As we have already written before, falling objects are one of the most frequent and dangerous risks in industrial jobs, especially in tasks carried out at height.
These types of accidents can cause serious injuries, equipment damage, and operational disruptions, affecting both safety and productivity. Tools, materials or structural components can become detached for a variety of reasons, such as clamping failures, weather conditions or human error.
One aspect that aggravates this risk is that the trajectory of falling objects is not always linear.
Although we tend to imagine that they fall directly to the ground, many objects can be deflected when impacting structures, equipment, or even people, significantly increasing the dangerous area.
This unpredictable behavior means that prevention and control systems must go beyond traditional measures.
Impact of Irregular Trajectories
- Injuries can occur outside of the initially demarcated risk areas.
- Bouncing objects can cause additional damage to critical equipment or infrastructure.
- It is more difficult to design effective containment measures when the object's path cannot be predicted.
Calculating exclusion zones
At the end of this article, we leave you with a calculation tool that was developed by Energy Safety Canada.
It is a response to queries raised about the possible deviation and trajectory of a falling object if it hits a structural element before touching the ground or roof.
This tool has been designed to educate the industry about the use and limitations of exclusion zones and the need for other preventive barriers to build failover security capability.
It is designed to work in conjunction with the DropsOnline.org DROPS Calculator.
It is ideal for applications where suitable exclusion zones can be established that are not limited by the design and layout of existing infrastructure or equipment, such as elevated work platforms, construction scaffolding, etc.
This tool does not determine the probability of a deflection (e.g., impact scaffolding), but rather the probability that an object may initially hit the ground after a deflection on a round surface.
For example, the distance of the 75th percentile means that 75% of objects that drift on a round surface will land within this distance. As such, deflections on other surfaces, such as angle steel on a derrick, will generate different probability distributions; Therefore, determining exclusion zones with this tool in such environments may not be appropriate.
Limitations
This tool is based on the following assumptions:
- An impact occurs at height (deflection),
- The object is a sphere that does not rotate,
- Static fall (no initial vertical or horizontal movement),
- Elastic collision (no loss of energy),
- Just a deflection,
- The deflection surface is round, like scaffold tubes or railings,
- The radius of the deflection surface is small in relation to the drop height,
- No air resistance is assumed (terminal velocity impacts and any navigational effects are cancelled) and
- The projected distance represents the impact with the ground and is therefore not the final resting distance.
In the case of impact on hard ground surfaces, such as metal or elastic materials such as rubber, the fallen object may bounce or slide beyond the intended distance.