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