Detectives from the Washington State Patrol on Monday released the findings of an investigation that determined that the truck that hit the I-5 Skagit River Bridge in May 2013, leading to its collapse, was 2 inches over-height.

They found the truck was permitted to carry a load of no higher than 15 feet, 9 inches. After the collision, investigators noted the load measured 15 feet, 11 inches. The over-height load struck 11 of the bridge’s overhead sway braces as it crossed the span.

The collision happened on May 23, 2013, shortly after 7 p.m. After the collapse, two vehicles fell into the river and the occupants had to be rescued. They suffered non-life threatening injuries and have recovered. The bridge has since been repaired.

Detectives also determined that the pole carried by a pilot car hit the bridge structure, which should have triggered a warning. However, the driver of an over-height load is the person legally responsible for safe transit, not the driver of any support vehicle or pilot car, according to the Washington State Police.

Truck driver William D.W. Scott with Mullen Trucking of Alberta, Canada, was cited WSP for negligent driving in the second degree, which is a traffic infraction carrying a fine of $550. He reportedly still works for the carrier. A hearing over the fine is set for July 2015.

The report states Scott should have moved into the center lane of the bridge, which would have accommodated even the over-height load. Investigators determined only four seconds passed between the time the pilot car’s pole hit the bridge and the truck’s load hit the first sway brace. The truck was following approximately 350 feet behind the pilot car. Scott told federal investigators a truck heading in the opposite direction made it difficult for him to move to the center of the bridge.

A report issued by the National Transportation Safety board in July also placed the blame for the bridge’s collapse on the truck. However, the NTSB report noted the Washington State Department of Transportation was also at fault due to deficiencies in its system intended to safeguard the passage of oversized loads over state roadways.

The detective’s report of investigation is available on the WSP website.