By Dave Remter, Account Manager, and Mark Steinhofer, Ph. D., CHST, Account Manager
Safety Management Group
It happened again in September. A 25-year-old man working for a wireless tower installation company climbed behind the controls of a small crane in Indianapolis. His task was to move a 5,000-pound generator. Co-workers reported that the man felt the crane had the capacity to lift the load without any problems, so he didn’t choose to take the couple extra minutes to set the outriggers.
As the generator came up, the operator realized that the crane had become unstable. He quickly moved to lower the load back to the ground, but the crane began to tip. The man raced away from the controls, but didn’t get far enough before the crane and load tipped over, crushing and killing him instantly.
The scenario is all too familiar to safety professionals, as cranes are some of the most misunderstood workhorses on job sites. Nearly everyone who works in construction is fascinated with cranes and their ability to lift and move massive loads with pinpoint accuracy. But all too often, workers fail to treat cranes with the respect they require.
When we think about crane accidents, we tend to remember the dramatic incidents that happened with huge cranes. However, those giant pieces of equipment are usually operated by professionals who are well aware of the hazards. The accident described earlier happened with one of those smaller, truck-mounted cranes that are used by a wide variety of contractors in an even wider array of settings. And while you may think that a 5,000-pound load is less dangerous than a 50,000-pound load, rest assured that it can kill you just as quickly and effectively.
Crane accidents tend to be very costly in equipment losses, damage to property, and injuries to workers. The direct costs related to damage, injuries, and OSHA fines tend to be very small when compared to the indirect costs of lawsuits from victims’ families and owners of damaged property. And, most of the time, those accidents are the result of not fully understanding how cranes work, ignoring the physics involved with their operation, or simply failing to follow basic steps to safeguard workers.
Years ago, safety rules governing crane operations were scattered here and there. But in November 2010, OSHA issued a new standard that collected safety standards into a single document. Along with that new standard is a certification process that will be fully implemented in 2017. It calls for crane operators and those working around cranes (such as the people making signals) to pass a written test and practical test of their skills.
While you don’t need to be a mechanical engineer to operate cranes safely, the following basic steps will help to ensure that you don’t encounter any safety issues.
1. Have a certified operator. Even though operator certification will not be required for a couple years, safety-conscious contractors and owners would be wise to use identical standards on their jobsites immediately. After all, a crane in the hands of an unqualified operator can be a deadly weapon. Riggers should also be properly trained on setting the crane up for the specific load and circumstances.
2. Inspect, inspect and inspect. Verifying that the crane has received its annual inspection is only the beginning. It’s important to check the operating functions daily to ensure that everything is working properly and that there are no defects or cracks in the support members. The cranes of a generation ago were made with alloys that could handle overloading and other abuse. Today’s cranes use materials that are less tolerant of mishandling. Longtime operators are often surprised to discover that the tricks they used to push cranes beyond the limits in the past can easily create very dangerous situations with newer cranes.
Overhead cranes used in heavy industrial applications such as steel making need to be inspected just as carefully. Many of these cranes spend decades working in extreme environments such as melt shops. That constant exposure to intense heat and temperature swings can cause the beam and other structural members to become brittle and lose strength or even fail.
3. Know what’s below. The most powerful, carefully rigged crane is only as strong and stable as the surface upon which it stands. You need to know the classification for the soil or other material under the crane, and adjust your setup and load limits accordingly. While many cranes are equipped with outriggers, extending them doesn’t necessarily mean that you’ve provided a stable surface. Outriggers displace the weight on the lift much the way that snowshoes spread your weight out so you don’t sink into the snow. The pad and float at the end of the outrigger carry a great deal of compression force when the crane is under load. Too much force can cause them to punch through the ground, causing the entire crane to tip.
It’s important to know the load weight and how that is affected by the conditions of your job site. The crane’s load chart can help you determine whether your lift will be safe. The allowable load will depend on whether the tires or outriggers are being used, along with other factors. For example, asphalt may seem to be a stable surface, but on a warm day, it may become very flexible. Even concrete may not provide enough strength if there is a void beneath it.
We remember a situation when a mobile crane was placed on the top floor of a parking garage. The floor was strong enough to handle the crane’s weight when it sat on its tires, but once the outriggers were deployed and the lift began, the compression force flowing through one outrigger caused it to break through the floor. The crane tilted, and as the floor weakened under the additional compression, it fell through to the next floor, causing extensive (and expensive) damage.
One way to increase the safety of a crane is to place cribbing under the outriggers. However, you have to ensure that the cribbing is capable of handling the load given the materials and conditions underneath it without failing or cracking. Simply placing a sheet or two of plywood under each float usually won’t be enough.
4. Plan for swing. The counterweight and boom travel within a specific arc that’s called the swing radius. It’s important to ensure that the area within that radius is barricaded off, and to establish a control zone for those authorized to work in the immediate area. Also check the area every day to ensure that there are no objects the boom might strike, such as power lines. If such obstacles exist, be sure that the operator and other workers are aware of the plan for avoiding them.
5. Use cranes properly. Cranes are engineered for vertical lifting. That doesn’t stop some crews from trying to use them for side loading or other improper activities. Using a crane to drag something across the ground or from under an obstacle puts extreme stress on the boom, the turntable, and all the structural members. It could potentially weaken key components and lead to their failure. If someone on the site has used a crane improperly, be sure to inspect it thoroughly to ensure that its integrity has not been impaired.
6. Stay in touch. Whether you use radios, air horns, or hand signals, there needs to be clear communication between the operator and the other workers. That’s especially critical when a crane is making a lift in which the operator cannot see the load, such as when air handling equipment is being delivered through an opening on another side of a structure. Don’t assume that everyone knows how instructions will be communicated. Follow OSHA’s specific guidelines, and make sure that everyone on the site knows exactly what each signal means.
7. Pay attention. We’ve seen plenty of sites on which operators are talking on cell phones while moving the crane, napping between lifts, or distracted in other ways that have the potential to create dangers for their fellow workers. Everyone associated with a crane needs to stay alert and focused on the job at hand – especially on critical or difficult lifts.
8. Avoid man-baskets. Sometimes it looks like the easiest way to put employees where they’re needed is to lift a man-basket to the work area. However, that approach creates hazards that must be tested and addressed before work begins, such as providing proper fall protection, verifying basket capacity, and checking that the basket is properly attached. In addition, the safety of the employees in the basket is entirely dependent on the skill of the operator, and a simple mistake could have tragic consequences. Before using a man-basket, consider whether an articulating boom lift or a scissor lift might provide a safer alternative.
9. Don’t use cranes for storage. In areas where site security is a concern, it’s not unusual to see laborers end the workday by attaching a compressor or similar piece of equipment to the crane and suspending it for safekeeping. It’s a common practice, but one that’s very risky. In addition to the danger that someone could walk beneath it, a strong wind could cause the load to sway – perhaps to the point of toppling the crane. But an even better reason not to do this is that most of today’s newer cranes are hydraulically-operated. A small leak anywhere in the system will eventually reduce the hydraulic pressure to the point where the boom will drop, and the suspended load will fall on whatever is below it – maybe a more expensive piece of equipment.
10. Start with a plan. Each lift is different from another, and it’s important to review load weight capacities, the integrity of the equipment, the possible effect of wind, and other factors. The operator, riggers, and other workers involved with the lift should be part of that planning process.
After all, the standards requiring tag lines on loads, capacity limits, ground stability, and similar factors have all been adopted because incidents, injuries and fatalities demonstrated a need for them. Following those rules and ensuring that your operators and other workers have the right education, training, and experience will protect everyone involved.
