Energy – Pathway – Barriers
When thinking about causation and how people get hurt, one has to realize that it’s all about Energy Release and/or Not Having Enough of our Essential Energy needs met. People get hurt when the amount of energy they need to sustain their lives (Oxygen, Warmth, Water, and Food) isn’t available. We also get killed or injured when an energy that is larger/stronger than our bodies’ capacity to withstand it hits us.
Let’s focus on the un-supplied Energy needs for a minute. It’s said in the “Rule of Threes” that humans can live 3 minutes without Oxygen, only 3 days without water and 3 weeks without food. As a generalization it solidifies the idea that we need these three things to survive. If our work puts us into a situation of no oxygen (Confined Space Entry) or no water or food (stranded in the desert or on the ocean in a life raft) we will predictably and surely die. So if we’re to be safe and manage our risks we need to at the very least ensure our essentials of life are provided for. There are people on our planet entirely focused on finding water for themselves and their family today…and every day. It’s essential for their existence. My guess is that if you are reading this you are one of the very lucky ones who isn’t doing this.
Enough Energy to Hurt Us
The second part of the Energy theory is that people are injured when an energy that is large enough to go “past our body’s capacity to withstand it” hits us. This contact of BIG energy is what causes our injury. The list of Energies we are exposed to is pretty universal.
1. Mechanical Energy
2. Electrical Energy
3. Chemical Energy
4. Kinetic Energy
5. Potential (Stored) Energy
6. Thermal Energy
7. Acoustic Energy
8. Radiant Energy
9. Atmospheric/ Geological/ Oceanographic Energy
10. Biological Hazards
Not all energy is large enough to cause us a problem. Our bodies are built to withstand a certain level of exposure to most things in our lives. A bit of thermal energy is ok…a lot is not. A bit of sunshine doesn’t create a sunburn but a lot does. A small electrical charge won’t hurt us. That’s why you can put your tongue on the two poles of a 9 volt battery and not die, but don’t try this with the white and black wires of your 110 volt electrical house wiring.
So, in this model, energy needs to be large enough to be a problem otherwise it’s not a threat to your health or safety.
Finding Its Way to You or Your Things
So energy needs to come in contact with you or the thing that will be damaged to be any concern to us at all. We call that process finding a Pathway. Electricity in the wall behind a properly designed wall cover (it is called a Barrier…we’ll get to that) is only a problem if there is a Pathway created from the source to you. Many of us have experienced creating that Pathway unintentionally or intentionally. In North America many children have stuck a thing (fork, knife, safety pin) into the 110 volt socket just to see what would happen. Fortunately most of us live through it and live to NOT do it again. Sometimes we walk right into the energy, sometimes the barrier breaks exposing us to the harmful energy. Sometimes the energy is released by someone else’s actions or inactions. The Pathway can be managed in some ways. The best way is not to create a possibility.
Don’t Touch the “Spinny” Thing
Finally we get to the subtitle. My wife and I live on an acreage. It’s a small “executive size” just under three acres. One of those acres is landscaped with trees, bushes, rock gardens and LAWN. This requires me to mow the lawn and in the winter plow/snow blow the snow from the driveway. The only real solution to these challenges was for us to buy a tractor capable of doing these tasks through the various attachments available. My 23 horsepower diesel Massey Ferguson tractor was purchased with a snow blower, a 5 foot three blade mower and a blade for plowing. I bought this tractor from a friend who is in the business and that friend also knows that I am a musician and has many times seen me play in my band (this will all make sense eventually). Now I have up to this point in my life operated a variety of powered mobile equipment (forklifts, cranes, track mobiles, trucks etc.) so operating equipment wasn’t going to be a new experience. I however have never owned a piece of equipment anything like this tractor since I was “city born and raised.” The day my tractor arrived, my friend came with the delivery truck and personally handed me the keys to my new red tractor and said, “Congratulations Al on your new tractor…be careful of the PTO.” Some of you reading this will know that a PTO is a Power Take-off. The term basically refers to the mechanical devise which “takes power off” a power device. In the case of my tractor the power device is the diesel engine and the gears and shafts on the attachments are the way in which the power is “taken off.”
So with my friends warning to me about the PTO, I couldn’t resist making a bit of a joke of it by saying, “I know what BTO is (referring to the rock band Bachman Turner Overdrive).” Then I asked “What is a PTO?” My friend quickly responded, “It is the spinny thing, don’t touch it.”
A study of farm safety tells us that far too many farmers are guilty of and have been injured by their equipment’s PTOs. After this memorable exchange, the Energy/Barrier model’s pathway became crystal clear to me. Human behaviour often puts us in a place where we actually create the pathway.
Eliminate to Manage Risk
In the hierarchy of controls used to manage hazards (energies) elimination is always the most effective treatment. When faced with a hazard and we can remove the hazard altogether, logically the risk has gone away.
The hierarchy of hazard controls are, in order of decreasing effectiveness are usually described as:
5. Personal protective equipment
In our energy barrier model if we can eliminate the energy or substituted it for less powerful energy we are indeed producing the risk our workers face.
Remove or Move the Target
In the Energy/Barrier Model, the target of the energy travelling the pathway is usually the person or thing we are trying to protect from the harmful energy. Strategies that manage risk by moving the person away from the energy or the energy away from the person are classic in our risk management processes. Simply moving the human away from the energy source can have the effect of eliminating or minimizing the risk. Obviously the opposite is true where we placed the energy far from humans. This management of proximity between humans and energy sources is a very effective way of managing risk and making our work safer.
When All Else Fails Add Barriers
There are times when our work or play puts us in very close proximity to harmful energy. In this model seen in Figure 1 there are two opportunities first place barriers to minimize and/or deflect the harmful energies from hitting the target. Some of the most effective barriers we can put in place are those place closest to the energy source. These have the effect of containing the energy. Typical examples of these barriers include guards, ergonomic designs, and warning signs. Theories need not be only physical things they can indeed be knowledge base. In the example above, “don’t touch the spinny thing” was a warning from my friend in increasing my knowledge of the dangers present. This is a very valuable barrier and works as long as I’m compliant with the warning. In examples of the use of barriers usually “more is better.” Obviously we can take this to an extreme and put so many barriers in place that getting our jobs done is impractical. In the case of those things we do for recreation and play, putting too many barriers in place would take the fun of our activity.
According to Erik Hollnagel – Barriers and Accident Prevention, the following type of barriers are available to us:
· Material barriers – physically prevents an action from being carried out, or prevents the consequences from spreading
· Functional (active or dynamic) barriers – hinders the action via preconditions (logical, physical, temporal) and interlocks (passwords, synchronization, locks)
· Symbolic barriers (perceptual, conceptual barriers) – requires an act of interpretation to work, i.e. an intelligent and perceiving agent (signs, signals alarms, warnings)
· Immaterial barriers (non-material barriers) – not physically present in the situation, rely on internalized knowledge (rules, restrictions, laws)
Personal Protective Equipment
The second opportunity to put barriers in place is close to the person or thing we are protecting. Classic examples of personal protective equipment fall into this category. In this case the reason it is the least effective is we have let the energy come very close to the protected person or thing. In fact, all we’re really doing is reducing the impact of the energy and having that energy strike the personal protective equipment rather than the human. Five mile an hour bumpers that we’ve engineered on our cars is a perfect example of reducing the damage of an impact. The energy actually has to hit our bumpers to make the design work. If the energy is too large, the bumper will not protect the rest of our vehicle.
Safety Is All About Not Letting Energy Hit Us
If you look at the many classes of personal protective equipment you’ll find all they’re really doing is hardening the target or filtering out/deflecting the energy that is already there. This is why personal protective equipment is the least effective of all hazard management strategies.
So there you have it, the Energy Barriers Model recognizes that we are hurt when energy hits us or we don’t have the energies available to us that sustain our health and life. When we’re managing safety through the physical or the behavioral it important to always analyze what we’ve done to reduce the chances of the energy barrier model ruining our day.