The Center for Construction Research and Training (CPWR) studied data from a 14-year period and concluded that the leading causes of crane-related fatalities were: Overhead Power Line Electrocutions: Across the 14 years CPWR studied, more than 100 construction workers were electrocuted after making contact with overhead power lines. In about half of these incidents, it was the boom or a crane cable that came in contact with the power line. Crane Collapses & Crane Boom Failure: More than 20% of the fatalities CPWR looked at involved crane collapses. Most of these fatalities occurred because the crane was overloaded, or was operating on an unstable surface such as icy or uneven ground. A small number occurred due to shifting of the load. The Crane Boom or Jib Striking a Worker: A handful of workers each year were killed when they were struck with the boom or jib of the crane. Nearly half of these accidents occurred while workers were dismantling the boom. Other fatalities occurred when workers were lengthening the boom, or when a worker was struck by a swinging boom.