Fatal Four: Avoiding Construction’s Deadliest Hazards

Construction is one of the most dangerous industries to work in. One out of every five worker deaths last year was in construction, a percentage that has remained fairly constant over the last several years. The four leading causes of construction worker fatalities are falls, electrocutions, being struck by objects and being caught in or between objects. OSHA has dubbed these the “Fatal Four” and in 2014, they accounted for 508 of the 874 construction worker deaths.

The total number of construction fatalities has been on the rise the past couple of years, after declining for six consecutive years which ended in 2012. The fatal injury rate per 100,000 workers has declined the past three years, going from 9.9 in 2012 to 9.7 in 213 and 9.5 in 2014. Construction employment has been on the rise which would account for the rise in total deaths but a slight decline in the fatal injury rates. Employers still need to do a better job of mitigating these four types of hazards to better protect their workers.


Falls are the leading cause of all construction worker deaths. In 2014, they accounted for 348 of the 874 fatalities in construction. Looking at the most cited OSHA standards violations for the construction industry in Fiscal Year 2015 (October 2014 – September 2015) and it’s no surprise that falls were the cause of nearly 40% of all construction worker deaths.

Six of the top 10 most frequently cited violations deal with protecting workers from fall hazards. The top four have consistently been the most cited standards for the past several years. They are:

  1. Standard Number: 1926.501 – Duty to have fall protection.
  2. Standard Number: 1926.451 – General requirements for scaffolds.
  3. Standard Number: 1926.1053 – Ladders.
  4. Standard Number: 1926.503 – Training requirements for fall protection.

The other two that made the top 10 were Standard Number: 1926.453 – Aerial lifts and Standard Number 1926.502 – Fall protection systems criteria and practices at No. 9 and No. 10, respectively.

In construction, fall protection is required for all employees working at a height of six feet or more above a lower level. It is also required when working at any height directly above dangerous machinery or equipment, including impalement hazards such as rebar. There are exceptions to this rule. When working on scaffolds the height for requiring fall protection is 10 feet.

OSHA has outlined three prescribed methods of providing fall protection to workers: guardrails, personal fall arrest systems and safety nets. Of the three, guardrails are the only method that actually prevents falls. The other two methods are designed to prevent a worker who has fallen from coming into contact with a lower level.

Guardrails are typically used on unprotected edges, scaffolds and around openings such as skylights and elevator shafts. The top edge of guardrail systems should be 42 inches (+/- 3 inches) from the walking or working surface. The top rail should be able to withstand 200 pounds of force and the middle rail should be able to withstand 150 pounds of force to prevent falls.

Personal fall arrest systems are made up of three main components: full-body harness, connecting device and anchorage. The minimum breaking strength for connectors, D-rings and snaphooks, and vertical lifelines and lanyards that make up the connecting device is 5,000 pounds for each component. Personal fall arrest systems should prevent a worker from falling any further than six feet and should prevent the worker from making contact with a lower level. Personal fall arrest systems should be inspected before each use and after any fall to ensure they are free of any damage and in proper working order.

Safety nets should not be placed further than 30 feet below a working surface and be positioned as close as possible to the work area. Safety nets must extend a minimum of eight feet out horizontally from the working surface. A minimum breaking strength of 5,000 pounds is required for all border ropes on a safety net. Safety nets must be able to successfully absorb a drop test with a 400-pound bag of sand.

The top three sources of fall fatalities in 2014 were roofs at 30%, ladders at 25% and scaffolding at 16%. Roofers have the highest fatality rate in construction at 46.2 per 100,000 workers. Employers are responsible for providing fall protection, ensuring safe ladder use and ensuring proper scaffold construction designed by a qualified person and overseen by a competent person. Employers are also required to provide adequate training to all employees exposed to fall hazards.


Electrocutions, death by electric shock caused by exposure to lethal amounts of electrical energy, were the second leading cause of construction worker deaths in 2014. Electrocutions accounted for 74 deaths, or 8.5% of all construction worker fatalities. Common causes of electrocutions include improper extension cord use, contact with energized sources and contact with live overhead power lines. De-energizing or simply maintaining a safe distance are the easiest methods to prevent electrocutions from power lines.

The most cited violations in construction that can lead to electrocutions include 1926.405 – Electrical wiring methods, components and equipment for general use; 1926.404 – Electrical wiring and design; 1926.501 – Duty to have fall protection and 1926.413 and 1926.403 which are general requirements regarding equipment and worker protection, respectively.

Employers should establish an assured equipment grounding conductor program to cover all temporary receptacles, power cords and equipment. Detailed records of all tests and inspections. Visually inspect all power tools, equipment and extension cords for cuts, frays and exposed bare wires. Ensure that ground prongs have not been removed or become defective Conduct continuity tests on all equipment grounding conductors.

All receptacle outlets not part of the permanent wiring of the structure are required to be protected by ground-fault circuit interrupters (GFCIs). GFCIs monitor the electrical current flow from hot to neutral and will trip the circuit to shut off the electricity if an imbalance is detected. To avoid accidental electrocution implement lockout/tagout procedures when equipment and circuits are not being used. A qualified person is required to ensure that all equipment and circuits are de-energized before a lock and/or tag is applied. A qualified person should be available when it is time to remove locks and tags and re-energize equipment and circuits.

Death can occur from exposure to as little as 50 – 100 milliamperes of current. The maximum current that a person can grab and release a live wire is only 16 milliamperes, any higher and they will not be able to release their grip. Paralysis of respiratory muscles occurs when exposed to 20 – 30 milliamperes of current. Most 120 Volt circuits carry 15 to 20 amperes of current. 15 amperes of current is 300 times what is necessary to cause death. Other causes of death from electrical hazards include burns, arc flash and blasts, explosions and fires.

Struck by Objects

Being struck by objects was the cause of 73 worker deaths, 8.4% of all construction fatalities in 2014. A wide range of hazards can cause injuries and fatalities, everything from falling tools to accidental nail gun discharges to being hit by vehicles or construction equipment. The four most common struck by hazards in construction: flying objects, falling objects, swinging objects and rolling objects.

Employers should alert all workers of areas where there is greater potential for struck by accidents to occur limit access to those areas. OSHA requires that employers provide employees with proper Personal Protective Equipment (PPE). All PPE should meet current American National Standards Institute (ANSI) standards. OSHA is in the process of issuing a final rule to update their standards on eye and face protection in construction to be more in line with current national consensus and ANSI standards. PPE should be inspected prior to each use to ensure that it’s in proper working condition and free from any defects or damage.

Struck by Rolling Object Hazards – Rolling object hazards typically involve being struck by a vehicle or heavy equipment while it’s in motion. They also include any object that rolls, moves or slides on the same level as a worker. Equipment operators generally have limited or no visibility when operating in reverse. Workers need to be made aware of areas where heavy equipment is being operated so they can avoid them. Struck by accidents involving heavy equipment often occur when operators have not received proper training on how to safely operate the machinery.

Struck by Falling Object Hazards – Falling object injuries typically occur when tools and materials get knocked off from unprotected edges by employees working at height. Employees should be prevented from working or walking in areas where work is being performed overhead. Toeboards and screens should be used to keep tools and equipment from falling to a lower level. Debris nets and catch platforms can be used deflect falling objects.

Struck by Flying Object Hazards – Examples of flying object hazards include thrown tools or materials, accidental nail gun discharges and using unguarded power tools. Workers should stay out of the line of sight when a nail gun is being used. Avoid working on the opposite side of a wall of plywood or sheetrock because misfires have enough force to easily penetrate both materials and kill someone on the other side. Inspect power tools before use to ensure protective guards have not been removed and are in good condition. Workers should always wear eye, face and head protection when using power tools or working near them.

Two of the most cited OSHA violations in construction involve the standards for head protection and eye and face protection. Issuing workers proper PPE and enforcing their use can go a long way in protecting workers from flying and falling hazards.

Struck by Swinging Object Hazards – Swinging object hazards generally occur when something causes loads being mechanically lifted to sway. Accidents can also occur when a worker enters the swing radius of a piece of heavy equipment like a crane. Employees should never be allowed to walk under a suspended load. Barriers should be erected to keep employees from accidently stepping inside the swing radius of heavy equipment.

Caught in or Between Objects

Getting caught in or between objects rounds out the list of OSHA’s Fatal Four. In 2014, they were the cause of only 12 construction worker deaths. These are similar in nature to being struck by objects, the difference being these fatalities are the result of crushing injuries rather than the initial impact. Caught in or between accidents occur when someone is caught, crushed, squeezed, compressed or pinched between two or more objects.

Getting caught in moving parts of machinery and power tools are common types of caught in accidents. Safety guards that are missing or have been intentionally removed are the most likely cause. Loose clothing can get caught in moving parts and pull workers in. Equipment should be de-energized when not in use, especially when making repairs, performing routine maintenance or changing accessories.

Heavy equipment is commonplace on constriction sites and can lull workers into a false sense of security. Never allow workers to place themselves in between a moving vehicle and an immovable object such as a wall. Caught in or between accidents can also occur when you are behind the wheel of heavy equipment. Never overload or overwork a piece of equipment since it can lead to tip overs. Always wear seatbelts or safety restraints when operating equipment. The cabs of those machines are designed and reinforced to protect the worker. Jumping out or being flung out could result in being crushed underneath tipping equipment.

Unprotected trenches and excavations are another leading cause of caught in accidents. Trenches deeper than five feet must have protective systems in place. A professional engineer is required to design protective systems for trenches or excavations over 20 feet deep. Sloping, benching and shoring trenches can be used to prevent collapses. Trench boxes and shields protect workers from being buried alive or crushed by cave-ins.

Heavy equipment should not be used near trenches with workers inside. They can cause cave-ins and even fall into excavations if they get too close to the edge. OSHA requires trenching and excavation work be inspected by a competent person. The competent person must be trained on the requirements of the OSHA standard, the use of protective systems and soil classifications. They are responsible for identifying and eliminating any hazards before workers enter the area and while work is ongoing.

Nearly every accident at the construction site is preventable when proper planning and safety procedures are established. The keys to keeping workers safe are ongoing training, providing proper safety equipment and identifying and eliminating existing and potential hazards. A strong safety program takes work and requires buy-in from all employees. For more information, be sure to check out our 8 Tips To Building A Stellar Safety Program.


4 replies
  1. Drew
    Drew says:

    It’s not surprising what the most common hazards are on the construction site. It might be beneficial to focus safety meetings on these areas to help as much as you can.

    • Kendall Jones
      Kendall Jones says:

      Thanks for the comment, Drew. Totally agree that safety meetings should focus on those hazards when applicable, some sites might not have fall hazards for example. Safety meetings should cover all hazards that exist on the site that day, week, etc. depending on the frequency of safety meetings.

  2. Michael Robinson
    Michael Robinson says:

    Thanks for helping me understand what the most fatal four construction mistakes are and what to look for! I am thinking about going into construction since I was laid off from my most recent job. With that being said, I will make sure to be checking my surroundings at all times. Thanks again!

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