Cranes are becoming commonplace on tree care work sites, particularly given the wide variety of shapes, sizes and configurations that are available. While a crane can make tree work safer and more efficient, these valuable tools do require some thought, knowledge and training to use safely and correctly.
Cranes have uses on the work site beyond the typical tree removal or large pruning operations and can be extremely helpful in getting woody debris to the chipper or truck, or even providing a secure tie-in point when the tree to be removed is not an option. No matter how the crane is being used, crews need to remember that it is a large, heavy—not to mention expensive—piece of equipment with specific strengths and weaknesses.
Improper use of a crane can, and often will, result in catastrophic accidents magnified by the height and weight of the machine.
Tree care industry organizations, training companies and others offer a variety of demonstrations and seminars on crane use. Probably the best place to start is the section on crane use in tree care in the Z133.1 (American National Standard for Arboricultural Operations: Safety Requirements). Another topic that tree companies must be aware of is the possibility of differing standards in their particular location, as state, provincial and municipal governments may all have rules and regulations regarding crane use and operation.
There is obviously nothing better than hands-on experience and training with any new piece of gear, but some basic principles, knowledge and understanding of cranes and how they can be used in tree work are an excellent place to start before firing up that big diesel.
The first person to see the job, typically whoever’s doing the estimating, should already be thinking about how the crane will be set up, if the job will require one. Every possible factor that is going to affect the crane and its operation should be considered and integrated into the setup plan.
Possible subjects should include, but not be limited to size of the needed crane; traffic control; overhead lines; septic tanks or other underground hazards; quality of the ground (soft, firm, level, etc.); quantity of blocking, cribbing, pads needed; and even whether a second crane might be required. All of these items, and possibly more, should be identified and prepared for before the crew receives the work order, as nothing can cause a job to go “south” more quickly than poor preparation.
Cranes are meant to be used in a level position on a surface that will support their weight and the weight of the lifts. Some work sites are going to require a lot of preparation to create this level position and firm surface, but not doing so can easily result in tragic and costly consequences. One part of the set-up planning that often gets neglected is the location of trucks and chippers in relation to the crane.
Placing these pieces of equipment correctly can often make the job much more efficient and allow the crew to take full advantage of the crane to move woody debris from treetop to truck bed.
Although sling selection might seem like a fairly minor part of crane work, it’s actually a topic that can greatly affect safety and efficiency and impact the energy expended by the climber.
Traditional slings in crane work have typically been of the wire loop or choker type familiar to loggers everywhere. However, many of the more recently developed “exotic” fibers, such as Samson AmSteel and others, are not only perfectly suited for sling use with cranes, but in some cases stronger than the steel they replace. The additional advantages of lower weight and easier use make fiber slings a much better choice for crane/tree interactions.
The use of fiber configurations in slings also allows the possibility of balancing systems where the whole top of a tree is attached to the hook of the crane by multiple points all equally loaded, thereby helping assure a smooth, even lift when the cut is completed.
How well or how poorly the crane is operated can often be the difference between a safe, efficient tree job and one that will give the company owner night sweats.
- A tree company that owns or is interested in purchasing its own crane should be aware that some states and/or municipalities require licensing for crane operation; and given the amount of money typically spent on a crane, “on-the-job” training for the chosen operator may not be the best choice for long-term crane, crew and company financial survival.
- Crane operator training courses, though not always tree industry specific, are readily available in most states/ provinces.
- Should a tree care company prefer to rent a crane for individual jobs, they should request an operator from the company who is familiar with crane tree work, as it can be very different from construction crane use.
- Repeat business with a particular crane rental company can help both the tree and crane company know what they can expect from one another and grow more efficient in their tree crane operations.
If a crane is being used as a tie-in point (TIP), the climber must do a variety of things to assure safety and security. A crane can only be used to lift a climber into a tree or as a TIP when the person responsible for the work has decided that this is the most practical and safest method available. Whatever is being used as a TIP must be secured through a locking shackle or similar method to avoid possible failures in the system; should be a designated anchor point; and must not interfere with the crane’s operation or warning systems. A work positioning lanyard through the hook of the crane is not an acceptable or appropriate means of primary support for a climber.
Once the crane is under load, the climber should be detached from the crane and secured by another TIP such as the tree, another tree or even another crane. If none of these are possible, or if to do so would be unsafe, the climber can remain attached to the crane under load, but the crane operator cannot exceed 50 percent of load capacity for the given extension and boom angle.
This can be one of the most challenging topics involved with crane use in tree care. After all, tree work sites are typically pretty noisy already without the addition of even greater distances between the climber, crew and crane operator, plus the noise of the crane’s engine. Add in the large loads that are dancing through the air and the need for everyone to understand exactly what is going on and is expected of them, and clear, concise communication becomes extremely important.
The appendix of the Z133.1 illustrates a number of simple hand/arm signals that can be useful in crane operations. A number of electronic methods, such as radios, throat mikes and hard hat systems, are also available.
No matter which method the crew chooses to use, the key to smooth communication and operation is everyone understanding all the signals and operation before the crane even fires up.
In some situations, the crane operator and the climber will not be able to be in visual contact, which will require the use of a spotter. The spotter must relay the signals in a timely fashion, and keep the folks at both ends of the “stick” aware of what is going on.
All of this should be known and understood before work begins, as figuring it all out “on the fly” is a recipe for disaster.
Cranes are big, strong, heavy pieces of equipment, meant to deal with a lot of weight. Just like many other pieces of gear, they’re intended to deal with that weight and those forces in a specific way; hit a crane with that weight the wrong way and it’ll crumple like a chalupa wrapper.
A crane is designed and built for a static lift, meaning it is meant to lift a given amount of weight smoothly up. They are not intended or designed for dynamic loads, meaning they are not meant to have loads “dropped” into their load line or hook.
There are a large number of aerial chain saw cutting techniques that can help minimize the occurrence of dynamic loading, but hook and sling placement are going to be the most critical. Typically, the climber and operator want to work to have the tip of the boom, load line and hook forming a straight line down to the center of mass of the load. This configuration will do a great deal to eliminate swings, drops or other dynamic loads upon the crane.
As stated previously, using cranes in tree care is a big subject, one that contains much more information than covered here, but these concepts, along with some further research and hands-on training, can help tree care workers better and more safely use a crane, a piece of equipment that can make many a tree job a wonder of safety and efficiency.
Editor’s Note: This article was originally published in the January 2012 issue of Tree Services.