SHEDULE EVALUATION (FATIGUE)
When contemplating a change of schedules, there are many factors to consider as well a many viewpoints from which those factors are considered. With 24 hour compressed work schedules, fatigue is far and away of most concern. The use of a FATIGUE INDEX is invaluable as a major indicator of the viability of a schedule. Studies show that for any shift the chances of error or accident increase during the course of that shift. It has also been widely recognised that these factors increase for each successive shift. The rest period between shifts has also been shown to be a factor when considering fatigue. This subject is extensively researched in a report prepared by QinetiQ Centre for Human Sciences & Simon Folkard Associates Limited for the Health and Safety Executive 2006, Entitled The WHITE UPS calculates as follows to approximate the above findings: For each shift, the length in hours is multiplied by a factor of 0.4 multiplied by the consecutive workday number of the shift. (Nightshift hours – 10pm to 6am - are calculated with a factor of 0.6 to account for extra risk factors.) Example: For a day shift of 10 hours on the third consecutive workday, the calculation is 10 multiplied by (0.4 * 3) for a score of 12. The total score is divided by the number of weeks in the schedule. The EFFICIENCY INDEX
of a schedule is an indication of how closely the schedule matches the SERVICE MODEL. It is arrived at by mapping the low and sustained peak period manpower produced by the schedule (both before and after the peak), and applies values derived from the SERVICE MODEL (i.e. high and low service demand and differential between high and low.) Chart Comparing 6 Different Shift Models |
SHIFT MODEL |
FATIGUE INDEX |
EFFICENCY INDEX |
AVERAGE REST BETWEEN SHIFTS |
DAY OFF RATIO |
WEEKEND OFF RATIO |
9am to 5pm Mon-Fri |
48 |
Not applicable |
16 HOURS |
28.5% |
100% |
The WHITE UPS |
52 * |
80 to 100% |
12.3 HOURS |
50% |
50% |
12-Hour 4/4 ** |
52.5 |
30 - 40% |
16 HOURS |
50% |
37.5% |
OTTAWA (UK) |
54.4 |
30 - 40% |
14.3 HOURS |
40% |
40% |
TRADITIONAL (UK) |
78.4 |
30 - 40% |
16 HOURS |
25% |
25% |
The TPS CWW |
80.6 |
30 - 40% |
14.6 HOURS |
40% |
40% |
* 52.3 for fixed shifts
** This schedule averages 42 work hours per week.