Struck-By Hazards in Construction: Flying, Falling, Swinging, and Rolling Objects

Picture a normal day on site. Equipment is running, tools are going, crews are working at height, loads are being hoisted, and trucks are moving in and out of the gate. Every one of those activities can put an object in motion, and when that object hits a person, OSHA calls it a struck-by incident.

Struck-by is one of the Focus Four hazards, along with falls, electrocution, and caught-in/between. Together those four cause most construction deaths. Struck-by incidents are also very preventable once you learn to see them coming.

Struck-by vs. caught-in/between

People mix these two up, and so do test questions. The difference comes down to how the injury happens:

• Struck-by: the injury comes from impact, when something hits you.
• Caught-in/between: the injury comes from being squeezed, pinched, or compressed, as when you get pinned between a machine and a wall.

If a load swings into a worker, that’s struck-by. If the same load pins the worker against a column, that’s caught-between.

The four types of struck-by hazards

OSHA sorts struck-by hazards by how the striking object moves:

Type	How it moves	Jobsite examples
Flying	Thrown or propelled through the air	Loose hammer head, fragments from a mushroomed chisel, nail gun fasteners
Falling	Drops from a higher level onto someone below	Brick off a scaffold, crane jib after a bolt fails, pipe sliding off a truck
Swinging	Swings, twists, or turns into someone	Excavator arm, a hoisted load caught by wind, a load slipping from its rigging
Rolling	Rolls or slides into someone at the same level	Site traffic, dump trucks, bulldozers, graders

Falling objects can do more than hit you. They can also crush and pin you. Wind makes swinging-object incidents more likely, so pay extra attention when it picks up during a lift.

PPE: your personal struck-by shield

Engineering controls and safe work practices come first, but for struck-by hazards your PPE does a lot of the work. Under 29 CFR 1926 Subpart E, your employer has to provide appropriate PPE, keep it maintained, replace it when it’s worn or damaged, and train you to use and care for it. For struck-by hazards, these four items matter most:

• Head protection (1926.100): Wear it anywhere you could be hit by falling or flying objects or bump into beams and piping. Check it for dents, cracks, and deterioration every time you put it on. If a hard hat has taken a heavy blow, replace it even if it looks fine, because it can’t absorb a second impact the same way.
• Eye and face protection (1926.102): Wear safety glasses or goggles for welding, cutting, grinding, and nailing, and on windy days when dust is blowing. A face shield alone doesn’t fully protect your eyes, so always wear glasses or goggles under the shield.
• Foot protection (1926.96): Steel-toe boots protect your toes from impact and compression. Metatarsal guards or boots with built-in metatarsal protection cover the small bones on top of your foot.
• High-visibility clothing: Drivers and operators avoid hitting the people they can see. Wear reflective hi-vis gear whenever vehicles or equipment are moving.

Remember: Never wear damaged PPE. If it’s cracked, dented, or has already taken a hit, take it out of service and get a replacement.

For a full rundown of PPE from head to toe, see our guide on PPE on the jobsite.

Vehicle traffic and backovers

According to the training video, construction workers make up about a quarter of all workers killed by vehicles on the job. That’s why traffic planning should start before any ground is broken. Safe routes get marked with signs, barricades, and cones, and flaggers may direct traffic. OSHA covers signs, signals, and barricades in Subpart G (1926.200–1926.203).

Your site will give you its own traffic training. On any site, these habits apply:

1. Stay alert. Know what’s moving on and around the site.
2. Look both ways every time you cross a haul road or travel path.
3. Keep an escape route. Never put yourself somewhere you can’t get out of a vehicle’s path.
4. Be visible. Wear hi-vis and stay out of drivers’ blind spots.

Don’t trust the backup alarm

Many vehicle strikes happen when the vehicle is backing up, usually because the driver can’t see behind them. Under 1926.601 and 1926.602, vehicles and earthmoving equipment with an obstructed rear view generally need a working reverse alarm or an observer who signals that it’s safe to back up. An alarm is not a guarantee, though:

• Site noise can drown it out.
• It may be broken.
• The vehicle may not have one.

Never cross behind a machine that’s backing up. If a spotter is guiding the operator, make sure the spotter knows where you are. Spotters and flaggers get trained on proper signals, so don’t step in and wave someone back yourself.

Heavy equipment and the swing radius

The training video says about 75% of construction struck-by incidents involve heavy equipment. Unlike a truck on a haul road, heavy equipment can hit you while it’s parked in one spot. Booms swing, and on many machines the whole superstructure rotates.

The ground those parts sweep over is the swing radius, and it’s a struck-by danger zone. Sites often barricade it, but you shouldn’t wait for barricades to tell you where it is.

• Identify swing hazards yourself and stay out of the zone.
• Never work under a suspended load, and stay clear of loads that are being raised.
• Approach every machine with caution, whether it’s running or not. Never come from its blind side.
• Make eye contact with the operator so you know they’ve seen you.

Hand and power tools: flying-object factories

A damaged or misused tool can turn into a projectile. Hand and power tool requirements are in Subpart I. Inspect every hand tool before you use it, and look for:

• Splintered or cracked handles
• Loose heads that could fly off
• Mushroomed heads on chisels, punches, and other struck tools
• Loose or sprung jaws on wrenches

Check power tools to make sure every guard is in place and working. Don’t run a tool you haven’t been trained on, and follow the manufacturer’s instructions.

Compressed air: OSHA limits air used for cleaning to less than 30 psi (1926.302(b)(4)). Wear eye protection even at that pressure.

Nail guns and powder-actuated tools: Get trained before you use one, and get licensed too if your site requires it. Test the tool before use and fix any problem right away. Under 1926.302(e), powder-actuated tools must not be loaded until just before firing, and a loaded tool must never be left unattended.

We cover tool inspections in more depth in Hand and Power Tool Safety.

Special situations

Concrete and masonry walls (Subpart Q)

Walls under construction are heavy enough that anything falling, rolling, or swinging from them can kill.

• Control or turn over reinforcing wire mesh as it’s unrolled so it can’t spring back.
• Don’t place loads on concrete until someone has determined the structure can carry them (1926.701(a)).
• Shore or brace masonry walls until permanent supports are in place.
• Keep your distance from walls going up unless you’re on the crew building them.

Overhead work

Anything dropped from a scaffold, roof, or deck becomes a falling object for whoever is below. Under 1926.501(c) and the toeboard requirements in 1926.502(j):

• Equip elevated surfaces with guardrails, screens, and toeboards.
• Install debris nets below the work level where needed.
• Secure your tools and keep the work area clear.
• Post warning signs and barricade the danger zone below.
• Wear head protection whenever you work under overhead jobs.

Material storage (Subpart H)

Stack sheetrock, lumber, block, and cement bags so they can’t slip, slide, roll, or fall, and take extra care on windy days. In buildings under construction, keep materials at least 6 feet from hoistways and floor openings (1926.250(b)(1)). That way a stack that gets bumped won’t fall to the level below.

Tip: On an OSHA 10 quiz, struck-by questions often hinge on the object’s direction of travel. Ask yourself whether it was flying, falling, swinging, or rolling, then pick the control that addresses that motion.

Quick review

• Struck-by is one of the Focus Four, the leading causes of construction deaths.
• Objects strike by flying, falling, swinging, or rolling.
• Keep your distance from traffic and equipment, and never get behind a backing machine.
• Stay out of the swing radius, and never work under a suspended load.
• Inspect tools before use and wear eye protection.
• Wear head protection around any overhead work.
• Stack materials securely and keep them away from edges and openings.

If you’re new to the trade, read Construction Site Safety Basics next to see how struck-by fits with the other hazards you’ll run into on day one.

How SafePath OSHA Fits Into This

Struck-by is one of the core topics on your OSHA 10-Hour Construction course, and test questions often ask you to classify hazards and pick the right control. The SafePath OSHA 10 app has 1,000 practice questions across all 8 outreach topics, including the full Focus Four, PPE, health hazards, and stairways & ladders. It uses real jobsite hazard photos so you practice spotting struck-by situations the way they look on site, and all of the content is available in Spanish.

The full SafePath suite has 2,200+ questions across 2 apps, so if you move up to supervising a crew later, the OSHA 30 app is there for you. Start with the free PPE practice quiz or browse all the free quizzes.

Remember: Prep apps get you ready for class. They don’t replace it. Only an authorized OSHA Outreach trainer can issue your Department of Labor card.