Air elevator accidents: operator or machine?
Summary
The journal of occupational health and safety reviewed frequent causes of accidents: when aerial elevators are used, noting that accidents due to operator error and misuse have increased as aerial elevators have become more common with customers. 2002
Reprinted with permission from the september issue of occupational health & safety, (c) stevens publishing corporation.
Learn how regulations and standards are enforced. Osha regulations prohibit employers from forcing workers to use unsafe equipment.
Personal elevators are often used in construction and for various types of maintenance. Different types of aerial elevators are used by a wide variety of people, both trained and untrained, including owners, users, and those who rent the equipment.
Almost always available only to professionals, aerial elevators are becoming increasingly popular in the consumer market as well. Elevator operators have a reputation for wanting to get the job done at all costs, with little regard for safety issues. Due to a lack of training, operators and their supervisors are often unaware that they are doing something wrong.
The most common type of accident involving aerial elevators historically has been rollovers. Causes range from improper use of the equipment to lack of maintenance. In recent years, due to improvements in equipment and operator training (primarily osha/ansi compliance), the number of tip-over accidents that have characterized the industry since its inception has been declining. Nevertheless, elevator accidents remain a problem for the elevator industry and result in lawsuits and insurance claims. Proper preparation and knowledge of the problems associated with elevator accidents can significantly reduce the problems associated with these accidents.
Litigation scenarios and techniques used in defense - tipping. Tipping, which is the most common form of elevator accident, is usually caused by improper use of the machine, obstructions, non-use or misuse of outriggers, lack of knowledge of operator manuals and procedures, and lack of training.- Improper use of the machine. Ansi a92.6 clearly states that the machine shall not be operated on lifts in excess of the manufacturer's ratings. The manufacturer must meet different stability requirements for an elevator designed to operate on an inclined surface than for elevators designed to operate on a level surface (known as indoor or "slab" machines). To provide a safety margin, ansi requires that elevators, including slab machines, be tested for stability at an incline five degrees greater than the rated incline. Although manufacturers clearly label machines designed for use on level surfaces (e.G. "Use on level surfaces only"), sometimes operators, for reasons of economy or accessibility, use these machines outdoors, often resulting in tipping.
In one warehouse tipping incident, a covered elevator was being used outdoors to set up surveillance cameras. The elevator was not equipped with outriggers because without them it passed all the required stability tests when operating on a level surface. The operators drove the elevator onto a relatively level sidewalk and then onto a not-so-level flowerbed. Operating the elevator on a surface not specified by the manufacturer caused the elevator to tip over and injure the workers.
Standards clearly state that elevators must be operated on a surface not exceeding the manufacturer's specified limits. These limits should be clearly stated in the warnings on the machine. In addition to the warnings, some machines are equipped with tipping alarms. Pre-operation inspection of the machine and the environment should ensure that there are no surprises.
- Obstacles. Tipping of covered elevators designed to operate on level ground is usually caused by cutouts in concrete slabs for plumbing, wiring, and other building components. Some manufacturers use "safety devices" to protect against such accidents, but they are not effective in all cases. Standard a92.6 requires that scissor elevators pass a dive test, in which a machine with a specified load is driven at maximum speed into a depression 4 inches deep and must remain stable. In fact, there are deeper depressions, and in these cases, a mandatory workplace inspection indicates either operator neglect of the work area or one of several osha requirements for covering such obstacles.- Outrigger problems. Inability to use outriggers or lack of familiarity with their installation due to inadequate training is the cause of many tip-over accidents, especially on single-person elevators. In such cases, attention should be paid to whether the operator had access to and read the operating manual before the accident (e.G. In a weatherproof tube on the operator's platform).
Some manufacturers place easy-to-understand, language-independent illustrations of proper outrigger installation on warning labels on the operator's platform. The easier it is to communicate information, the more likely it is to be communicated. An example of inadequate use of outriggers is the use of single vertical elevators to set and adjust stage lighting. On a stage with scenery and props, there is little room for the elevator to be freely set up and maneuvered. Lighting and stage personnel are often more occupied with their art than with the mechanical operation of the hoist. Masters often use vertical elevators without outriggers, and sometimes one person rides the elevator without outriggers while another person pushes the elevator from lighting fixture to lighting fixture. Such actions are prohibited by ansi a92.3. A scenario involving such misuse resulted in the overturning of the hoist, killing the stage lighting supervisor. In this case, the rental company should have trained stage personnel in the proper use of the hoist when it was delivered. If the stage personnel found the use of the hoist unsatisfactory, they should have buy Asphalt pavers in California used alternative means of accessing the lighting fixtures, such as scaffolding or a boom elevator.
Interlocks. Interlocks, which are only required on certain types of machines, are often found in elevator accidents when they involve the use of outriggers. Problems associated with interlocks include reliability, a false sense of security in the user, and failure to identify alternative outrigger configurations (at the wall and freestanding). Outrigger interlocks are no substitute for a well-trained operator who uses common sense and follows proper operating procedures. Operator training issues
All elevator standards require the operator to read the operator's manual before operating the elevator. Without such familiarization, a hoist is a potentially dangerous tool. Casual users - those who need this information the most - often skip this step.
In one case in california, a young man who had no experience with aerial elevators, did not know about outriggers, and had not read the manual took a vertical elevator to install a "grand opening" sign at a restaurant. The young man set the elevator on a sloping sidewalk without outriggers, causing the elevator to tip over, resulting in injury. The young man then sued the manufacturer for making an unsafe product.
In court, his attorney questioned whether it was possible to install a machine with improperly installed outriggers. While it was physically possible, the young man could have installed and leveled the machine correctly if he had read the owner's manual. The attorney went on to inquire whether it was possible to misalign the machine without reading the manual. The answer was that if the operator had not read the manual, he was not authorized to use the machine. Thus, the court sided with the defendant manufacturer of the hoist.
In the event of an operator's inability to read or understand the language of the manual, ansi standards contain provisions allowing others to explain the manual. The issue of training is in a state of change. It used to be that an experienced operator (one who was reasonably familiar with or trained on the equipment in question) was more responsible for his or her actions than an inexperienced operator. Now, the recently adopted ansi a92.6 standard requires an employer to ensure that all employees operating self-propelled aerial work platforms are properly familiarized (trained, as well as read the operator's manual) before using them.
If the current ansi a92.6 standard applied to a hoist operated by a young person installing a restaurant sign, the restaurant owner would have to ensure that he or she was properly trained. In situations where the employer cannot provide training, the employer must find someone who can. Similarly, the lender of a machine is responsible for ensuring that the lender is properly familiarized with the machine. However, this responsibility cannot be placed on the manufacturer.
The date of the situation is critical in determining which training standards apply. An operator's efforts to familiarize himself or herself with the machine may be important in an earlier incident or irrelevant in a current incident where the responsibility for operator training rests with the employer. Accidentally making machines available for use can have serious consequences when dealing with training and familiarization issues.
Machine inspection and maintenance
Prelaunch inspections are generally required for all types of hoists. These may cover controls, safety devices, machine components, and warning signs and placards. After an accident, asking the operator about the pre-trip inspection can determine the operator's level of safety awareness.
In a case involving an allegedly defective scissor elevator step, the operator was asked if he had paid attention to the condition of the step before he allegedly slipped off it. The operator responded, "oh yeah, i've been up and down those steps hundreds of times." After a load-dropping accident, another operator stated that he could not read the control signs indicating the direction of the machine because they were obscured by paint. He had been up on this elevator several times before and the control inscriptions were "always like this." In both cases, the pre-lift inspection had apparently not been done or not done at all.
Standards state that aerial platforms that are not in proper operating condition must be immediately taken out of service until repaired. In practice, however, operators often use a machine in need of repair several times without incident, allegedly fearing that their employer will take action against them for refusing to use a defective machine. Osha regulations prohibit employers from forcing employees to use unsafe equipment. Proper repairs using equivalent replacement parts aerial elevator standards require that all repairs be performed by a qualified technician using equivalent replacement parts. Substitution of parts can lead to accidents. As an example, the replacement of a vertical elevator motor control relay is similar to the starter relay found on older model vehicles. Believing that all starter relays are the same, the maintenance department employees replaced the elevator's starter relay with a relay from an auto parts store. As a result, when the operator pressed the "up" button, the elevator would go up, but would not stop when the "up" button was released. As a result, the operator was pinned to the ceiling until the battery cables were disconnected.
Electrical injurywhen using elevators outdoors, there is the potential for contact with power wires. Similarly, the use of hoists by electricians can expose them to the risk of electrical shock. The ansi a92.2 standard defines a special type of hoist that must be used to service energized power lines. These machines have insulated boom sections and must pass rigorous tests for dielectric properties or current leakage.
All other elevators (e.G. All-terrain, large scissor, boom elevators in the construction industry) expose the operator to the risk of electrocution from contact with power lines. The operator compartment and operator's manual (ansi required reading) must contain specific warnings or signage. Ansi also requires operators to inspect the work area for potential hazards, including power lines.
Flash overflash overflash over is a highly specialized type of electrocution accident. It involves current flowing through hydraulic lines that have air pockets in them. In such cases, it is best to entrust the investigation from the outset to an engineering concern experienced in this field. These professionals, knowing what to look for, may uncover important clues that would otherwise be overlooked.
"...Accepts employers' use of the current edition of the national consensus standards in lieu of earlier versions incorporated by reference or adopted as such in osha standards. Such acceptance is based on the use of the current edition providing at least the same level of safety and health as required by osha standards."
Osha's compliance letters for scissor elevators state that it does not have specific standards, but rather ansi guidelines:"
"For more information on scissor elevator safety, please refer to the national standards ansi/sia a92.3, manually propelled elevating aerial platforms, and ansi/sia a92.6, self propelled elevating aerial platforms."
Osha addresses boom-supported elevating work platforms in the compliance letter, stating in part:
"
" .... 1910.67 applies to self-propelled boom-supported elevating work platforms. Boom-supported elevating work platforms are also covered by the american national standard ansi a92.5, boom-supported elevating work platforms. Employers are encouraged to comply with the current versions of the national consensus standards, provided that the current version provides at least the same level of safety and health protection as the applicable osha standards."
In a letter explaining which types of work platforms are subject to specific requirements, osha states that:
" . . If an employer fully complies with the requirements of the applicable ansi a92 series document, osha will consider this compliance to be an enforceable compliance with the applicable ansi a92 series document the following is a discussion of these standards in terms of their application to various parties and equipment.
Types of lifting equipment
Since there can be no one-size-fits-all standard, different standards apply to different types of equipment. Mechanical configuration, operating environment, and ownership conditions affect the specific standards for a given piece of equipment.
Ansi a92.2, titled "american national standard for vehicle-mounted lifting and turning devices," applies to articulating boom elevators that are typically mounted on trucks. These highly specialized machines, used primarily for power line maintenance and aerial tree trimming, are usually owned by the company that uses them. This ansi standard covers mechanical, structural, electrical, hydraulic, and structural requirements, and also contains extremely detailed electrical insulation and testing requirements that must be performed both in production and in the field to ensure safe operation in the hazardous environments in which these machines operate.
Ansi a92.3, titled "american national standard for manually operated lifting platforms," covers all lifting platforms that are not capable of moving under their own power the most common of these are single-passenger pushed vertical elevators, popularly called "genies," although a number of manufacturers produce them. Other aerial platforms covered by this standard include single or multi-passenger articulated boom elevators, non-powered scissor elevators and trailer elevators. The fact that the lifting mechanism is powered does not affect which standard applies to these elevators. Standard a92.3 emphasizes standards of manufacture, stability, inspection before use, training requirements, and actions by owners, operators, and lessors.
Ansi a92.5, entitled "american national standard for boom supported lift platforms," applies to self-propelled devices with a platform that can extend completely beyond its base. Standard a92.5 emphasizes the location, function, and interlocking of all necessary controls located on the platform. Since these machines are most often used outdoors or on slopes and rough terrain, this standard clearly defines the requirements for stability testing. And because these elevators are often rented, a92.5 also emphasizes the responsibilities of all parties involved - manufacturer, dealer, lessor, user, and operator - and clearly defines requirements for rental inspection, operator education, and training.
Ansi a92.5, entitled "american national standard for self-propelled lifted work platforms," covers most scissor elevators, as well as various other platforms raised by articulating arms. This standard emphasizes operator stability and control. It requires special tests to determine the slope (or lack thereof) at which the machine can be operated, as well as requirements for outrigger locks on machines that require outriggers for stability. Like the machines in standard a92.5, this type of elevator is often rented. This standard, like the a92.5 standard, emphasizes responsibility of all parties involved, inspection at rental, and operator education and training.
Persons involved in the operation of hoists
In addition to classifying types of hoists, ansi standards also classify the types of people or organizations involved in the operation of hoists.
A manufacturer builds and initially offers hoists for sale. The manufacturer may sell the elevators to an end user (such as a construction company or power company performing its own maintenance) or to a rental company, which in turn rents or leases the elevators to individual customers. Manufacturers' responsibility begins at the design level and includes the structural, mechanical, electrical and hydraulic aspects of the elevator, stability characteristics, required warnings and safety devices.
The dealer buys the elevator from the manufacturer or distributor and typically sells, leases and services the elevators. The dealer's responsibilities include providing manuals, training, pre-delivery training, record keeping, maintenance safety, delivery training, record keeping, modifications, compliance with manufacturer's safety bulletins, and assistance to owners and operators.
The owner owns the hoist by virtue of purchasing it. Owners are usually companies that specifically use these elevators or perform most of their services while on the elevator (e.G. Large contracting organizations, power line maintenance companies, or tree trimming services). Duties, more stringent than those of a dealer, include maintenance throughout ownership, inspection, training of operators and maintenance personnel, and compliance with manufacturer safety bulletins.
The user puts the hoist into service and often may be a business (such as a lighting contractor or sprinkler installer) that rents or leases the hoist for individual jobs. Users are required to keep and maintain operating and maintenance manuals (manuals must be kept on the machine, not in the office), inspect and maintain the machine, and train operators.
The operator directly operates the machine being used and is subject to the direct application of the standards discussed in the