Fatality Assessment and Control Evaluation (FACE) Program
Guardrail Post Pounder Operator Electrocuted When Hammer Boom Contacts Energized Overhead Electrical Line
On November 6, 2002, a 23-year old male operator of a guardrail post pounder mounted on a stake truck was electrocuted when the boom of the post pounder contacted an energized overhead power line. The state highway was oriented in a north/south direction. The contract required guardrails on the highway’s east and west sides as well as guardrail placement on the south side of an intersecting road. The company had notified MISS DIG and all underground utility lines were marked. The guardrails on the west side of the highway had been set and the employees were placing guardrails on the east side. It was very windy on the day of the incident causing the overhead lines to sway in the wind. Work had progressed between 150-200 feet along the highway shoulder when, while pounding the guardrail post, the boom contacted an energized overhead 14,000 volt power line that crossed the highway in an east-west direction. The contact energized the truck and the victim received a fatal shock. He fell, breaking contact. Coworkers heard “crackling” and looked over toward the post pounder truck. They saw the victim lying on the ground, under the truck. They carefully pulled him clear from the energized truck and called for emergency responders. The victim was declared dead at the incident scene.
On November 6, 2002 a 23-year old male post punch machine operator was electrocuted while he was placing guardrail posts into the ground. On November 12, 2002, MIFACE investigators were informed by Michigan Occupational Safety and Health Act (MIOSHA) personnel, who had received a report on their 24 hour-a-day hotline, that a work-related fatal injury had occurred on November 6, 2003. On May 7, 2003 the MIFACE researcher visited the company headquarters and interviewed the co-owners. At this location, the guardrail post pounder truck was also seen. After visiting the company location, the researcher traveled to the incident location. During the course of writing the report, the autopsy results, police report and the MIOSHA citations were obtained. Photographs used for Figure 1 and Figure 5 were taken at the time of the incident by the responding police agency. The MIFACE researcher took the photographs used in Figures 2, 3, 4 and 6.
The company received two alleged willful/serious violations. One citation was for the failure to develop an Accident Prevention Program; no specific instruction to employees, no record of inspection procedures to eliminate recognized hazards, no designated person to administer the company’s safety program. Also contained within this citation was that there was no training in Safety standards or common practices by the company’s type of work operations (industry practices). The second alleged willful/serious violation was that the employer did not maintain proper clearance of a power line crossing work area. Employees were operating a guardrail post pounder truck with the truck boom approximately 22 feet high. The overhead power line voltage was 14,000 volts. The company received a Repeat Serious alleged violation for employee failure to wear a hard hat while operating and assisting the operator of the guardrail post pounder. The company also received two alleged violation designated as other. One citation was for failing to notify the Department of Consumer and Industry Services of a fatal employee injury within 8 hours. The second citation was that the Form 300 for 2002 was incomplete.
The company has approximately 20 employees and has been in business for approximately 5 years. The company installs guardrails. The victim was an hourly, full-time employee, and had been employed with the company for 4 years. His job title was the post pounder truck operator. He was a member of the union. The company was a site subcontractor. The individual experienced a non-fatal electrocution using the same piece of equipment approximately 3 months earlier and required hospitalization for his injuries. At the time of the fatality, the company did not have a written accident program. The post pounder truck was purchased used without an operator’s manual. The company did truck maintenance.
A few days prior to the incident, the company owner talked with the victim about job safety, using the equipment safely, and about the dangers posed by overhead power lines. The supervisor on site is responsible for site safety. Employees have the authority to correct on-site safety hazards they see; if they cannot correct the hazard, they are instructed to call the office for assistance in abating the hazard.
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The hydraulically powered guardrail post pounder was mounted on a stake truck. It had a gravity drop hammer and turntable. The boom had a working height of 22 feet. The truck was referred to as the “post pounder” (See Figure 1). The operator (victim) could remotely drive the truck while walking on the ground alongside the truck by activating control levers at the operator station. The victim had approximately 8 months experience operating the post pounder; he operated it on a daily basis when placing rails. The victim was required to wear a hard hat while operating the post pounder. He was not required to wear other personal protective equipment.
The job crew consisted of one foreman, one post punch operator (the victim) and 4 laborers. The crew worked 10- hour days, 5 days a week. The company was contracted to place guardrails on the east/west shoulders of a state highway as well as installation of guardrail on the south shoulder of an intersecting road. The company had been at the job site for 2-3 weeks. To construct a guardrail, the victim would position a steel H-beam approximately 6 feet in length in a vertical position into the post pounder boom below a cable operated hammer device. The victim, standing on the ground at the operator controls, would activate levers to drive the beam into the ground along the road shoulder. After setting the beam, he walked alongside the truck, moving it to the next location to set the next steel beam. Other company employees would follow him and install the guardrail onto the newly set steel beams. (See Figure 3)
Prior to beginning work, the company had contacted MISS DIG and all underground lines were marked. The company did not indicate to MISS DIG that overhead power lines were in the area. The electrical lines contacted were oriented in an east/west direction and traveled across the highway.
The company had completed installation of the guardrail on the west side of the highway; the section of guardrail on the west side did not extend underneath the overhead lines. (See Figure 4). The ground was icy and snow covered. It was a windy on the day of the incident, and the emergency responders noted that the overhead line was moving back and forth in the wind. The victim was setting the steel beams along the east shoulder. He had set beams approximately 150-200 feet, moving the post pounder in a southerly direction. The post pounder truck cab was facing south.
The boom was extended upward when it contacted the overhead power line. It is unknown if the victim was walking alongside the post pounder or if he was setting a beam when the overhead power line contacted the boom. The boom extended approximately one foot above the wire and approximately 4-6 inches from the wire. (See Figure 5)
When the energized wire touched the raised boom, electric current arced into the post pounder. The victim was holding the left control lever with his left hand when the electrical current struck him; he acted as a path to ground. The left lever control was bent from the impact of his reaction to the electricity. (See Figure 6). He fell to the ground, landing under the truck, breaking contact with the electricity. His coworkers, working on a separate task at the time of the incident, did not witness the electrocution. They heard a “crackling” sound and looked over and saw the victim on the ground by the rear of the truck. A coworker pulled him from under the energized truck and began CPR. Another employee ran to the foreman who was approximately 1/4 mile away to get help. Emergency assistance arrived and transported him to the nearest hospital where he was dead on arrival.
There were burn marks on the boom on the side toward the cab. Before the truck was moved to a safe area, the electrical company was contacted and their employees insulated the wire.
Company employees, in retrospect, indicated they thought the electrical line looked low. Several days later when they went back to the job site to complete the guardrail installation, they thought the lines had been raised.
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Cause of Death
The cause of death as listed by the medical examiner on the death certificate was death by accidental electrocution from a high voltage electrical line. Toxicological results were negative.
Conduct a jobsite survey (hazard assessment) to identify potential hazards before starting any job and implement appropriate control measures.
Prior to the start of work, employers should conduct jobsite surveys to identify potential worker hazards so that appropriate preventive measures to control these hazards can be identified and implemented. Two characteristics of this jobsite combined to produce a serious hazard: 1) a 14,400 V energized overhead power line located approximately 22 feet off the ground and, 2) the use of a conductive truck-mounted boom in the vicinity of the power line. Such potential hazards can be minimized by ensuring that employees maintain a safe distance from energized conductors, by providing employees with non-conductive tools and materials, and /or by de-energizing or covering electrical conductors with insulating material. In this case, neither the foreman or the operator apparently considered the height of the mast when fully raised when assessing the hazards during the guardrail post installation. A safety checklist should be developed as part of a standard operating procedure to conduct the jobsite analysis. This should be used prior to the start of any activity at the work site.
The location of the machine (directly below the power line) and the weather conditions (overcast and windy) may have interfered with the operator’s perception of distance to the power line. Where applicable, a person should be designated to observe clearance of the equipment and give timely warning for operations where it is difficult for the operator to maintain desired clearances by visual means.