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Written By: Joseph Sampedro
August 29, 2025
A jobsite is a dynamic environment, filled with powerful machinery, heavy materials, and complex tasks. While this energy drives progress, it also harbors inherent risks. Among the most serious of these are struck-by hazards.
You can't always see them coming. A tool dropped from above, a piece of debris from a grinder, a vehicle backing up—these events happen in a split second, but their consequences can be devastating. The Occupational Safety and Health Administration (OSHA) recognizes struck-by incidents as one of its "Fatal Four" leading causes of death in the construction industry, alongside falls, electrocutions, and caught-in/between hazards. This isn't just a statistic; it's a call to action.
Understanding these dangers is the first step toward eliminating them. This article will serve as a comprehensive guide to identifying the different types of struck-by hazards, exploring the real-world scenarios where they occur, and detailing the multi-layered safety protocols we should implement to ensure every member of our team goes home safely at the end of every single day. A safe project isn't an accident; it's the result of deliberate planning, constant vigilance, and an unwavering commitment from every person on site.
Deconstructing the Danger: The Four Categories of Struck-By Incidents
To effectively combat a threat, you must first understand it. Struck-by hazards are not a single type of event; they are a broad category of incidents that OSHA breaks down into four distinct types. Each has its own unique causes, risk factors, and, most importantly, prevention strategies.
1. Struck-By Flying Objects
A flying object hazard exists when an object has been thrown, hurled, discharged, or propelled through the air. The source of injury is the object's momentum. This is one of the most common types of struck-by incidents, often resulting from the use of power tools or the handling of materials in windy conditions.
Real-World Scenarios:
Power Tools: A worker using a grinder without a proper guard can send sparks and metal fragments flying. A nail from a pneumatic nail gun can ricochet off a hard surface. A saw blade can catch and eject a piece of wood with incredible force.
Pressurized Equipment: Debris can be launched from equipment during pressure washing or when a high-pressure hose fails.
Environmental Factors: Strong winds can turn unsecured lightweight materials, like sheet metal or insulation panels, into dangerous projectiles.
Core Prevention Strategies: The primary defense against flying objects is containing the energy at its source and protecting the individual. This involves always using guards on power tools, ensuring pneumatic tools are not fired unless the nose is in contact with the work surface, and securing materials on windy days. Critically, mandatory eye and face protection, such as safety glasses with side shields or full-face shields, provides a final, essential barrier.
2. Struck-By Falling Objects
This hazard is defined by any object falling from a higher level and striking a person below. Gravity is the force multiplier here, meaning even a small object like a bolt or a tape measure can cause a catastrophic injury when dropped from a significant height. This risk is ever-present in multi-story construction and maintenance work on scaffolding, lifts, or rooftops.
Real-World Scenarios:
Work at Heights: A worker on a scaffold accidentally kicks a wrench off the platform. A hammer is left unsecured on top of a stepladder and falls.
Material Handling: A load of bricks is improperly secured on a forklift and a brick falls from the pallet. During a crane lift, a component of the rigging fails.
Demolition: Debris from a wall being demolished falls onto a worker on a lower level.
Core Prevention Strategies: Preventing falling objects requires a systematic approach. Enforce the use of toe boards, screens, and guardrails on all scaffolding and elevated platforms. Tool tethers and lanyards are required for anyone working at heights. Establish clearly marked "No-Go" zones below overhead work using barricades and warning signs. Large-scale projects may utilize debris netting to catch falling materials. Crucially, no one is ever permitted to work or walk directly underneath an active overhead load.
3. Struck-By Swinging Objects
A swinging object hazard occurs when materials or equipment move, sway, pivot, or twist. This often involves mechanically lifted loads but can also include swinging doors or gates. The danger zone is the entire radius of the swinging object.
Real-World Scenarios:
Crane and Hoist Operations: A crane lifts a load of steel beams, and as it swings to place them, the load sways unexpectedly.
Heavy Equipment: An excavator or backhoe operator swings the machine's bucket to dig or move earth, creating a large danger zone.
Material Handling: A worker guiding a suspended load with their hands can be crushed if the load shifts.
Core Prevention Strategies: Rigorous planning and communication are key. Lift plans are developed for all crane operations. Only qualified and certified riggers and signal persons are used. Taglines are used to guide loads from a safe distance, preventing workers from placing their hands directly on the object. The swing radius of all heavy equipment must be clearly barricaded, and clear communication between the operator and ground personnel is mandatory at all times.
4. Struck-By Rolling Objects
This category includes any object that is rolling, moving, or sliding on the same level as a worker. This most commonly involves vehicles and heavy equipment, but it also applies to unsecured materials on a sloped surface.
Real-World Scenarios:
Vehicles and Equipment: A forklift reverses without a spotter in a busy warehouse. A truck backs up, and its audible alarm is non-functional or drowned out by other site noise. A worker is caught between a vehicle and a fixed wall.
Unsecured Materials: A heavy pipe or cylinder stored on an uneven surface begins to roll. A pallet jack left on a slight incline starts to move.
Core Prevention Strategies: A comprehensive traffic control plan is essential on any site with vehicle traffic. This includes designated walkways for pedestrians and clear routes for vehicles. All vehicles must have functioning backup alarms, and spotters are required for any equipment operating in tight quarters or with obstructed views. Furthermore, all materials must be chocked, blocked, or properly racked to prevent unintended movement.
The Blueprint for Prevention: A Multi-Layered Safety Strategy
True safety goes beyond simply reacting to hazards. It’s about proactively building a system where incidents are prevented before they can ever occur. We achieve this through a multi-layered strategy that combines the right equipment, intelligent work design, and a well-trained, vigilant team.
The Foundation: Personal Protective Equipment (PPE)
PPE is the last line of defense, but it is a non-negotiable and life-saving one. Don’t just provide PPE; ensure it's the correct type for the task and that your team is trained on its proper use and maintenance.
Head Protection: Hard hats are designed to deflect blows from falling objects and protect against impacts with fixed structures.
Eye and Face Protection: Safety glasses with side shields are good for eye protection. However, tasks like grinding, cutting, or handling chemicals demand higher protection like goggles or full-face shields.
High-Visibility Clothing: Being seen is being safe. All personnel on jobsites should wear high-visibility vests or shirts to ensure they stand out against the complex background of a jobsite, especially to equipment operators.
Protective Footwear: Steel or composite-toed boots are essential to protect against rolling objects or dropped tools. Puncture-resistant soles add another layer of protection from sharp debris on the ground.
Engineering Controls: Designing Safety Into the Worksite
The most effective way to prevent a hazard is to physically remove it from the workspace. This is the principle behind engineering controls. Instead of relying solely on worker behavior, modify the environment itself to make it inherently safer.
Guarding: All moving parts on machinery and tools, such as belts, gears, and blades, must be equipped with physical guards.
Physical Barriers: Use guardrails, barriers, and fencing to physically prevent workers from entering hazardous areas, such as the swing radius of a crane or an open excavation.
Protective Structures: On demolition projects, build canopies or protective shields over walkways to protect personnel from falling debris.
Administrative Controls: Safe Work Practices and Procedures
This layer involves the rules, procedures, and practices that govern how work is performed on sites.
Pre-Task Safety Briefings: Every day, and before every new major task, gather the team for "Toolbox Talks" to discuss the specific hazards they will face and the control measures in place.
Regular Inspections: All tools, equipment, and rigging must be inspected regularly by competent personnel to identify and correct defects before they can cause an incident.
Controlled Access Zones: Establish and clearly mark zones where specific hazards exist, such as overhead work areas or lifting zones, and restrict access to only essential personnel.
A Culture of Safety
Ultimately, rules and equipment are only as effective as the people using them. That's why the final, and most important, layer of our safety program is fostering a deep-rooted Culture of Safety.
This culture is built on the belief that safety is a shared responsibility. It means empowering every single employee, from the newest apprentice to the most senior manager, with Stop Work Authority. If any member of our team sees an unsafe condition or feels a task cannot be done safely, they have the absolute authority and obligation to stop the work until the hazard is resolved, without fear of reprisal.
A safe project is a sign of a well-managed, professional, and high-quality operation. It demonstrates respect for employees, clients, and the community. We must understand that our work is only as good as the safety of the people who perform it. Diligently identify risks, proactively implement controls, and continuously improve safety systems to ensure that struck-by incidents—and all other jobsite hazards—remain what they ought to be: entirely preventable.
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