Shiftwork, Work Scheduling and Safety: How Much Is Too Much

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Shiftwork, Work Scheduling and

Safety: How Much Is Too Much

Wayne S. Maynard, CPE, CSP, ALCM Liberty Mutual Group, Hopkinton, MA

George E. Brogmus, MS, CPE, M.Erg.S. Liberty Mutual Group, Burbank, CA

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March 12-15, 2007 Dallas, Texas

Shiftworkers’

Problems

• Disturbed sleep • Increased risk of accidents • Impaired psychological health • Impaired physical health • Impoverished family/social life • Increased errors/accidents • Reduced productivity/quality • Increased sickness absence • Increased labour turnover • Reduced moral

Employers’

Problems

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Percent Productivity vs. Continuous Weeks of O/T 50 50 60 60 70 70 80 80 90 90 100 100 0 0 ₁₁ ₂₂ ₃₃ ₄₄ Weeks of Overtime 6, 9 Hr Days(47H) 6, 9 Hr Days(47H) 6, 10 Hr Days(47H) 6, 10 Hr Days(47H) 7, 8 Hr Days(42H) 7, 8 Hr Days(42H) 7, 9 Hr Days(43H) 7, 9 Hr Days(43H) 6, 12 Hr Days(48H) 6, 12 Hr Days(48H) 7, 10 Hr Days(44H) 7, 10 Hr Days(44H) 7, 12 Hr Days(40H) 7, 12 Hr Days(40H) Pct Productivity Premium / Hr Premium / Hr**** = 29% = 29% = 48% = 48% = 52% = 52% = 74% = 74% = 82% = 82% = 94% = 94% = 166% = 166%

**Premium is the additional cost of overtime, calculating labor at time and 1/2 over 40 hours divided by the equivalent hours

Paying For Overtime

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0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Lunch Only Lunch & 6 Breaks Type of Break Schedule

Percent of Time

Working Time Disguised Breaks Spontaneous Breaks Prescribed Breaks

9.4 9.6 9.8 10 10.2 10.4 10.6 10.8 11 11.2 11.4 Time to Complete One Part (Graf, 1954) (Graf, 1954)

Give me a Break - Please!

Total Parts Produced: 3043 Total Parts Produced: 3114!

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Modelling Relative Risk

(

Folkard & Lombardi, 2004)

We can estimate the Relative Risk for a work

schedule by taking into account:

1.

The length of the shifts (8h, 12h, etc)

Shift Length>8hrs = Higher Risk

2.

The type of shifts (Morning, Night, etc)

Risk of Night > Afternoon > Day

3.

The number of consecutive shifts (“days” in a

row without days off)

Higher Risk with ^ Successive Days (^ for Night Shifts)

4.

The interval between breaks (2h, 4h, etc)

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Sample Schedules

Reference: 8H X 5Days, Breaks Every 2H

1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2 12H X 4 Days 12H X 4 Nights 12H X 5 Days 12H X 5 Nights 10H X 6 Days 10H X 6 Nights Schedule

Estimated Relative Risk (Compared to 8H X 5

Days With Breaks Every Two Hours)

Break Every Hour Break Every 2 Hours Break Every 4 Hours

(48H)

Hours/Schedule: (48H) (60H) (60H) (60H) (60H)

1.78

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Conclusions

1. Simple guidelines based on total

work hours

alone

will be of very

limited use in keeping risk within an

acceptable limit.

2. The interactions of the basic work

scheduling elements must be taken

into account simultaneously.

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Injury Risk Estimation Models

• Liberty Mutual’s Work Scheduling Calculator is

primarily based on Folkard’s identification of good quality injury risk research.

– Currently for use by Liberty Mutual Consultants only; modeling described in Brogmus, 2006 in HFES Annual Meeting Proceedings.

– Designed to provide work scheduling guidance

– Provides the relative risk between two work schedules.

• UK’s HSE (Spencer, et al, and Folkard, et al.) –

Includes risk and fatigue “indices” and allows for entry of exact work schedule (e.g., rotating, non-fixed

schedule shifts, etc.)

– Available online: http://www.hse.gov.uk/research/rrhtm/rr446.htm

– Initially designed to address evaluation requirements of the UK’s Railway (Safety Critical Work) Regulations.

– Provides a “risk index” for a work schedule as compared to a rotating 12h shift with 2 Days on, 2 Nights on, 4 days off.

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Liberty Mutual’s Work

Scheduling Injury Risk Estimator

Pros

• Only 4 Required Inputs • Based Solely on Direct

Injury Research • Graphical Representation of Impact of 1 or 2 Scheduling Factors Simultaneously Cons • Complex Schedules Require Additional Manual Calculations

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HSE (UK) Fatigue and Risk Index

Pros

• Can enter detailed schedule, including complex ones

• Takes into consideration type of work and commuting time

• Incorporates Fatigue Research into Risk Index

• Graphical Representation of the Work Schedule Provided

• Graphical Representation of Risk Index over span of schedule

• Provides separate Fatigue and Risk Indices.

Cons

• Requires detailed schedule input.

• Extrapolates from Fatigue Research and incorporates adjustments and

assumptions on days off and commuting time into Risk Index.

• Provides separate Fatigue and Risk Indices. ABC 001 Day 4, 4, 3, 3 01012007 0.75 0.8 0.85 0.9 0.95 1 1.05 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 Duty Risk Index

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Simple Demonstration

Which Schedule Has Less Risk?

Schedule A:

10 hours/day, 6 days/week, breaks

every 2 hours (60 hours total/week)

Schedule B:

9 hours/night, 5 days/week, breaks

every 3 hours (45 hours total/week)

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Reducing Shift Work Risks

General Design Guidelines

• Day (morning) shifts are to be preferred over afternoon or night shifts. If additional hours are needed to meet production demands, it may be better to add hours to each shift or add an

additional day of work.

• Limit work to 5 or 6 consecutive shifts in a row.

• Schedule work so that all workers have at least two rest days off in a row and that at least one of these days is Saturday or Sunday.

• Alternate weeks of overtime with weeks of normal time.

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• Avoid several days of work followed by 4 to 7 day mini-vacations, e.g., 10 to 14 days of work followed by 5-7 days off. These schedules

should be used when there is no other choice, e.g., mining or oil exploration.

• Keep the schedule regular and predictable. (Studies of train accidents showed that very irregular schedules contributed to the

accidents by producing sleep loss and

fatigue.) Provide workers with 30 days notice for variable schedules.

Reducing Shift Work Risks

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Rest Breaks

•

Provide for frequent rest breaks.

•

Hourly breaks are appropriate for many

kinds of work, but for highly repetitive or

strenuous work, breaks more frequently

than once each hour are necessary.

•

How do your workers know when to

take a break?

•

How do you know if your workers have

taken a break?

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Night Work Guidelines

• Consider alternatives to permanent night

shifts. Most workers never get fully used to night shift work, since they go back to a daytime

schedule during days off.

• Keep consecutive night shifts to a minimum. Only 2 to 4 nights in a row should be worked before a couple of days off.

• Keep night work at an average of 48 hours per

week, allowing up to six 8-hour night shifts or four 12-hour night shifts per week.

• Avoid quick shift changes and adjust shift length to the workload. When changing employees' work

schedules, consider all aspects of the worker's job and home life.

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•

Increase employee awareness and ability to

cope with night work by the need to get

good sleep.

– A good-quality mattress!

– Establishing a sleep routine that works best for the individual including: utility of exercise, diet, and

relaxation techniques to reduce stress.

– Use black-out drapes, turn off phones and pagers, use a fan or white noise source to mask daytime noises. – NIOSH’s publication, Plain Language About Shiftwork

(Rosa and Colligan, 1997 – available for free

download), provides additional helpful practical advice.

Night Work Guidelines (continued)

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Summary

• Research on work scheduling and injury risk is good enough to give DIRECTIONS for improvements, but the limited

scope of some of the research demands CAUTION. • The interaction of different work scheduling factors is

complex enough so that software can help organizations understand the impact of work scheduling on injury risk. • Liberty Mutual and HSE have developed software to help

compare schedules for injury risk, but it is not the whole story in any real-life work situation. Employers MUST consider non-injury implications of work scheduling

decisions such as productivity, overtime pay, and staffing considerations.

• There are many practical improvements that employers can make that can mitigate the effects of alternative work