OSHA's Fatal Four: What is a Struck-by Hazard?
What Are the Fatal Four?
OSHA's Fatal Four – also called the Focus Four – are the top four categories of hazards that cause construction industry fatalities.
The Fatal Four are:
- Caught-In or Between
Most construction worker deaths (60+%) can be attributed to the Fatal Four. OSHA is understandably focused on these hazards as a result.
According to The Center for Construction Research and Training, more than half of Focus Four fatalities are caused by falls to a lower level, making that the most common cause of death among construction personnel. The second-most common cause is struck-by incidents. They accounted for 17.2% of construction deaths in 2018 and 15.4% in 2019.
What Is a Struck-By Hazard?
The simplest way to explain the definition of a struck-by hazard is, unfortunately, self-referential. It's a hazard that may result in a struck-by injury.
We're not being coy – it's just one thing that is easier to understand than to put into words.
Let's start here: a struck-by injury is produced by forcible contact or impact between a person and an object (often, in construction, equipment or tools). But struck-by injuries are closely related to another of OSHA's Fatal Four – caught-in or between injuries. A "struck" event may result in a "caught" event, so separating the two is a bit tricky.
If the impact of an object alone causes an injury, it's a struck-by injury.
If an injury is more the result of being crushed between two objects, it's a caught-in or between injury, even if the crushing was proceeded by being struck.
What Are the Four Common Types of Struck-By Hazards?
How many categories of struck-by hazards are there? Basically, four.
The primary way to categorize struck-by hazards is according to the striking object's movement. Construction workers can be:
- Struck by a flying object
- Struck by a falling object
- Struck by a swinging object
- Struck by a rolling object
But the type of object is also a critical piece of information.
Especially since approximately 75% of struck-by fatalities involve heavy equipment (including vehicles).
In fact, getting hit by a vehicle is such a common phenomenon in construction that construction workers account for one in four workplace "struck by vehicle" deaths. More than any other occupation.
Examples of Struck-By Hazards
Examples of struck-by hazards include circumstances that put workers at risk of being struck by:
- A moving vehicle or piece of heavy equipment
- Improperly stacked materials that slide, tip over, or collapse
- Flying particles during an abrasive or cutting process
- An improperly controlled power tool
- A load of materials mid-transport
- Materials that are falling due to rigging failure
- Tools or materials dropped by someone working on a higher level
- Another person falling off a higher level
- Compressed air
- A nail from a nail gun
- An improperly braced or shored-up structure that collapses
OSHA Struck-By Hazards: What Are the Standards?
As you can see from the examples above, many potential struck-by hazards lurking around a construction site. So it makes sense that no standard covers OSHA struck-by hazards.
Since three in four struck-by fatalities involve heavy equipment, standards relevant to safety have many rules built in to protect workers from being struck by all or part of a vehicle.
The Signs, Signals, and Barricades standard (§1926 Subpart G) is particularly relevant to struck-by hazards. It requires:
- Warning signs to alert new site entrants of potential hazards
- Temporary traffic control during road construction to reduce the risk posed by civilian vehicles
- Flaggers wearing warning garments which use various safety devices and signs to control civilian and work traffic
- Crane and hoist signals (incorporated from ANSI) that allow work to be directed by someone on the ground
The Motor Vehicle standard (§1926.601) covers off-highway sites not open to public traffic. There are many requirements to prevent struck-by accidents, including:
- Pre-shift vehicle inspections to ensure that all parts and accessories are in safe working condition
- Warning requirements for vehicles with an obstructed rear view (like a backup alarm)
- Precautions for vehicles with dumping or lifting devices
- Wheel chocks for heavy equipment parked on an incline
- Cab shields or canopies to protect the driver on cars that are loaded by crane etc
- Warning garments appropriate for the level of light to make ground personnel more visible
Similar and additional requirements exist in other sections of §1926 Subpart O for materials-handling equipment, pile driving equipment, equipment fitted with swinging booms or slings, and more.
Cranes are another significant source of heavy equipment struck-by incidents. The standard for cranes and derricks (§1926 Subpart CC) includes sections on signals, work area control, keeping clear of the load, controlled load lowering, and hoisting personnel.
Of course, there are also standards designed to prevent struck-by incidents that don't include heavy equipment. These include standards for:
- Materials handling, storage, use, and disposal (§1926 Subpart H)
- Scaffolds (§1926 Subpart L), mainly falling object protection (§1926.451(h))
- Personal Protective Equipment (PPE) (§1926 Subpart E), especially head protection (§1926.100) and eye/face protection (§1926.102)
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