Hierarchy of Controls versus Haddon’s 10 Countermeasures
Article by George Robotham – B.Ed. (Adult & Workplace Ed.), Grad. Cert. Management of Organisational Change, Grad. Dip. Occupational Hazard Management.
The traditional wisdom when developing hazard controls is to apply the Hierarchy of Controls-Elimination, Substitution, Engineering, Administrative, Personal Protective Equipment.
I was introduced to Haddon’s Hazard Control Model at Ballarat University many years ago and became quite a fan. Whichever model you use I describe it as putting your thinking into “ boxes “ which allows you to explore options. I have applied both methods personally and by leading teams of supervisors and workers developing controls.
The immediate advantage with the Haddon method is that you have twice as many “boxes” to put your thinking into and are thus able to develop more control options. My experience is that supervisors relate to the terminology in the Haddon model better than the Hierarchy.
If I have a team of people working on developing controls using the Haddon model for the first time I usually give an approximate 30 minute introduction to the technique using examples of the different countermeasures that are relevant to their workplace.
Hazard Control Model
Various hazard control strategies and models have been developed by safety professionals over the years. One of the most effective but still easiest to apply is that devised by American researcher Bill Haddon
Haddon’s model for hazard control is as follows:
|Prevent the marshalling of the form of energy in the first place.
eg. Ripping seams – instead of blasting, substitution of radiation bin level sources with ultra-sonic level detectors, using water based cleaners rather than flammable solvents.
|Countermeasure 2||Reduce the amount of energy marshalled.
eg. Radiation – gauge source strength, explosive store licence requirements, control number of gas cylinders in an area
|Countermeasure 3||Prevent the release of the energy.
eg. handrails on work stations, isolating procedures, most interlock systems
|Countermeasure 4||Modifying the rate or distribution of energy when it is released.
eg. slope of ramps, frangible plugs in gas bottles, seat belts.
|Countermeasure 5||Separate in space or time the energy being released from the susceptible person or structure.
eg. minimum heights for powerlines, divided roads, blasting fuse.
|Countermeasure 6||Interpose a material barrier to stop energy or to attentuate to acceptable levels.
eg. electrical insulation, personal protective equipment, machinery guards, crash barriers
|Countermeasure 7||Modify the contact surface by rounding or softening to minimise damage when energy contacts susceptible body.
eg. round edges on furniture, building bumper bars, padded dashboards in cars.
|Countermeasure 8||Strengthen the structure living or non-living that would otherwise be damaged by the energy exchange.
eg. earthquake and fire resistant buildings, weightlifting.
|Countermeasure 9||To move rapidly to detect and evaluate damage and to counter its continuation and extension.
eg. sprinkler systems, emergency medical care, alarm systems of many types.
|Countermeasure 10||Stabilisation of damage – long term rehabilitative and repair measure.
eg. clean-up procedures, spill disposal, physiotherapy
Generally the larger the amounts of energy involved in relation to the resistance of the structures at risk, the earlier in the countermeasure sequence must the strategy be selected. In many situations where preventative measures are being considered the application of more than one countermeasure may be appropriate.
Countermeasures may be ‘passive’ in that they require no action on the part of persons, or ‘active in the sense that they require some action or co-operation on the part of the persons, perhaps in association with a design related countermeasure (eg. seatbelts).
‘Passive’ countermeasures tend to be more reliable in the long term. A short term solution to an immediate problem may require the adoption of an ‘active’ countermeasure eg. toolbox sessions on replacing guards over a mechanical hazard, the long term or ‘passive’ countermeasure might be the fitting of interlocks to the guard so that power is off when the guard is off.
Haddon, W ‘On the escape of tigers an ecologic note – strategy options in reducing losses in energy damaged people and property’ Technology Review Massachusetts Institute of Technology, 72;7, 44-53, 1970.