the most hours in one shift, the most hours in any 7 days, or the least rest between shifts.
Traffic control is long shifts, early starts, night work and a lot of driving. Fatigue slows reactions and clouds judgement, and a tired controller standing next to live traffic, or driving home after a night shift, is at real risk. A roster that looks fine on a spreadsheet can hide a 5-hour turnaround or a 60-hour week. This tool finds them.
How it's worked out
For each shift you enter a date, a start time and a finish time. The calculator then:
- Shift length = finish − start. If the finish is earlier than the start, the shift is read as finishing the next day, so 18:00 to 06:00 is 12 hours.
- Sorts every shift by when it starts, so you can enter them in any order.
- Rest before a shift = this shift's start − the previous shift's finish.
- Hours in 7 days = the hours worked in the 168 hours from the start of each shift. The highest of these is the "most in any 7 days" figure.
- Flags a breach when a shift is longer than your maximum, the rest before a shift is shorter than your minimum, or the 7-day total from any shift start is more than your weekly limit.
- Warns about overlaps when one shift starts before the previous one has finished, which usually means a typing mistake in a date or time.
The summary shows total hours, the most hours in any 7 days, the longest shift and the shortest rest, each marked if it breaks a limit, plus a table of every shift.
The default limits are not the law
The calculator starts with 12 hours in one shift, 50 hours in any 7 days and 10 hours' rest between shifts. These are TrafWise's suggested starting points. They're not a legal limit and they may not suit your work.
There's no single national maximum shift length for traffic controllers. WHS laws in every state and territory require employers to eliminate or minimise risks to health and safety so far as is reasonably practicable, and fatigue is one of those risks. That means you set your limits from:
- your fatigue risk assessment, which looks at shift length, time of day, the type of work, heat, travel and the worker
- your contracts, because many principal contractors set their own shift and rest limits
- your award or enterprise agreement, which sets rules on breaks and shiftwork
- the code of practice or guidance in your state
In NSW, SafeWork NSW's Code of Practice Managing the risk of fatigue at work commenced on 20 February 2026. Approved codes describe how to meet your duties and can be used as evidence of what's known about a hazard. Elsewhere, Safe Work Australia and your state regulator publish fatigue guidance. Our guide to fatigue management for traffic controllers covers what a good fatigue plan includes.
Fatigue calculator worked example
An allocator has rostered a controller for five day shifts, Monday to Friday, 06:00 to 16:30. On Friday a night job comes in, and the same controller is put on 22:00 to 05:00.
| Shift | Hours | Rest before | Hours in 7 days from here |
|---|---|---|---|
| Mon 06:00–16:30 | 10.5 | – | 59.5 (over 50) |
| Tue 06:00–16:30 | 10.5 | 13.5 h | 49.0 |
| Wed 06:00–16:30 | 10.5 | 13.5 h | 38.5 |
| Thu 06:00–16:30 | 10.5 | 13.5 h | 28.0 |
| Fri 06:00–16:30 | 10.5 | 13.5 h | 17.5 |
| Fri 22:00–05:00 | 7.0 | 5.5 h (under 10) | 7.0 |
The calculator finds 2 issues: only 5.5 hours' rest between Friday's day shift and the night shift, and 59.5 hours in the 7 days from Monday. No single shift is longer than 12 hours, so each shift on its own looks fine. It's the pattern that's the problem.
The fix is to give the night job to someone who hasn't worked that week, or to take this controller off Friday's day shift. If it truly must go ahead, record the risk assessment and the extra controls, and think hard about how they'll get home at 5 am after a 23-hour day.
Night shifts
Night work adds to fatigue, and the drive home after a night shift is a serious risk. Try the "run of night shifts" example: six nights from 18:00 to 06:00 are 12 hours each with 12 hours' rest between them. No shift is too long and no rest is too short, but the 7 days from the first shift add up to 72 hours and from the second 60 hours, so the calculator flags both.
When you roster nights:
- keep runs of nights short and give recovery days after them
- avoid swapping a worker between days and nights in the same week
- plan rest breaks, water and relief, especially for controllers at fixed positions
- plan how people get home, and offer a rest area or transport after long shifts
Our guide to driving home after night shift has more on the commute.
Heavy vehicle drivers
If your crew drives a truck over 12 t GVM, such as some truck-mounted attenuators and sign trucks, the heavy vehicle fatigue laws apply as well as WHS. Under the National Heavy Vehicle Regulator's standard hours for solo drivers:
| In any | Most work | Rest |
|---|---|---|
| 8 hours | 7.5 hours | – |
| 11 hours | 10 hours | – |
| 24 hours | 12 hours | at least 7 continuous hours of stationary rest |
This calculator doesn't check those rules. Use a work diary or electronic work diary, and the NHVR's guidance, for heavy vehicle drivers.
What the calculator doesn't count
- Travel. Driving to and from site adds to fatigue but isn't counted. On regional jobs it can add hours to each day.
- Second jobs. Ask workers about other work.
- Breaks inside the shift. The award requires meal breaks, for example no more than 5 hours without one under the Building and Construction General On-site Award. The shift hours calculator works out paid hours after breaks.
- How people actually slept. A roster can be perfect and a worker can still turn up unfit. A pre-start check such as the Take 5 card gives them a chance to say so.
When to get professional advice
Get help from a WHS professional, your industry association or your state regulator when:
- you're writing or reviewing a fatigue management policy
- a contract sets limits you're not sure you can meet
- you run long night works, emergency call-outs or work in extreme heat
- there's been an incident where fatigue may have played a part
Our guide to rostering without breaking fatigue rules shows how allocators build rosters that pass these checks.