Abstract: Employee #1 and a coworker, of the Oregon Department of Transportation, were putting out signs on the northbound side of I-5 at Milepost 159. The coworker headed to the center barrier and erected his sign. Employee #1 parked her vehicle on the shoulder, approximately 20 ft behind the coworker's vehicle. She was standing in front of her vehicle erecting a sign in a holder on the guardrail when an empty tanker truck with a 40 ft and a 25 ft trailer, traveling at 57 mph, ran into the rear of Employee #1's truck. Employee #1 was hit by her truck and thrown over the guardrail. The truck then pushed the rear vehicle into the front vehicle. Employee #1 sustained very serious injuries to both legs and her head. She was hospitalized.