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Ensuring Safe Use of Cranes
Have you ever looked up at a construction site and wondered just how safe those cranes are? If you have, you certainly are not alone. Since the highly publicized collapse of two tower cranes in New York, I have received numerous calls from safety managers, journalists, and others who happen to pass by, wanting to know what happened -- and, in some cases, why the collapse happened. At this point, anything that I say will be speculation, so I won’t go there. Instead, I will explain what should be done on the job to ensure this type of accident does not happen.
There is much more involved with crane work than just the crane and the operator. The Naval Facilities Engineering Command has what it calls the crane envelope. It includes the crane, load, operator, rigger/signalman, and the surrounding area. While we in the construction industry don’t use the term, we are required to pay close attention to these areas. You can be sure the collapses in New York, as well as accidents across the country, are the result of a breakdown in one or more of these areas. Before I continue, let me say that, considering the number of cranes in operation every day, crane accidents are not that common, especially tower crane accidents.
Regardless of the crane type, it must be assembled and inspected properly. Tower cranes are unique because they are under constant tension. When a crane is in an unloaded condition, the counterweight (that large hunk of concrete you see on the tail end of the crane) puts the load on the tower opposite the counterweight. When under load, the stress is on the opposite side of the tower. So what you get is a back-and-forth action that requires vigilance to ensure the structure remains sound and tower bolts remain at the proper torque.
Other areas of concern are to ensure the tower is properly supported. As the crane climbs, it must be braced to the structure every four stories, or 40 feet. If not, the structure will become unsafe. The load limiting system must be calibrated to ensure that it limits the crane’s capacity at all working locations of the hook. Tower cranes can have the capability to have various capacities, depending on jib length or counterweight size and/or location.
Load limiting systems should be set for the proper configuration and never exceeded. Moving parts such as hoist and trolley sheaves (pulleys), wire rope, brakes, hoist drums, and turntable bearings and bolts must be in good repair. These are the kinds of things the crane erectors should ensure. If the crane remains at the same site, it must receive frequent and periodic inspections by a competent person. These cranes are usually leased and move around the country, so inspection and correct assembly by highly qualified personnel are paramount.
Cranes today are becoming very complex machines requiring a highly skilled operator. I often wonder what some of the old operators I trained under would say if they could see all the new crane technology, such as load moment indicators and computers, that we use today.
Inspector qualifications are ambiguous, depending on where in the country the crane is operating. Some states, such as California, require a state accreditation to inspect cranes. Some require only that the employee ensure he is competent. A third-party inspector is recommended but not required in most states. Many construction companies, especially general contractors, mandate a third-party inspection to ensure objectivity and to reduce their liability. I am in the training business, so some companies send their inspectors to us or companies like ours for training and a certificate of competence. Presently, OSHA accredits crane inspectors only for the maritime industry.
Two categories of inspection must be done:
The frequent inspection is done from daily to monthly, depending on the severity of the work cycle. In the vast majority of cases, it is done monthly and is referred to by most as the monthly inspection. The frequent inspection is very general in nature and does not require any disassembly.
The periodic inspection is done from monthly to yearly, depending on the severity of the work cycle. It is done annually most of the time and is often called the annual inspection. This one requires a close look at all of the crane’s components and structure, including checking bolt torque. It should be carefully documented.
The Crane Operator
The crane operator should be well trained and experienced with the type of crane he is to operate. It may be a shock to some of you to learn that, in most states, the operator is not licensed or certified, and the contractor could put anyone in the cab. Thankfully, that doesn’t happen often.
There is a very good crane operator certification program taking hold in the United States. About 14 states now mandate this program, and several more are considering it. The program is the National Commission for Certification of Crane Operators (NCCCO), a nonprofit organization created by parties throughout the crane and rigging industry.
For years, ANSI/ASME B30.5 was the only standard for crane operators. It addressed the physical requirements, a written test, and a practical evaluation. Enforcement of this standard has been very lax -- to the point some in the construction business do not know what it is. With NCCCO, the written testing is administered by the International Assessment Institute. Practical testing is done with NCCCO-accredited examiners who must follow very strict criteria. Some insurance companies and general contractors are requiring employers to use NCCCO operators.
When I started my crane career, most cranes had an oiler. This was the entry position for crane operators. Along with being assigned the dirty work, such as wiping and greasing, the oiler received hands-on training and, if he was lucky, was taught the trade by his operator. He would get to operate the crane little by little until he was ready to be an operator. It could take up to four years to get a shot at the operator job.
Unfortunately, most mobile cranes today do not have an oiler, so there are relatively few new crane operators being properly trained, except for the Operating Engineers’ apprenticeship programs. This is the program I started under, and I think it is the best way to get into the trade. However, the Operating Engineers are not turning out sufficient numbers to eliminate the shortage we have today.
In order to provide the industry with properly trained operators, more training or apprentice programs will be necessary. We have begun a crane operator’s school that teaches the basics and provides actual seat time, but this program prepares someone for entry level only. Students leave with all of the requirements except one very critical ingredient: experience. Still works in progress, it will take some time before they are top operators. They will provide an alternative to trying to train people on the fly. (I know of companies that have put someone in the seat, showed him the controls, and turned him loose. Obviously, this is a tragedy in the making.)
The Signalman/Rigger and Load
One often-forgotten part of safe craning is the signalers and the riggers who attach the load. In the construction industry, rigging and signaling is often done by the trade to which the lift belongs. In locations such as shipyards, rigging is a trade in itself. Most complex or risky projects are reserved for trades such as ironworkers, boilermakers, or millwrights.
Loads must be properly balanced, and slings and rigging hardware must be used within their limits. For example, a dangerously low sling angle could cause the sling to break. The load to be hoisted must be safely attached to suit the operator because he is responsible after the load is hoisted. Dropped loads on a construction site can be extremely dangerous, not to mention costly.
There is a designated set of hand signals provided for controlling crane operations. To ensure safety, these signals should be followed to the letter—except when the operator does not agree, in which case he does nothing. He is not allowed to do something instead of the given signal. There is an established method of giving voice commands to the operator using radio or intercom systems. This is the usual method of signaling tower cranes.
In June, the NCCCO notified its examiners that a signalman certification program was ready to be released. We hope it will meet with the same approval as the operator certification program.
Established Policies and Procedures
Every job site should have established policy for crane operations detailing what authorizations are necessary for some types of lifts, such as using personnel platforms, work near electrical lines, critical lift designations, and procedures. With the development of new qualification and working standards, training, and self-policing by the construction industry, we can make accidents such as those in New York even rarer.