Dr. N. Subramanian, Ph.D., FNAE, an award-winning author, consultant, and mentor, Maryland, USA
There is a diverse array of cranes for use in the infra construction industry, ranging from compact jib cranes employed within workshops to towering tower cranes integral to erecting tall structures. To ensure their safety, stringent measures are implemented, including limiting the load lifted to a value below the crane's capacity, thereby establishing a crucial safety margin.
To prevent mishaps, rigorous adherence to safety protocols, routine crane inspections, thorough site and soil assessments before crane installation, and employing only qualified and experienced operators are necessary considerations. Additionally, steering clear of power lines and refraining from operations during adverse weather conditions are imperative. By meticulously following these guidelines, the incidence of crane accidents can be significantly reduced and a safe work environment maintained.
Global Incidents of Construction Crane Failures
Thane, India: On August 1, 2023, as many as 17 people died and three injured as a girder launcher gantry fell on them during construction of the third phase of Samruddhi Expressway in the Thane district of Maharashtra. The Samruddhi Mahamarg is a 701-km-long expressway connecting Mumbai and Nagpur. The work for the 2.29-km viaduct was given to Navyuga Engineering Company Ltd, which contracted VSL India Ltd, a Singapore-headquartered company, to launch the viaduct using specialized launchers.
The girder launcher gantry is a special-purpose mobile crane used in bridge construction. It is used to install precast box girders in highway and high-speed rail bridge construction projects. The automatic launcher weighing approximately 700 metric tons had completed 98 out of 114 spans on this stretch. The mishap took place around 11.30 pm when a team of 28 people of VSL India Ltd were doing preparatory work for the next day, when the launching gantry crane, which lifts and fits the concrete girder at a height of 35 meters, came crashing down from Piers 15 and 16 of one carriageway.
Ranipet, India: On Jan 22, 2023, four people were killed and at least six injured after a crane crashed during a festival at Draupathi temple in Ranipet district, 85 kilometers west of Chennai, the capital city of Tamil Nadu. Reports said around eight people were on the crane to receive garlands from the devotees when the accident took place. A part of the crane was on higher ground. This soil imbalance appears to have caused the crane to topple.
Visakhapatnam, India: On Aug 1, 2020 in Visakhapatnam, Hindustan Shipyard Limited (HSL), a Government of India undertaking shipyard, a crane accident happened when the workers were carrying out an inspection of the crane used to carry equipment for shipbuilding. The massive crane suddenly crumbled and crashed to the ground, killing 11 people.
Miami, USA: In June 2021, a residential building partially collapsed, leading to the failure of a construction crane. Investigations revealed structural flaws in the building, and the crane's collapse resulted in significant damage to the surrounding area. This incident underscored the need for rigorous structural assessments and adherence to safety standards.
Sydney, Australia: In early 2022, Sydney witnessed a construction crane failure during the development of a high-rise building. The incident raised concerns about the maintenance and inspection protocols for cranes, prompting a re-evaluation of safety measures within the construction industry in the region.
Dubai, UAE: Dubai experienced a crane collapse incident in 2020, leading to disruptions in construction activities. The investigation pointed towards a combination of factors, including adverse weather conditions and potential mechanical issues. This incidence emphasized the significance of considering environmental factors and ensuring proper equipment maintenance.
London, UK: A construction crane failure occurred in London in 2019, causing the closure of surrounding streets for safety reasons. The incident drew attention to the importance of thorough risk assessments and safety precautions, particularly in densely populated urban areas.
Shanghai, China: Shanghai witnessed a crane collapse at a construction site in 2023, raising concerns about the quality of crane components and construction practices. The incident prompted authorities to review and strengthen regulations related to crane safety and construction standards.
Kelowna, Canada: On July 21, 2021, four construction workers on the ground and the crane operator were killed in an accident at Kelowna, 390 km east of Vancouver, Canada. The upper portion of the crane smashed into a neighboring building. The reason for the crane’s fall was not determined.
Florida, USA: On February 6, 2020, a crane collapsed in the Pinellas County, Florida, during a severe storm, resulting in the closing of I-275 overnight. The crane was used to install a traffic signal when it was struck by a gust of wind and toppled over.
California, USA: On February 28, 2020, two cranes collapsed after colliding at SoFi Stadium in Inglewood, California. The cranes were being used to install a roof when they collided, causing one of them to topple over.
Rostock, Germany: On May 2, 2020, a crane collapsed during an overload test at the Liebherr yard in Rostock, Germany. The crane was being tested to its maximum capacity when it collapsed, injuring two people.
Toronto, Canada: On August 6, 2020, a crane came toppling down in Regent Park—Toronto, where a civilian barely escaped by running out from under the falling front of the jib.
Texas, USA: On September 16, 2020, two cranes got entangled on a jobsite located in Austin, Texas, injuring 22 people.
These examples underscore the necessity for comprehensive safety measures, stringent regulatory oversight, and industry-wide awareness to prevent construction crane failures and safeguard both workers and the public from potential hazards.
Causes of Crane FailureCrane accidents are relatively frequent and can be caused by a variety of factors, including operator error, wind gusts, overloading, and structural defects. They can have devastating consequences, resulting in injuries and fatalities. United States’ Occupational Safety and Health Administration (OSHA) has estimated that 93 percent of all crane accidents are due to human errors (Ref.5). Some of the causes are briefly discussed below:
Operator error: Crane operators are responsible for the safe operation of the crane, and even a small mistake can have catastrophic consequences. Some common operator errors include overloading the crane, failing to properly secure the load, and operating the crane in unsafe conditions.
Mechanical failure: Cranes are complex machines, and like any machine, they can fail. Mechanical failures can be caused by a variety of factors, including wear and tear, improper maintenance, and manufacturing defects.
Weather conditions: Cranes can be affected by wind, rain, and other weather conditions. Strong winds can cause a crane to topple over, while heavy rain can make the ground unstable.
Improper setup: Cranes must be properly set up before they can be operated safely. If the crane is not set up properly, it can become unstable and may tip over.
Rigging failure: The load being lifted by the crane must be properly rigged. If the rigging fails, the load can fall, causing serious injuries or fatalities.
In addition to these causes, crane accidents can also be caused by poor communication, inadequate training, and rushed work. According to OSHA (Ref.5), nearly 45 percent of crane-related accidents are caused by contact with power sources such as power-carrying lines. The second most common cause is falling of cranes either by overturning or due to the eccentricity of load being lifted, while 10 percent of crane accidents is due to poor communications.
Preventing Crane AccidentsPreventive measures include following safety procedures, inspecting cranes regularly, inspecting the site and the soil before installing the crane, and employing qualified/experienced operators. It is also important to avoid power lines and working during inclement weather.
Here are some additional tips for preventing crane accidents:
Professionals should check the route before use: All obstacles must be noted and proper minimum clearance must be maintained from any power lines or sources. Dedicated observers during both crane movement and crane operation should make sure that proper clearance is maintained. If possible, power lines along the route should be de-energized. The same concerns apply to any power lines or sources near the work area also.
Plan ahead: Before using a crane, sufficient time has to be taken to plan the work carefully. This will help to identify potential hazards and take steps to mitigate them.
Use the right equipment: It should be made sure that the right crane is used for the job. The crane should be able to safely lift the load it is intended to lift at the location, and it should be properly rated for the wind conditions.
Monitor weather conditions: Weather conditions should be monitored constantly for unexpected changes. Crane operations should be stopped immediately if any inclement weather is expected or noticed anywhere in the vicinity.
Inspect the crane: Before the crane is used, it should be inspected carefully for any signs of damage or wear. If any problems are noticed, it is better to avoid using the crane until it has been repaired.
Use qualified operators: Only qualified crane operators should operate the cranes. These operators will have the necessary training and experience to operate the crane safely.
Follow safety procedures: Safety procedures should always be followed when operating a crane. This includes using the proper rigging, keeping the area clear of people, and being aware of the wind conditions. All team members should follow proper procedures at all times of operation and during crane assembly or disassembly.
Do not exceed the maximum load capacity: The maximum load carrying capacity of the crane should never be exceeded. Proper load placement is vital. Proper centering of all loads and securing the loads in the slings is important. If necessary, taglines should be used to control swing and rotation of the load.
Check ground conditions at project site: Ground conditions at the site must be checked for saturated soil or freezing or thawing of ground. Skidding must be used, if required, to spread out ground loads for extension of outriggers.
Anti-collision system: When a tower crane is used close to buildings, roads, power lines, or other tower cranes, an anti-collision system should be used. This operator support system reduces the risk of dangerous interactions occurring between a tower crane and another structure. In countries like France, tower crane anti-collision systems are mandatory.
(Some more guidelines and checklists for safe crane operations are given in Ref.5).
- ASME B30.5-2021 Mobile and Locomotive Cranes, American Society of Mechanical Engineers, 72 pp