Missing screw and nut assemblies caused a construction hoist accident that killed five people

Missing screw and nut connections were the cause of the collapse of a construction elevator in Sweden, in which five construction workers died last year.

The accident at a construction site in Ursvik, Sundbyberg Municipality, Sweden, occurred on December 11, 2023 during the construction of a 14-storey apartment block.

A rental company provided the general contractor Andersson Company with the Scando 650 FC hoist for the work, according to the Swedish Accident Investigation Authority. The authority has now published a report into the incident.

On August 24, the elevator was installed and inspected by an accredited inspector. During the construction work, the elevator mast was extended.

On December 5, the last extension before the accident was carried out so that the elevator could reach the ninth floor.

But on December 11, between 9:41 and 9:42 a.m., the elevator car with five workers on board fell from the 9th floor. All five were killed.

An investigation by the Swedish Accident Investigation Board found that five of the bolt and nut assemblies needed to hold the mast sections together were missing.

Between two of the sections, all four bolt and nut assemblies were missing and the mast was held together only by the friction in the joints between the mast tubes and the support of a secondary structure.

The investigation report states: “The accident occurred when the load on the mast, which was missing the four bolt and nut assemblies, became greater than the structure could bear, causing the mast sections to separate and the elevator car to fall to the ground.

“The screw and nut sets were probably already missing when the mast was extended on November 1st. However, this was not discovered either during assembly or during the inspections and service measures carried out after assembly.”

The report concluded that the accident was caused by “failure to carry out relevant safety checks on the lifting equipment”, which resulted in the missing bolt and nut assemblies not being detected.

It continues: “At system level, the reason was that the current requirements for safety measures related to the installation of construction hoists were not sufficient to ensure adequate safety for users.”

recommendations

The report made a number of recommendations to various bodies. The Work Environment Authority, Sweden’s regulatory body that enforces laws on working environment and working hours, was recommended to:

• Investigate how safety measures can be improved in the assembly process of construction hoists.
• As part of your oversight of the systematic work environment management system, examine how the risks associated with construction hoists are managed.

His recommendation to Andersson Company Byggnads AB was:

• Integrate risks associated with the installation of construction hoists into your systematic occupational safety management.

And the recommendation to the construction hoist and lifting equipment supplier ABC Bygghissar och Byggmaskiner AB was:

• Improve inspection and maintenance routines to reduce the risk of assembly errors.
• Take steps to ensure that established safety routines are followed and deviations are reported and corrected.