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Fatigue Through Nightshifts Fatigue Through Nightshifts in Successionin Succession
Joint Coal Board Health and Safety Trust’s research priority on fatigue and
stress.
Nick MabbottARRB Transport Research Ltd.
Focus on Rosters and Shifts
Debate on length of shifts (8 Vs 12)
Focus on length of rosters
Considerable argument over roster pattern
Research Questions to Answer
1 What is the most important contributor to acute fatigue in open cut mining? Is it length of shift (eg. 8 hours Vs 12 hours) or is it time of day (eg. circadian effects)?
2 What is the limit of successive night shifts before chronic fatigue affects
operator performance in open cut mines?
Methodology
Funded by Coal Services
Open cut mine selected
8 haul trucks fitted with ARRB FMD
Testing for slow reactions to stimuli
Methodology
24 drivers being tested for 10+ weeks (17 male & 7 female)
14 N, 1 off, 13 D, 7 off roster (12-hours)
Collecting real-time performance data
1 What is the most important contributor to acute fatigue in open cut mining?
If the length of shift is the major issue, we should see lowered performance toward the end of the shift
If it is circadian effects, we should see lowered performance during the circadian low points (0000 hrs to 0500/0600 hrs
Length of Shift Performance Vs Circadian Influence - Shift 1
Night 1 - Wednesday
0
0.5
1
1.5
2
2.5
18
00
- 1
83
0
19
00
- 1
93
0
20
00
- 2
03
0
21
00
- 2
13
0
22
00
- 2
23
0
23
00
- 2
33
0
00
00
- 0
03
0
01
00
- 0
13
0
02
00
- 0
23
0
03
00
- 0
33
0
04
00
- 0
43
0
05
00
- 0
53
0Time of Day
1300
1400
1500
1600
1700
1800
RC 4's
Z score
Mean RT
So What’s the Answer to Q1???
What is the most important contributor to acute fatigue in open cut mining? Is it length of shift (eg. 8 hours Vs 12 hours) or is it time of day (eg. circadian effects)?
The data shows that: There appears to be no length of shift effect. The circadian influence is very strong, however, it
does not match sleep or crash data.
2 What is the limit of successive night shifts before chronic fatigue affects operator
performance in open cut mines?
Is there a cut-off point where safety is compromised by fatigue as measured by operator performance?
Length of Shift Performance & Circadian Influence - Night 2
Night 2 - Thursday - Tests per hour
0
1
2
3
4
5
18
00
- 1
83
0
19
00
- 1
93
0
20
00
- 2
03
0
21
00
- 2
13
0
22
00
- 2
23
0
23
00
- 2
33
0
00
00
- 0
03
0
01
00
- 0
13
0
02
00
- 0
23
0
03
00
- 0
33
0
04
00
- 0
43
0
05
00
- 0
53
0
Time of Day
0
4
8
12
16
20
Fc 3's
Fc 4's
Tests
Length of Shift Performance & Circadian Influence - Night 3
Night 3 - Friday - Tests per hour
0
1
2
3
4
5
18
00
- 1
83
0
19
00
- 1
93
0
20
00
- 2
03
0
21
00
- 2
13
0
22
00
- 2
23
0
23
00
- 2
33
0
00
00
- 0
03
0
01
00
- 0
13
0
02
00
- 0
23
0
03
00
- 0
33
0
04
00
- 0
43
0
05
00
- 0
53
0
Time of Day
0
4
8
12
16
20
FC 3's
FC 4's
Tests
Length of Shift Performance & Circadian Influence - Night 4
Night 4 - Saturday - Tests per hour
0
1
2
3
4
5
18
00
- 1
83
0
19
00
- 1
93
0
20
00
- 2
03
0
21
00
- 2
13
0
22
00
- 2
23
0
23
00
- 2
33
0
00
00
- 0
03
0
01
00
- 0
13
0
02
00
- 0
23
0
03
00
- 0
33
0
04
00
- 0
43
0
05
00
- 0
53
0
Time of Day
0
4
8
12
16
20
Fc 3's
FC 4's
Tests
Length of Shift Performance & Circadian Influence - Night 5
Night 5 - Sunday - Tests per hour
0
1
2
3
4
5
18
00
- 1
83
0
19
00
- 1
93
0
20
00
- 2
03
0
21
00
- 2
13
0
22
00
- 2
23
0
23
00
- 2
33
0
00
00
- 0
03
0
01
00
- 0
13
0
02
00
- 0
23
0
03
00
- 0
33
0
04
00
- 0
43
0
05
00
- 0
53
0
Time of Day
0
4
8
12
16
20
FC 3's
FC 4's
Tests
Length of Shift Performance & Circadian Influence - Night 10
Night 10 - Friday - Tests per hour
0
1
2
3
4
5
18
00
- 1
83
0
19
00
- 1
93
0
20
00
- 2
03
0
21
00
- 2
13
0
22
00
- 2
23
0
23
00
- 2
33
0
00
00
- 0
03
0
01
00
- 0
13
0
02
00
- 0
23
0
03
00
- 0
33
0
04
00
- 0
43
0
05
00
- 0
53
0
Time of Day
0
4
8
12
16
20
FC 3's
FC 4's
Tests
Length of Shift Performance & Circadian Influence - Night 13
Night 13 - Monday - Tests per hour
0
1
2
3
4
5
18
00
- 1
83
0
19
00
- 1
93
0
20
00
- 2
03
0
21
00
- 2
13
0
22
00
- 2
23
0
23
00
- 2
33
0
00
00
- 0
03
0
01
00
- 0
13
0
02
00
- 0
23
0
03
00
- 0
33
0
04
00
- 0
43
0
05
00
- 0
53
0
Time of Day
0
4
8
12
16
20
FC 3's
FC 4's
Tests
Length of Shift Performance & Circadian Influence - Night 14
Night 14 - Tuesday - Tests per hour
0
1
2
3
4
5
18
00
- 1
83
0
19
00
- 1
93
0
20
00
- 2
03
0
21
00
- 2
13
0
22
00
- 2
23
0
23
00
- 2
33
0
00
00
- 0
03
0
01
00
- 0
13
0
02
00
- 0
23
0
03
00
- 0
33
0
04
00
- 0
43
0
05
00
- 0
53
0
Time of Day
0
4
8
12
16
20
FC 3's
FC 4's
Tests
Nightshifts in Succession?
Night Shift - Average Tests per hour
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1.1
1.2
1 2 3 4 5 6 7 8 9 10 11 12 13 14
Night Number
7
7.5
8
8.5
9
9.5
10
FC 3's
FC 4's
Tests
Circadian Effects
All nights
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
18
00
- 1
83
0
19
00
- 1
93
0
20
00
- 2
03
0
21
00
- 2
13
0
22
00
- 2
23
0
23
00
- 2
33
0
00
00
- 0
03
0
01
00
- 0
13
0
02
00
- 0
23
0
03
00
- 0
33
0
04
00
- 0
43
0
05
00
- 0
53
0
Time of Day
1350
1400
1450
1500
1550
1600
FC 4's
Z score
Mean RT
Length of Night Shift Performance & Circadian Influence
18
00
- 1
83
0
19
00
- 1
93
0
20
00
- 2
03
0
21
00
- 2
13
0
22
00
- 2
23
0
23
00
- 2
33
0
00
00
- 0
03
0
01
00
- 0
13
0
02
00
- 0
23
0
03
00
- 0
33
0
04
00
- 0
43
0
05
00
- 0
53
0
S1
S2
S3
S4
S5
S6
S7
S8
S9
S10
S11
S12
S13
S14
Time of Day
Nights 1 - 14 - FC 4's per hour
2.5-3
2-2.5
1.5-2
1-1.5
0.5-1
0-0.5
2 What is the limit of successive night shifts before chronic fatigue affects operator
performance in open cut mines? Any takers? Data suggests that some nights are
worse (performance-wise) than other nights 2, 7, 13 & 14
Sunday & Tuesday nights are bad Circadian effects present Hard to determine cut-off point as night 2
& 7 are worse than all <12
Individual VariabilityOperator A - Tests per hour
0
0.25
0.5
0.75
1
1.25
1.5
1.75
2
2.25
2.5
1800
- 1
830
1930
- 2
000
2100
- 2
130
2230
- 2
300
0000
- 0
030
0130
- 0
200
0300
- 0
330
0430
- 0
500
0600
- 0
630
0730
- 0
800
0900
- 0
930
1030
- 1
100
1200
- 1
230
1330
- 1
400
1500
- 1
530
1630
- 1
700
Time of Day
0
2
4
6
8
10
12
14
16
18
20
FC 3's
FC 4's
Tests
Individual VariabilityOperator B - Tests per hour
00.5
11.5
22.5
33.5
44.5
55.5
66.5
718
00 -
183
0
1930
- 2
000
2100
- 2
130
2230
- 2
300
0000
- 0
030
0130
- 0
200
0300
- 0
330
0430
- 0
500
0600
- 0
630
0730
- 0
800
0900
- 0
930
1030
- 1
100
1200
- 1
230
1330
- 1
400
1500
- 1
530
1630
- 1
700
Time of Day
0
2
4
6
8
10
12
14
16
18
20
FC 3's
FC 4's
Tests
FRQ Score Correlation with Tests Per Hour
F 4's per hour versus FRQ - Night Shift y = 0.0171x - 0.7323
R2 = 0.6139
0.00
0.50
1.00
1.50
2.00
0 20 40 60 80 100 120 140
FRQ
FRQ Score Correlation with F 4
F 4's per hour versus FRQ - Day Shift y = 0.0196x - 0.6676
R2 = 0.7647
0.00
0.50
1.00
1.50
2.00
0 20 40 60 80 100 120 140
FRQ
What should we do about this?
Direct more attention to individual selection (53% obese).
Observe patterns of high and low performance and try different countermeasures.
Promote a culture where your drivers are willing to admit they are tired & in need of a break.
More to Come...
Data will be built up more over time - will be able to test rosters against each other for performance.
Results may change the way we discuss what is best for operators (eg. FRQ and a higher individual focus).
Many Thanks
Coal Services Sons of Gwalia MacMahons Personnel at Carosue Dam Bob Lloyd - ARRB
Wednesday afternoon - Presentation of PFMS