Abstract: At 12:30 p.m. on November 19, 2019, an employee working as a construction laborer for an commercial building contractor was working on a crew that had just finished installing a manhole at the bottom of an excavation. The next required task was to tamp down bedding gravel around the manhole at the bottom of the trench. Coworker #1 (Superintendent) had the jumping jack whacker in the back of his Chevy 2500 #WT-127 pickup truck. Coworker #1 backed the truck to the southwest side of the trench approximately 15 feet away from the edge. Coworker #1 directed Coworker #2, a Komatsu PC240LC Excavator Operator, to unload the jumping jack whacker from the back of the truck and into the trench so the crew could tamp the gravel. Coworker #1 then lined out the crew for 15 to 20 minutes before returning to his truck. Upon arriving at the truck, Coworker #1 noticed that his driver side WeatherTech floor mat was full of snow and other debris. He decided to clean the floor mat before continuing work. He slid back into the driver's seat and detached the floor mat from the truck floorboards. After clearing the debris from the mat, Coworker #1 replaced the mat without making sure it was properly latched in place. Coworker #1 then started to move the driver seat forward when the seat caught the unlatched mat and pushed it up against the accelerator. The truck was had been left in reverse gear after Coworker #1 backed his truck up to the trench to unload the jumping jack whacker. The truck started to move backwards towards the trench at which point Coworker #1 tried to enter the vehicle to stop it from going into the trench. Coworker #1 was unsuccessful and instead was thrown from the vehicle. The truck went into the trench striking the employee, who was operating the whacker at the bottom of the trench. The employee sustained chest fractures and was hospitalized.