Chapter 3  Manual Fatigue Audit System
Safety Management Systems Training
Table of Contents
Overview
For organizations with relatively simple schedules or that may not want to invest in software, manual calculations can also be performed to generate scores that provide an indication of fatigue likelihood. A fatigue likelihood scoring matrix uses five scheduling parameters to predict sleep opportunity. These can be used to estimate the degree of workrelated fatigue produced by a given schedule:

Total number of hours worked in a sevenday period. Not surprisingly, as total hours worked increases, sleep opportunity decreases.

Maximum length of an individual shift. As the length of a given shift increases, the subsequent sleep opportunity decreases.

Minimum length of a short break. A short break is defined as a single sleep opportunity between work periods. It is typically shorter than 32 hours. Not surprisingly, as the break between shifts decreases, so does sleep opportunity.

Total number of hours worked between 9 p.m. and 9 a.m. in a sevenday period. This parameter takes into account late finishes, early starts, and night work. All of these will reduce night sleep opportunity and result in a significant reduction in total sleep opportunity.

Frequency of long breaks. A long break is defined as a period of two night sleeps with a nonworking day in between. Long breaks typically provide a significant opportunity to recover from sleep loss accumulated over a sequence of work periods. A schedule can be scored on each of the five parameters using the following table.
Fatigue Likelihood Scoring Matrix for Work Schedules
Score  0  1  2  4  8 

a) Total hours per 7 days  36 hours  36.1 – 43.9  44 – 47.9  48 – 54.9  55+ 
b) Maximum shift duration  8 hours  8.1 – 9.9  10 – 11.9  12 – 13.9  14+ 
c) Minimum short break duration  16 hours  15.9 – 13  12.9 – 10  9.9 – 8  8 
d) Maximum night work per 7 days  0 hours  0.1 – 8  8.1 – 16  16.1 – 24  24+ 
e) Long break frequency  1 in 7 days  1 in 7 days  1 in 14 days  1 in 21 days  1 in 28 days 
The points for each parameter are added up to provide a score between 0 and 40 that indicates the degree of sleep opportunity provided by the schedule. Schedules with a lower score offer a greater sleep opportunity. The figure below shows several schedules scored using this approach.
Fatigue Likelihood Score
Examples of different schedules scored using the Fatigue Likelihood Scoring Matrix
Example 1
Day  Description  Start  Finish 

1  Morning  0500  1400 
2  Morning  0500  1400 
3  Afternoon  1330  2230 
4  Afternoon  1330  2230 
5  Off  0000  0000 
6  Night  2200  0600 
7  Night  2200  0600 
Using the five parameters, this schedule would be scored as follows:

The total number of hours worked during the sevenday work period is 52 (4 points).

The maximum shift duration is 9 hours (1 point).

The minimum time off between shifts (short break) is 15 hours (1 point).

The total hours of night work scheduled for the sevenday period is 23. This includes 4 hours on each of the morning shifts due to the early shift starts, 1.5 hours on each of the afternoon shifts due the late finish, and 8 hours on each of the night shifts (4 points).

The long break frequency is 1 day within the 7 days of the schedule before the individual starts the night shift on Day 6 (0 points).
The total score for the above schedule is 10 points.
Example 2
Day  Description  Start  Finish 

1  Day  0600  1400 
2  Day  0600  1400 
3  Off  0000  0000 
4  Afternoon  1400  2300 
5  Afternoon  1400  2300 
6  Afternoon  1400  2300 
7  Night  2300  0600 
Using the five parameters, this schedule would be scored as follows:

The total number of hours worked during the sevenday work period is 50 (4 points).

The maximum shift duration is 9 hours (1 point).

The minimum time off between shifts (short break) is 15 hours (1 point).

The total hours of night work scheduled for the sevenday period is 19. The employee works 3 hours on each of the morning shifts due to the early start, 2 hours on each of the afternoon shifts due the late finish, and 7 hours on the night shift (4 points).

The long break frequency is 1 day before the individual starts the afternoon shift on Day 4 (0 points).
Le pointage total de l’horaire cidessus est de 10 points.
Summary
Any work schedule can be run through this scoring system. For example:

Monday to Friday, 9 a.m. to 5 p.m (40 hours) receives a score of 1

Monday to Friday, 3 p.m. to 11 p.m. (40 hours) receives a score of 3

4 days on – 4 days off (2 days from 6 a.m. to 6 p.m., 2 days from 6 p.m. to 6 a.m., for a total of 48 hours) receives a score of 14

Monday to Friday, 6 a.m. to 6 p.m. (60 hours) receives a score of 16

7 night shifts of 12 hours, 9 p.m. to 9 a.m. (84 hours), followed by 7 days off receives a score of 22
Based on a company’s risk assessments, managers can consider whether existing work schedules produce acceptable levels of fatiguerelated risk.
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