Human factors for the design and

operation of mobile equipment

Alison Godwin, PhD Executive Member, Centre for Research in Occupational Safety and Health

Assistant Professor, School of Human Kinetics

Tammy Eger, PhD Director, Centre for Research in Occupational Safety and Health

Associate Professor, School of Human Kinetics

WSN Health of a Miner Symposium

November 12, 2014

Why heavy equipment?

Bulldozer: stiff shoulder, fatigue, LBP

Crane operator: back disorders, vibration

Earth moving: LBP, discomfort, spine

disorders

Forklift: stiff shoulder, LBP, fatigue

Power Shovel operator: stiff shoulder, LBP

Tractor operator: vibration and LBP

Zimmerman Profile of MSD’s

in heavy equipment operators

Longer employed Older equipment

The field of human factors is

concerned with the

interaction between

people and work systems,

in order to maximize

human well-being and system

performance.

Why human factors &

ergonomics?

What are some of the concerns

with heavy equipment operation?

Line-of-sight and visual field

Seating quality

Cabin space

Control layouts

Ingress and egress

Work scheduling

Poor LOS is a cause for concern

Loaders, haul trucks and other heavy equipment are often involved in

accidents due to poor LOS

Heavy equipment operators are at increased risk for back and neck

musculoskeletal disorders

Large Machines and Line-of-Sight

Pedestrian

The pedestrian is no longer visible

What DOESN’T an

operator see?

Pick-up Truck

Recent Coroner’s Inquests

(Ontario, Canada)

recommend renewed focus

on LOS and earth moving

equipment (2009, 2010)

Machine Components and LOS

Cab Design (posts & windows)

Light Posts/Brackets

Bucket size

Engine profile

Machine Design Impacts LOS

Driving posture during

LHD operation has neck rotated more than 45⁰ for over 89% of the shift

Limits for awkward neck postures have been documented by only a few sources:

Swedish National Injury Criteria (Eklund et al. 1994)

• Neck should not be rotated >45deg for more than 50% of the shift. Suggested Neck Postures (Gellerstedt et al. 1999)

• Operators should not be required to rotate head <30deg. • Operators should not have to tilt head > 5deg upwards or >25deg downwards.

LHD Operator Posture & LOS

Seat adjustability Seat height

Seat angle

Seat swivel

Cabin space

Improve line of sight

Enhance mirrors or camera use

Reduce postural requirements

Coroner’s Inquest Recommendations

Posture Variables

8.26 7.71 6.25

19.4 17.714.9

42.638.7

31.1

0

10

20

30

40

50

0 20 45

Seat Rotation (degrees)

Po

stu

re C

rite

ria

(de

gre

es

)

Trunk Lateral Bend Trunk Rotation Neck Rotation

Seat rotation resulted in significantly less

trunk lateral bend, trunk rotation and neck

rotation.

0 degrees

45 degrees

Seat Rotation

666666666666666666666 Kittusamy Ergonomic Checklist for

Cab Design on Construction

Machinery

Seat adjustability factors

Armrest adjustability factors

Vibration overview

Cab space interacts with

design features

Dynamic armrest by

Michele Oliver

University of Guelph

* Pictures from Murphy and Oliver, 2011 **Patent pending

666666666666666666666 Kittusamy Ergonomic Checklist for

Cab Design on Construction

Machinery

Seat adjustability

Controls factors

Environment factors

Visibility factors

Ingress/Egress

Visibility factors

Cab Space ISO 3411:2007 Earth-moving machinery -- Physical dimensions of operators and minimum operator space envelope Provides the dimensions of operators of earth-moving machinery and specifies the minimum normal operating space envelope within the operator enclosures.

ISO 6682:1986 Earth-moving machinery -- Zones of comfort and reach for controls Defines zones of comfort and reach for controls derived from the overlapping reach capability of large and small operators in the seated position. Is intended as a guide for the design of the operator compartment controls for earth-moving machinery

Seat Adjustment

ISO 11112:1995 Earth-moving machinery -- Operator's seat -- Dimensions and requirements Specifies the dimensions, requirements and adjustment ranges for operator seats on earth-moving machinery. Additionally, it contains dimensions for armrests when fitted on these machines

Seat Features

Miller and Gariepy, 2011

Environmental: Cab

Temperature consistency

Temperature distribution

Loudness of alarm

Type of alarm (frequency, tone, etc)

Ventilation concern

ISO/CD 1996-2 Acoustics -- Description, measurement and assessment of environmental noise -- Part 2: Determination of environmental noise levels

http://www.volvoce.com/SiteCollectionDocuments/VCE/Documents%20North%20America/backhoe%20loaders/bl60b-bl70b%20product%20brochure.pdf

Ingress and Egress

Ingress/Egress

Ingress/Egress

EMESRT Design Philosophies

DP – 1 Access and Working at Heights www.51933.activeboard.com

Controls and Displays

ISO for Controls and Displays

ISO 6011:2003 Earth-moving machinery - Visual display of machine operation Specifies the machine operation functional information to be presented by the visual displays of earth-moving machinery for a seated operator.

ISO 6405-1:2004 Earth-moving machinery -- Symbols for operator controls and other displays -- Part 1: Common symbols ISO 6405-2:1993 Earth-moving machinery -- Symbols for operator controls and other displays -- Part 2: Specific symbols for machines, equipment and accessories The symbols given apply to controls and displays specific to backhoe loaders, dozers, loaders, graders, scrapers, excavators and dumpers, and for controls and displays for stabilizers, outriggers, grapples, rippers and winches.

Controls &

Displays

Checklist Items to Consider

Protection against movements

Controls activate functions according to figures

Controls follow directional compatibility

Primary controls within the comfortable zone

Secondary controls within reach zone (no excessive movement)

Control adjustability desirable

Location of visual displays within 30⁰ cone of operator position

Legible displays in all lighting conditions

EMESRT Design Philosophies for

Controls

From DP – 5 Machine Operation Controls

Other Resources

EMESRT Design Philosophies for

Displays

From DP – 5 Machine Operation Controls

Testing Control Layouts (Steiner et al. 2013)

Resource

http://www.crcpress.com/product/isbn/9781439802311

Final Thoughts

Although we have presented many of the challenges with heavy equipment design in isolation – the issues are often more complex and interrelated.

Reducing adverse health effects associated with mobile equipment operation (poor LOS, awkward postures; whole-body vibration exposure;controls/displays; ingress/egress) will require a multifaceted approach involving participation of workers, industry leaders, equipment manufacturers, and researchers.

Questions?

Industry Partners Workplace Safety North Ontario Mining Industry Northern Ontario Steel Manufacturing Industry

Research Partners Dr. Paul-Emile Boileau, IRSST (Montreal, QC) Dr. James Dickey, University of Western Ontario Dr. Michele Oliver, University of Guelph Dr. Joan Stevenson, Queen’s University Graduate and undergraduate RA students

Acknowledgements

Funding Agencies

For more information contact: Tammy Eger, Ph.D. (teger@laurentian.ca)

&

Alison Godwin, Ph.D. (agodwin@laurentian.ca)

Centre for Research in Occupational Safety and Health

Laurentian University

Ramsey Lake Road, Sudbury, ON, Canada, P3E 2C6

Web: www.crosh.ca

Twitter: @crosh_crsst

CROSH Centre for Research in Occupational Safety and Health

www.CROSH.ca

@CROSH_CRSST

For more information:

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Heavy Mobile Equipment - Ergonomics and the Prevention ofMusculoskeletal Injuries. Linda Miller, EWI Works International Inc. and Claire Gariepy, EWI

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