Driverless forklift crushes warehouse worker at Washington bottler

What happened

A bottled water manufacturer in Washington State used driverless forklifts, known as laser guided vehicles, to move pallets around its warehouse. The vehicles navigated using vehicle-mounted lasers and reflectors and had safety sensors that stopped the vehicle and sounded an alarm when something was detected in its path.

On December 9, 2015, an alarm from one of the vehicles went out over the radio. A coworker who went to check found the 45-year-old dock coordinator slumped over the vehicle. The vehicle then began to move again, and the coworker pressed an emergency stop. The victim had severe chest and jaw injuries and was pronounced dead at a local hospital.

Investigators believe that a strand of plastic wrap had caught under the raised forks and tripped the obstacle sensor, and that the worker bent or knelt outside the sensor field to pull it free without first pressing the emergency stop. When the strand came away, the system registered the obstacle as cleared, resumed automatic operation and lowered the forks, crushing him against the wheel cover.

The system involved

A laser guided vehicle is a type of automated guided vehicle that carries pallets on forks without a driver. On this model, an obstacle detection stopped the vehicle only for as long as the obstacle was present. The manufacturer’s manual required workers to press an emergency stop before clearing anything, after which the vehicle had to be reset by hand. Without the emergency stop, it resumed its task as soon as the sensor was clear.

Investigation and response

The Washington State Department of Labor & Industries examined the death through its Fatality Assessment and Control Evaluation program, which is partly funded by NIOSH. Its narrative cites the state rule that workers must not be allowed under the raised part of a powered industrial truck.

The program recommended that employers build the manufacturer’s safety requirements into written procedures for automated guided vehicles, train workers on the specific hazards and insist the procedures are followed every time, and reinforce this with refresher training and spot checks.

What is not established

The narrative is based on preliminary data and says it is not a final determination of cause. The company, the vehicle manufacturer and the city are not named, and the report does not say whether the state issued citations.