Why Tower Crane Accidents Keep Happening

The construction sites where fixed site lifting mechanisms and lifting structures are used, are hazardous production facilities. The year 2020 saw 35 recorded accidents in Russia. These resulted in 28 fatalities, attributed to the operation of lifting structures at monitored facilities. The majority of accidents related to lifting machinery between 2015 and 2020 were associated with the operation of tower cranes. For instance, out of 25 crane-related incidents, 12 (47%) occurred during the operation of tower cranes, 4 (20%) during the operation of crawler and mobile cranes, 2 (10%) during the use of manipulator cranes, and 2 (7%) during the use of overhead gantry, and while using the portal cranes. Despite the varied crane types, the focus on tower cranes intensifies when considering occupational accidents.

In addition to the human cost, crane accidents also lead to fiduciary losses as well. A study among Malaysian registered contractors revealed three key areas that increase the cost of a project when an accident occurs. These being project delays, medical expenses, and damage repairs to completed work and collateral damage. Although the study does not point out an exact number value for the increase in the costs, it demonstrates that out of the contractors who undertook the survey, 97.4% agree that project delays due to accidents increase the project cost, 94.8% agree that the additional cost of repairing completed construction or adjacent structures is significant. 89.4% of the surveys agree that the medical costs for compensating injured workers also increase the cost of the overall project. Moreover, human error accounts for approximately 70% of crane accidents.

A preliminary statistical analysis of accidents involving tower cranes, identified contributing factors. Furthermore, a Degree of Influence (DOI) was computed for each factor, providing a more nuanced understanding of their individual levels of significance. According to the findings of this study “Operator Proficiency” has the highest DOI. Whereas the seven factors that can be categorized into human-factor and safety management categories also have high DOIs associated to them.

An examination of human factor classification revealed key aspects that further refine the understanding of these incidents. These aspects include:

• inattention,
• failure in communication,
• operator error, and
• error of signal person.

Another study arrives at similar conclusions however they do point out that although human error-based accidents have a very high frequency, they rank low in severity of the accidents. They point out that the most prevalent failures in the dataset are:

• Inattention, a typical human factor that appeared in about 19% of incidents.
• The second most prevalent type (between 10 and 15%) contains three human factors, namely– improper rigging, – signalperson error, and– operator error.
• Environmental factors such as limited visibility and strong wind appear to reside within the least prevalent.

A point-cloud and display based safety feature was tested with five crane operators with work experiences ranging from 8 to 16 years. Although they point out that their solution was still in the preliminary stage and some of the issues would be sorted out in later iterations, the key insights obtained from their tests were:

• The operators generally agreed that the new safety solution was easy to use.
• The operators agreed that a real-time vision-based safety feature would help improve safety. However, the operators were also quick to point out that this does not eliminate the need for a signal person. The main reason was a general insecurity about solely relying on technology as it also put all the responsibility on the operators too.
• The operators could not form a consensus on whether such system necessarily improves efficiency. They pointed out that being able to view the scene in 3D helped them choose an optimum path faster. However, in situations where direct line of sight application was still feasible the system acted as a hindrance. These cases demonstrate that technological assistance plays a significant role in enhancing the overall safety of workers on a construction site, particularly in the context of crane-related accidents