Machine & Operator Safety
Concrete manufacturer fined $175K after worker death, injuries to others
January 23, 2020 by Manufacturing AUTOMATION
A manufacturer of pre-stressed and pre-cast concrete products located in Windsor, Ontario has been fined $175,000 in provincial court after one worker was killed and another seriously injured during a bridge construction project.
Following a guilty plea and the fine, Prestressed Systems Inc. (PSI Inc.) also received a 25-per-cent victim fine surcharge credited to a special provincial government fund to assist victims of crime.
A Ministry of Labour, Training and Skills Development investigation found that on the date of the incident, April 12, 2018, workers were working on the concrete form for a large pre-stressed bridge girder that PSI had been hired to manufacture for the Nagagami River Bridge project.
The process of pre-stressing concrete is a means of increasing the strength of a concrete structure, using tensioned steel cable strands embedded inside the concrete.
Strands of cable are passed through a concrete form and secured to anchor plates and anchor grips. After the concrete cures around the stressed cables, the exposed ends of the cables are de-tensioned and cut.
To take the tension off the cables, hydraulically powered cylinders are used, and support sleeves are manually removed by workers.
During this process, the cable strands act like big elastic bands; when the cable strands are stretched and held, they hold a large amount of stored energy, and proper de-tensioning equipment and procedures are needed to safely remove the tension from the cable strands.
Four workers were removing the support sleeves from the cylinders when anchor plates – to which the still-stressed cable strands were attached – suddenly failed and struck two of the workers. One of the workers died, another sustained multiple injuries and two others survived without significant physical injury.
The Ministry of Labour’s investigation determined that one of the key contributing factors to the incident was the company’s failure to use a wire guide on the de-tensioning end of the cable strands as required by the manufacturer of the de-tensioning equipment.
Because no wire guide was in place, the anchor plates slid from their supports and failed.
Failure to use the required wire guide constitutes a contravention of the Occupational Health and Safety Act, which says that employers must take every precaution to protect the worker.