As problem solvers, we tend to get way ahead of ourselves. We tend to go for solutions before we totally understand the causes, problems and the systems in which they exist.
This is the problem when we seek to solve slip, trip and fall injuries. Some of our roadblocks come from the paradigm that solving these injuries is easy. Posting signs, quickly cleaning up messes, telling employees to be more careful or specifying safety shoe soles to wear, commonly is our easy way to deal with these problems, but all are totally ineffective solutions.
Perhaps our desire to make slip, trip and fall injuries go away is rooted in our propensity to grab for quick solutions when we don’t understand what the many causes and factors are and what we are trying to improve. slip, trip and fall injuries go away is rooted in our propensity to grab for quick solutions when we don’t understand what the many causes and factors are and what we are trying to improve.
So, let’s take a deeper look at the causes and factors of slip, trip and fall injuries. Taking this “mile-deep-and-inch-wide” look will help us see why adopting new rules for effectively preventing these injuries makes sense.
The static coefficient of friction (SCOF), or the measure of slip-resistance commonly is espoused as gospel but grossly misunderstood because we equate SCOF with a measure like handrail height or a PEL.
In reality, slip-resistance is highly variable both by how it is measured (if there is a need to measure it) and what truly is safe or unsafe because our lines for determining safe slip-resistance are anything but bright.
Let’s talk about slip-resistance testing first. Factually, there is no clear testing method for slip-resistance. The English tribometer is thought by a lot of floor safety experts to be the preferred method of testing for slip-resistance, but the drag or pull meter, as an example, widely is used and gives good results.
The important thing for us to understand is that the variation in testing results of any slip-resistance testing methods is high, perhaps less with the drag meter, for example, because of the size of the floor area actually tested. The English tribometer, in its testing method, strikes the walking surface and each test or strike hits an area of about one square centimeter or less where a drag instrument tests an area around three square inches, depending on the meter used. So, variation in testing results can change by just moving the point tested a centimeter or inch.
Also consider that the line that is supposed to identify what is safe and unsafe is broad if you consider the commonly-accepted SCOF limit of 0.5 as the standard. This is why other countries and business sectors have adopted higher SCOF limits.
All other slip and trip system factors and interrelated issues must be taken into account, especially testing variation. So, this is why many slip experts have been moving away from espousing the importance of or from focusing on measures of slip-resistance as input into solving slip hazard problems.
As those who commonly are called on to say of something is hazardous or not, a murky line doesn’t help us. So, how can we resolve this conundrum?
If we get our heads out of the exactness, the dependence on measures and data, finding a bright line can be easy if we use a legal line, those regarding known hazardous conditions.
Let’s quickly identify some known hazardous slip conditions that really require no slip-resistance testing, as exactness isn’t helpful and only can add to the argument. Conditions that are known to be hazardous and thereby require correction and even more importantly, prevention include:
- Ice on any walking surface, especially black ice that cannot be easily seen
- Any lubricant or surfactant on a walking surface, regardless of the texture of that surface, that significantly reduces the slip-resistance;
- Water, or any liquid or fleshy material on a surface that is non-porous or sealed or polished, such as linoleum, marble, hardwood, ceramic tile or even highly smoothed and polished concrete;
- Wet materials that are transient in form like wet paint or remnants from cleaning up, mopping, etc. and
- Any industry- or process-specific material that is spilled and is known within the industry or business sector to be slick.
We as safety practitioners depend way too much on people seeing things as a means to preventing injury. So, understanding the mechanics of walking is extremely important for us and not just the muscle, momentum and balance mechanics, but more importantly first, the control mechanics of walking.
We commonly forget how we walk when we quickly try to problem-solve slip and fall injuries. It seems so obvious that people slip and trip when walking, yet we move to solving the problems before we understand the mechanics that contributed to the fall.
If you rose to your feet and walked to get a cup of coffee or to look out a window or to have a conversation, do you remember the foot travel you just took? If you are “normal,” that is, walk like 99.995 percent of people, you don’t.
We are wired to place as much “regular” or “routine” things we do under autonomic control, because our brains understand that it would be exhausting to do everything under totally conscious control. Walking is that way as well as driving a car, or eating a meal, reaching for a child or turning on a TV or computer. We do about 90 to 95 percent of our routine things autonomically; we don’t even think about the details of how we do them or when we do them. We direct our minds to well-known tasks, and we do them without much conscious thought.
Why is this important for us to know and consider when we seek to prevent slip and trip injuries? Because if we miss things or hazards, in this quick subconsciously-controlled scan, or if a hazard has become “normal” so that it raises no flags nor connects us to our consciousness, the hazard or potential consequence of that hazard becomes invisible and we are at an elevated state to be impacted by it or them.
The second reason is that just because a hazard is “open and obvious”, we can’t rely on a person’s safety awareness to be a factor in injury prevention. The fact is, if we don’t see it, or recognize that it is a hazard, or if the hazard becomes normal “noise” in our environment or from our experiences, our awareness becomes disassociated from risk.
So, how do we move into and out of conscious control of our walking, because once you unconsciously hand-off control of your walking mechanics to autonomic-reflex, post the starting scan for hazards, your brain and senses don’t merely check-out for the duration of the walk? Our brains are marvelous organs and the interaction that our brains have with subtle things we sense, goes on constantly. So, if we hear something that is unexpected or our eyes detect something that is again, not normal, our brains immediately kick back into conscious mode, and normally, by reflex, we stop or alter our walking path.
Why is knowing this important? First, it tells us the power of visual cues for helping us see hazards and avoiding them. The second reason is so that we can know that, whereas visual cues are great in the short term, even highly-visible cues can become invisible as they become “normal landscape.” In our normal pre-walk scan for hazards, they too can become invisible over time.
A trip simply is when a foot that is moving forward suddenly confronts an unexpected obstacle or resistance. We understand, I hope, the elevated trip hazards that a single rise in walking surface, a single step, creates, because tripping against a single step has a exponentially greater risk than a set of stairs. However, small changes in walking surface elevations create even greater risks.
Again, consider the mechanics of walking, but this time, foot swing, that part of walking when one foot leaves the walking surface as your body momentum moves forward and becomes elevated in a swing-arc to a forward position so that it can be the next foot-plant and provide a stable foundation for the next step.
All foot swing-arcs are not created equal, and the height of that foot off the walking surface can be affected by many things including the velocity we travel. Also of importance is whether the front of the shoe sole being worn has a slanted or curved leading surface or a hard leading sole (toe) angle that more easily can catch on edges.
The height of a normal foot swing-arc at mid-point only is about a half inch above the walking surface, give or take a quarter or three-eighths of an inch. Because of the normal mechanics of foot swing, very small rises in walking surface heights can be extremely hazardous.
The Accessibility Standards of the Americans with Disabilities Act recommends that a surface with no greater rise than one-quarter of an inch exist. Also, unexpected changes in walking surface slip-resistance can cause trips, such as going from a slicker surface to a carpet or rug.
Why is this important? Knowing this should cause us more closely to look at seemingly small and insignificant rises in walking surfaces, and significant changes in slip-resistance are important considerations for trip-prevention improvements.
Other Risk Factors
If you want to see the entire system that produces slip, trip and fall injuries, you must consider the other factors that not only contribute to a person’s susceptibility for slip and trip hazards and the resulting fall, but also are significant factors that tend to make the extent of injuries from a fall, costs and the recovery times more or less. Those factors are:
- Physical conditioning
- Inner ear or other balance issues
- Physical conditioning
- Area/process familiarity where they are subjected to slip and fall hazards
- The velocity that the worker is traveling when he/she encounters the hazard
- Process or job complexity
- Exertion or applied forces
- Whether or not there are second fall hazards like from one level to another
- Carrying objects that can block views or intended foot placement
- Objects or other hazards that the worker can fall against.
Comprehensive slip, trip and fall assessments for creating effective fall prevention improvements must consider all of these factors. It is a convenient strategy to construct a simple “fall factors” checklist to create a process that will always be followed in an assessment.
Effectively preventing slip and fall injuries requires building a more in-depth knowledge of the many parts of the system that produces the injuries. It also requires that we reject simple solutions like placing the emphasis on awareness, putting up signs or requiring special shoes.
The point for us is prevention, which means removing the causes of the slips, trips and falls in the first place and not accepting the easy road or attempting to minimize the extent of injury or pass the blame back to the person.
About the author: F. David Pierce holds a master’s degree in industrial hygiene from the University of Utah and multiple safety and health certifications. He has published five books on safety management and over 100 articles. He currently resides in Salt Lake City and in principle consultant in Leadership Solutions Consultants Inc.