Ways to ensure tower and mobile crane safety
Cranes are workhorses on large-scale construction projects, providing the efficient and effective movement of heavy construction materials throughout the site. While safety is the number-one priority for crane operators, accidents and near misses do unfortunately happen, and often with serious consequences. Human error continues to be a major cause of crane accidents— with estimates as high as 90% 1 —therefore, they can be considered preventable.
The best way to mitigate accidents is a strong commitment to safety across all aspects of a construction project. The following are important safety tips and best practices to help ensure the safe operation of tower and mobile cranes and keep construction projects running smoothly.
Tower cranes are fixed and commonly used in high-rise building construction. They are designed, tested, and manufactured to lift and move heavy loads safely. When used properly, they are safe, reliable, and can lift heavy loads to great heights.
It’s critical for a construction project to operate their tower crane safely by observing safe operating practices including its initial installation. In Canada, the code for tower cranes is CSA Z248-172 . Construction project managers and operators should familiarize themselves with the code, as well as applicable codes in their province and jurisdiction, and it’s recommended they adopt the more stringent requirements.
It’s also important that project managers adhere to the tower crane manufacturer’s specifications and requirements, along with the oversight and signoff from a professional engineer where applicable.
The safe operations of tower cranes include (but are not limited to) the following practices:
- Ensure operators are knowledgeable of the crane’s construction and relevant safety codes and standards, including maintenance needs for the equipment.
- Complete inspection, testing, and maintenance as required – daily, weekly, and annually – in accordance with the manufacturer’s recommendations and the requirements of the jurisdiction.
- Provide the load rating chart with each tower crane and attach it in a location visible to the operator while seated at the controls and at remote control stations. The operator should be familiar with load limitations.
- Consider weather conditions, including temperature (greater than -20 oC,) wind (less than 50 km/h,) electrical storms, snow and ice, and visibility.
- Isolate and de-energize overhead power lines when possible. If not possible, a minimum clearance of three metres should be maintained between the crane, or the load being handled, and the energized power lines. It’s recommended that the stricter jurisdictional authority be observed.
- Follow load management guidelines closely. It’s important that loads to be lifted weigh within the rated capacity of the crane and are properly rigged by a competent person to prevent any dislodgement. Prior to unhooking, the load should have safely landed and blocked. Whenever possible, don’t leave loads suspended and arrange to prevent them from passing over workers.
- Assign a designated qualified signaller to work with the crane operator when signals are required to control hoisting operations. Except for a ‘stop’ signal, the tower crane operator should only take direction from the designated signaller.
Mobile cranes can be mounted on a crawler, or a truck type carrier that is primarily hydraulically powered with a telescoping boom. The main benefit of a mobile crane as opposed to a tower crane is exactly that: it’s mobile. It can be moved around the job site itself, or to other job sites easily. However, there are significant lifting height limitations to the mobile crane as it’s limited to how far the boom can be extended.
The safe operations of a mobile crane are similar to a tower crane, but there are some significant differences. Safe operating practices of mobile cranes include, but are not limited to, the following:
- Avoid or remove obstructions to allow the movement of the load. As mentioned above, avoid passing loads over workers, pedestrians, and roadways. Obstructions such as energized power lines are a major cause of mobile crane accidents — nearly 45% of the cases according to the Occupational Safety and Health Administration4.
- Ensure ground conditions have enough stability and bearing capacity to support all loads placed on it by the crane. Special considerations need to be made when a mobile crane is located beside buildings under construction with possible uncompacted backfill, along trenches, or areas where water mains, sewer pipes, etc., are buried.
- Be mindful that leveling can significantly affect the load rating capacity. The load rating charts are based on the crane being perfectly level in all directions. A crane that is three degrees out of level may need to reduce the rated capacity by as much as 50%5 .
While job sites will always have hazards, it’s vital to keep the potential dangers of crane operations at bay. By following relevant safety codes and industry best practices, construction project managers and operators will be doing their part to ensure employee safety, peace of mind, and a successful construction project.
1 Crane Safety – Stats and Facts. SafetyNow ILT. (n.d.).
2 CSA Z248-17. (2017, December 1). CSA Z248-17 - Techstreet
3 Mobile Crane Safety: Factors Affecting Rated Capacity. (2018, November 15). JE Spear Consulting, LP | Environmental Consulting Services. h
4, 5 Crane Accidents. Graphic Products. (n.d.).