Case Study
Incident and Allegations
A temporary worker had been assigned to assist with operations and maintenance of a recycling machine. During an attempt to clean materials from the bottom, the worker entered the machine's ram chamber. The worker alleged that it unexpectedly activated while he was inside, leading to severe injuries to his foot and hand.
S-E-A was retained by defense counsel representing the facility owner to determine the cause of the injuries and reconstruct the accident. S-E-A was asked to complete a multidisciplinary evaluation of the machine operation/guarding, safety aspects, as well as an analysis of the worker’s actions and decision making. This required mechanical, safety, and human factors expertise.
Investigation & Analysis
To perform the analysis, S-E-A took the following steps:
- The subject machine and pertinent portions of the facility were inspected and documented with measurements, photographs, and 3D laser scans.
- Relevant documents were reviewed, including equipment manuals, company safety procedures, the worker’s employment/training records, and warning labels and signage.
- Accurate 3D models of the recycling machine, worker and surrounding environment were created to demonstrate how the incident unfolded, to evaluate other activities available to the plaintiff, and to analyze alternative procedures proposed by the plaintiff’s expert.
Analysis:
A mechanical analysis was completed to determine if the machine was designed to operate automatically and if it was fully operational. The analysis evaluated all equipment to see if it was in working order, and if any modifications made had any impact on the subject incident. Additionally, the analysis considered if the tools available were adequate to clean the machine, with sufficient reach, or if the worker’s claim that he needed to enter it were accurate.
A safety investigation was performed to evaluate the facility’s Energy Control Safety Program, with an emphasis on lockout/tagout process (LOTO), LOTO training, and company provided LOTO hardware. The facility fell under OSHA 1910 General Industry, and the guidelines in OSHA 1910 subpart J 1910.147 were evaluated.
The human factors analysis evaluated the overall safety communication to determine if it was sufficient and adequate for warning users of the hazards. The worker would have observed multiple “Danger” and “Caution” labels warning against the exact activity undertaken, but there were claims of a failure to warn. Additionally, the area the worker was in was designated conspicuously as a restricted work area. This analysis evaluated the worker’s specific actions and decision making, including risk perception, information-seeking tendencies, evaluation of warnings, and scientific studies on compliance with safety instructions.
Evidence was evaluated resulting in the following findings, among others:
The Mechanical Investigation found that the recycling machine was in good working order and operated as intended. All designed guarding aspects were present, and safety devices were in working order. The worker stated he was required to enter the machine in order to clean it. However, tools were present at the site specifically intended for clearing jams without entering the machine, and S-E-A’s reconstruction showed that the tools were adequate to complete the task without entry into the machine.
The Safety Evaluation concluded that the facility’s written Energy Control Safety Program included energy control procedures for specific equipment, employee training requirements, inspection requirements, and detailed information about the materials and hardware needed to isolate and control hazardous energy (mechanical and electrical). The facility’s LOTO procedures, training, and equipment were compliant with OSHA requirements, and the plaintiff failed to meet his employee obligation outlined in the OSHA General Duty clause. The failure to follow the Energy Control Safety Program allowed the machine to actuate while the worker was in the chamber.
The Human Factors analysis showed that the risk associated with the equipment was highly apparent and properly communicated through signage and training. The four warning signs’ color, size, frequency and placement all met industry standards for readability and conspicuity per Z535.4 standard. S-E-A was able to apply the concepts of information-seeking behavior and metacognition to explain how the behavior of the injured worker was not reasonable. The worker’s disregard of the safety training, procedures, warnings, and instructional information available to him led to the incident, not any deficiency in the machine or established procedures.