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Course 808: Focus Four - Struck-By Hazards

Safety guides and audits to make your job as a safety professional easier

What is a Struck-by Hazard?


Struck-by injuries are produced by forcible contact or impact between the injured person and an object or piece of equipment. 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. 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

Check out this short audio clip by Dan Clark of the Not wearing a hard hat can kill. A tape measure fell 50 stories. A man, whose hard hat was in his truck, died. This avoidable death happened Monday, November 3rd, 2014, in New Jersey. Dan gives the painful details, and urges workers to wear their PPE.


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.

Watch this video for more information on PPE:

Skylight a worker fell through


Occupational fatalities caused by struck-by hazards are a serious concern. According to the Bureau of Labor Statistics (BLS) 2013 preliminary data, the category of "Contact with objects" is 16% of the total 4,405 fatal work injuries. Of that, the sub-category of "Struck-by object" was 11% (more than two thirds).

In the table below, the 2008 numbers are given for "Crane-Related Deaths" which show when working with cranes, the struck-by death and injury count represents 28% of the total.

Causes of Construction Worker Crane-Related Deaths & Injuries, Jan. 1–Dec. 31, 2008*

Cause # Incidents Deaths Injuries
Crane collapses 34 (39%) 25 59
Overhead power line contacts 12 (14%) 10 8
Struck by crane load 12 (14%) 6 10
Struck by other crane parts 10 (11%) 6 7
Other causes* 20 (23%) 7 16
Total 88 54 100

* Includes 7 highway incidents, 6 falls, 3 caught in/between, 3 struck by non-crane falling objects and 1 struck by lightning incident

Struck-by Flying Object

Major Hazards:

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 fatality.

Also, a hazard exists if an object is ejected under power by a tool or equipment. An example of this would be a nail gun, which propels a nail from the gun by force; it is discharged. This force can be either pneumatic or powder-actuated. 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, click here.

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 image to review hazards

Struck-by Flying Objects Hazard
Click image to review hazards

Struck-by Flying Objects Hazard
Click image to review hazards

Let’s review an example of an actual accident:

Examples of accidents that can result from struck-by flying object hazards:
  • A worker was removing a frozen bolt from the track of a caterpillar front end loader and was struck-by a bolt that entered his forehead.
  • A worker was freeing a pump component under pressure and was impaled by the pump component.
  • A worker was killed when a blast of compressed air from a gas pipeline struck him. A compressor was started to fill the pipeline with compressed air in an effort to push out a "pig." when the pipeline suddenly cleared, an employee was still in the way and was killed. Before the compressor was started the area should have been cleared.
  • The victim was in the process of using an 8-foot step ladder to gain height to nail a strap onto a residential home single story construction project. The victim used a nail gun with a 3 ½ inch nail to affix the strap to the exterior wall. Using his right hand for the gun, he leaned over to the left and tried to place a nail into the strap. The nail ricocheted and hit him on the left side of his head just above the left ear. He fell to the ground and eventually passed out. Fellow workers transported him to the hospital. He died approximately two days later.

Fall from tilt-up concrete wall

Description of Accident

A carpenter apprentice was killed when he was struck in the head by a nail that was fired from a powder-actuated tool. The tool operator, while attempting to anchor a plywood form in preparation for pouring a concrete wall, fired the gun causing the nail to pass through the hollow wall. The nail traveled some twenty-seven feet before striking the victim. The tool operator had never received training in the proper use of the tool, and none of the employees in the area was wearing personal protective equipment.

What would you recommend?


  • Institute a program for frequent and regular inspections of the job site, materials, and equipment by a competent person(s) (1926.20(b)(2)).
  • Require employees exposed to the potential hazards associated with flying nails to use appropriate personal protective equipment. (1926.100(a) and 1926.102(a)(1)).
  • Train employees using powder actuated tools in the safe operation of the particular tool (1926.302(e)(2)).
  • Train employees operating powder actuated tools to avoid firing into easily penetrated materials (1926.302(e)(8)).

Struck-by Falling Object

Major Hazards:

A person is struck-by a falling object when crushed, pinned, or caught under an object that has fallen from above. This does not include the collapse of material or structures.


  • 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.

Read about a real-world accident

Fall from tilt-up concrete wall

Description of Accident

Ball and socket connectors are used to attach conductor stringing blocks to insulators on the arms of 90-foot metal towers of electrical transmission lines. Normally stainless steel cotter keys secure the ball and socket connector in place. In this case, however, black electrical tape was wrapped around the socket to keep the ball in place rather than a cotter key. The tape apparently stretched, and the ball came loose, dropping the stringing block approximately 90 feet onto the head of an employee below, one of a four-man erection crew.

What would you recommend?


  • Rigging and equipment must be regularly inspected and maintained in safe operating condition as required by general provisions of OSHA's construction (29 CFR 1926.959).
  • Employees must be instructed to recognize and avoid unsafe conditions. They must also be made aware of regulations that apply to the work and the work area, which eliminate safety and health hazards as required in the safety training and education section of OSHA's construction safety standards (29 CFR 1926.21(b)(2)).

Struck-by Swinging Object

Major Hazards:

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.

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.


  • A worker was working within the swing radius of a barge-mounted crane used in dredging operations. He was hit and killed.
  • Two workers were instructed by their foreman to set up on a ground slab in the southeastern corner of a building. They were to land and place reinforcing steel using a crane. A truck crane was positioned at street level; 30 ft higher in elevation than the ground slab and approximately 162 ft from the landing area. The landing area was approximately 40 ft beyond the radius limit for the crane, as specified by the manufacturer. The 24 piece bundle of 28 1/2 ft long #9 rebar that was to be picked up and loaded onto the crane's hoist line was at street elevation, 50 ft in front of the crane. The operator made the pick-up and was swinging around and lowering it to his left using hand signals when the right pennant line broke at the yoke/bridle. The boom collapsed, striking one of the workers on the head and killing him.

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.

Struck-by Rolling Object

Major hazards:

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.
  • 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.


Before beginning this quiz, we highly recommend you review the module material. This quiz is designed to allow you to self-check your comprehension of the module content, but only focuses on key concepts and ideas.

Read each question carefully. Select the best answer, even if more than one answer seems possible. You must answer all of the questions before submitting the quiz.

Good luck!

1. Struck-by injuries are caused by _____.

2. When the impact alone creates the injury, the event is considered as _____.

3. When an injury is created more as a result of crushing injuries between objects, the event is considered as _____.

4. Struck-by hazards are categorized by which four different types of objects?

5. When materials are mechanically lifted, they have the potential to _____ and strike workers.

Stay safe!

Important! You will receive an "error" message unless all questions are answered.