Struck-by Hazards

Worker being struck-by a box
Does it appear the impact of the box falling on the worker will cause the injury? If so, then the worker was "struck-by" the box.


There are actually two types of struck hazards: Struck-by and Struck-against. In either type, the injury is produced by forcible contact or impact between the injured person and an object or piece of equipment.

  • In a Struck-by accident, the object strikes the worker.
  • In a Struck-against accident, the worker strikes the object.

In this module, we'll focus on Struck-by hazards because they occur more frequently and are one of OSHA's Focus-Four hazard types. One in four "struck by vehicle" deaths involve construction workers, more than any other occupation. It is important to point out that in construction, struck-by hazards can resemble caught-in or -between hazards.

To determine whether an event is a Caught event or a Struck event, ask yourself: Was it the impact of the object alone that caused the injury?

When the impact alone creates the injury, the event is considered as "Struck" event. On the other hand, when the injury is created more as a result of crushing injuries between objects, the event is considered as "Caught."

Struck-by hazards are categorized as follows:

  • struck by flying object
  • struck by falling object
  • struck by swinging object
  • stuck by rolling object

1. When the impact alone causes an injury, the accident is considered a _____ event.

a. contact
b. crush
c. struck
d. caught

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Construction crew working on a road.
Construction workers must always be aware of the vehicles around them.

Struck-by hazards in construction cause accidents such as the following:

  • Four workers were installing signs on a highway when a pick-up truck changed several lanes and entered the work area. The truck struck one of the workers, knocking him off the road and over a bridge rail. He fell approximately 18 feet and died.
  • Four workers were struck by an exterior wall while attempting to lift it in place. Three of the workers received bruises and contusions. One of the workers received a fractured leg and was hospitalized.
  • A construction inspector was crossing an equipment vehicle route at an interstate highway bridge construction site. He walked into the path of the end loader traveling the route, was run over, and killed. The loader operator was unaware that he struck the inspector.
  • A worker was struck by the counterweight and revolving superstructure of an excavator when he walked between the excavator and a hillside.
  • Workers were pulling 60-foot sections of pipe out of a hole, using a hoist to stack them on the derrick floor. One of the workers let go of a pipe section before it was secured. As he bent over, the pipe swung around and struck him on the head, killing him.
  • A worker was maneuvering an overhead crane when a metal plate, weighing approximately 7,330 lbs., separated from the lifting clamp and fell, striking and killing the worker.

2. Which of the following is considered a Struck-by accident?

a. A worker runs into a metal column
b. A metal plate falls on a worker
c. A worker is pulled into a chipper
d. A worker falls to a lower level

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Struck by Flying Objects

Workers inspecting a nail gun and the nail gun is pointed at one of the workers.
Is the worker on the right at risk of being struck by a nail? If the worker on the left doesn't handle his nail gun safely, is he at risk as well?

Flying object hazard exists when something has been thrown, hurled, or is being propelled through space. It can include instances when a piece of material separates from a tool, machine or other equipment, striking a worker, resulting in injuries or fatalities.

Also, a hazard exists if an object is ejected under power by a tool or equipment. Examples include:

  • A nail gun, probably the tool causing the greatest number of serious injuries on the construction site, propels a nail from the gun by force. This force can be either pneumatic or powder-actuated.
  • A bench grinder may cause injury when a disintegrating wheel strikes a worker. In Oregon, USA, some years ago, a worker was killed when a chunk of a broken grinder wheel hit his femoral artery in his upper leg.

Powder-actuated tools are particularly hazardous due to the force behind the fastener. These fasteners are designed to go through wood, concrete and steel, and they can certainly go through a worker. To learn more about nail gun safety, see course 611 Nail Gun Safety.

Using compressed air can also cause flying object hazards. Compressed air is commonly used to power tools and clean surfaces.

Practice Identifying Hazards

Try to identify the hazards in each picture below. Then click on each picture to see if you correctly identified the hazards.

Struck-by Flying Objects Hazard
Click to review hazards
Struck-by Flying Objects Hazard
Click to review hazards

3. Which power tool is most frequently the cause of a serious Struck-by injury or fatality?

a. Nail gun
b. Drill
c. Sander
d. Saw

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Struck by Falling Objects

You are at risk from falling objects when you are directly beneath cranes, scaffolds, or overhead work being performed, etc. Injuries can range from minor abrasions to concussions, blindness, or death.


  • A worker was tearing down a transmission structure using a digger-derrick when a pole broke and struck him on the head.
  • A worker was struck by a load of wall panels that fell off his truck.
  • Four workers rebuilding a bridge that had washed out by floods were injured when a crane boom cable broke, and the boom fell on them.
  • A worker was engaged in cutting an 8,000-lb boiler in sections with a cutting torch. The section being cut fell off allowing the remaining 5000-lb section, to flip over onto its bottom and land on the worker.
  • A worker was assisting a rigger who had attached a load to the block hook of a wheel mounted crane. The crane operator was positioned in the cab and waiting for the hand signal to make the lift. During this process, the jib of the crane fell from its stowed position on the boom and struck the worker. The worker died later at the scene. It was discovered that the pin used to secure the jib to the boom was missing thus allowing the jib to be displaced. The crane was not inspected prior to use.

Practice Identifying Hazards

Try to identify the hazards in each picture below. Then click on each picture to see if you correctly identified the hazards.

Struck-by Falling Objects Hazard
Click to review hazards
Struck-by Falling Objects Hazard
Click to review hazards

4. In which situation is a worker most likely to be struck by a falling object?

a. walking by a suspended load
b. working under others using hand tools directly overhead
c. working on the first floor under a safety net
d. working on a roof installing vents

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Struck by Swinging Objects

Crane lifting a cement plant.
When working around cranes a worker must always be aware of the hazards that exist.

When the source of injury has been referred to objects that are not free standing, they are attached at some point or are being held by the worker. This includes instances where a hinge-like motion retracts creating swinging motion in which the worker is struck-by a slamming or swinging motion.

When materials are mechanically lifted, they have the potential to swing and strike workers. As the load is lifted, the materials may swing, twist or turn.

This movement can catch workers by surprise, and the swinging load could hit them. Windy conditions are especially hazardous because the load will swing more. Depending on where the worker is standing and the force behind the load, the worker may fall to another level after being struck and sustain even greater injuries. In addition to swinging, loads can slip from their riggings and strike workers. Loads must be rigged properly to prevent slipage.

Practice Identifying Hazards

Try to identify the hazards in the picture below. Then click on the picture to see if you correctly identified the hazards.

Crane lifting load.
Click to review hazards

5. What is an especially hazardous condition that makes being struck by swinging objects more likely?

a. Size and shape of a load
b. Windy conditions
c. Hoisted loads with tag line
d. The weight of the load

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Struck by Rolling Object

Struck-by rolling object is when an object is rolling, moving, or sliding on the same level at which the worker is located. It includes instances in which the worker is struck or run over by a moving vehicle without being caught under it or instances in which the worker is struck-by a sliding object or equipment on the same level.


Worker picking up traffic cones in street.
Working around traffic is extremely dangerous.
  • While walking along the track, a worker was struck by an unmanned rail car at an airport.
  • A worker (security guard) was struck by a tractor trailer and dragged, resulting in fatal injuries.
  • A worker suffered fatal injuries after being struck by a moving semi-truck while loading/unloading freight.
  • A worker was performing repair operations on an impact attenuator and was struck by a truck.
  • A worker was flagging traffic and was struck by a truck.
  • A four-person ground crew was working with a mobile under-hung bridge crane. The crane ran over one of the crew members, who had walked too close to the wheel of the crane. The employee died from his injuries.
  • A worker was setting traffic cones for a paving project. A steel wheel roller was compressing the asphalt, and the traffic cones were being moved so that they would be in the path of the roller. The worker was injured when he was struck by an automobile. He was thrown over the hood of the car and into another lane of traffic, where he was struck by another automobile. He was dragged 141 ft by the second vehicle. He was pronounced dead at the hospital.

Practice Identifying Hazards

Try to identify the hazards in each picture below. Then click on each picture to see if you correctly identified the hazards.

Pinned between
Click to review hazards

6. What type of Fatal-Four hazard is most likely to cause injuries or fatalities to workers exposed to traffic on a construction site?

a. Struck by flying objects
b. Struck by falling objects
c. Struck by rolling objects
d. Struck by stationary objects

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