Ensuring Safe Use of Cranes
New qualification and working standards, training, and self-policing by the construction industry can make accidents such as those in New York even rarer.
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.
The Crane
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.
The Inspection
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.