​​​The truckdriver was unable to control the vehicle’s speed traveling down a steep, 4- mile downgrade toward a signalized intersection at State Highway 111 and U.S. Highway 127. She stated that she attempted to downshift into a lower gear. The driver failed to put the transmission back into gear, thereby descending the hill with only air mechanical brakes to control the speed. She lost control of the truck, traveled into the intersection, and struck several parked and moving vehicles and pedestrians. Two occupants of a car were killed; four other vehicle occupants and 13 pedestrians were injured.

The truckdriver stated during her interview with the police that her truck was overloaded (in excess of 93,000 pounds). A postaccident inspection of the truck revealed no mechanical deficiencies.

​​We ​determined that the probable cause of the accident was the truckdriver’s inability to control the truck on a long, steep downgrade. Contributing to the cause of the accident may have been excessive load weight. ​​