Qualitative methods for occupational risk prevention strategies in safety

Paul Swuste

Safety Science Group, Delft University of Technology

The Netherlands

Topics

Control Bandingprinciples of Control Banding

Models of accident causationSwiss cheeseBow-tiecentral events

Vertical lifting of loadscentral eventsbarrier failures

Control Banding and Safety

Principles of Control Banding

You measure: hazard indication, exposure scenario’s

You compare: banding principles

You control: banding principles

Swiss cheese, Reason 1997

Wrong decision

Wrongdesign

Deviatingconditions

Wrongaction

Wrongaction

Wrongaction

Accident

Blame

Swiss cheese, blame

Bow tie model

and

and

or

F1

F3F4

F5

F7

F8

F2F9

F6

and

and

or

F1

F3F4

F5

F7

F8

F2F9

F6

F10

F11

F12

F13

F10

F11

F12

F13

F10

F11

F12

F13

People

Equipment

Reputation

Environment

F11

F12

F13

Central event

Fault tree, scenario’s and primary barriers Event tree, scenario and effect reducing barriers

Henri Riviere, Tour Eiffel, 1902

Central events, 13.000 accidents, 1998-2003

1. Falling from heights

2. Contact with moving parts of fixed machinery

3. Contact with falling objects

4. Stuck by vehicle

5. Loss of control in or on moving vehicles

6. Contact with hoisted, hanging, swinging objects

7. Contact with object a person in holding, using, carrying

8. Contact with handheld tools

9. Contact of moving person against object

10. Contact with charged objects

11. Loss of control of hazardous chemicals

Central events of crane operations (n=174)

Instability load 72 %

Contact counter weight, or jib 11 %

Instability crane 7 %

Instability hoisting gear 5 %

Instability jib 3 %

Barrier failures, instability load

Safety barriers (hardware)• Improper connection load, equipment failure• Failing load securing mechanism, killer hook

Management factors• Improper connection, motivation• Improper connection, competence failure• Ground location failure, communication failure• Substandard external conditions (big blue)

Control Banding and Safety

You measure: list of central events, scenario’s

You compare: frequency rates

You control: banding principles (?)

Small Sized Enterprises