Anyone who has walked downtown in a large city and looked up has seen them - large cranes. Tower cranes are fixed to the ground on a concrete slab (and sometimes attached to the sides of structures as well). Tower cranes often give the best combination of height and lifting capacity and are used in the construction of tall buildings. The base is then attached to the mast which gives the crane its height.
Tower cranes dotting a skyline are a proud reflection of a growing city. We all interpret multiple cranes in a downtown area as signs of vibrancy and growth. However, any construction zone can be the site of accidents. Tower cranes are no different. Accidents involving cranes are rare, but the collapse of a crane in downtown Seattle on April 27, 2019, is a reminder of the dangers that can occur. While the cause has yet to be determined, the horrendous accident serves as a reminder of the three main dangers associated with overhead cranes on construction sites.
Electrical Hazards
According to OSHA, the federal agency that sets and enforces occupational health and safety rules, cranes coming into contact with high-voltage power lines represent nearly 50 percent of all crane accidents. When a metal part of a crane comes into contact with energized power lines, the person who is touching the crane at the time is electrocuted, and others in the immediate vicinity (usually those guiding the load) may also be injured or killed. OSHA guidelines outline the safe distance operators must maintain outside the 10-foot danger zone of power lines.
Overloading
Another frequent hazard involves overloading. According to OSHA, 80% of all crane upsets and structural failures can be attributed to exceeding the crane’s operational capacity. Inadequate training is usually the culprit when operators inadvertently exceed the crane’s lifting capacity. Operators must know the weight of a load and the capacity of the crane.
The use of load-measuring technologies can minimize overloading and operator incompetency. Also, OSHA requires formal crane operator training, and certification is required for those using equipment with a maximum rated capacity greater than 2,000 pounds.
Falling Materials
The third main danger associated with tower cranes involves falling materials, which are often caused by visual impairment, two-blocking, slipping, mechanical failure, or operator incompetence. Improperly secured loads can slip and may land on workers or pedestrians. Undesired movement of material can pinch or crush workers involved in the rigging process. Slings and attachments must be adequately secured to prevent slippage.
Also, proper head, foot, hand, and eye protection must always be worn around tower cranes. When moving items, an operator should never raise the load higher than the required clearance. OSHA has requirements for operator certification and regulations regarding their use based on wind speed.
Cleveland Construction makes safety on the jobsite our top priority. And, we strictly adhere to all OSHA standards for tower crane operation among all our employees and subcontractors. Cranes are a fact of construction life; accidents need not be.