At 6 p.m. on June 6, 1975, a southbound tractor-semitrailer (truck) collided with a northbound intercity-type bus near Hamilton, Georgia. The bus was the second vehicle of a four-vehicle convoy. Two southbound automobiles were waiting for the convoy to pass before the first could turn left into a driveway. The truck was following the automobiles; when the truckdriver attempted to avoid the cars, his truck jackknifed and collided with the bus. The vehicles collided on a two-lane highway in a sparsely populated, rural area; a light-to-moderate rainshower was in progress. The truckdriver and busdriver were killed in the collision and 19 of the 20 bus passengers were injured. The National Transportation Safety Board determines that the probable cause of this accident was the failure of the truckdriver to operate at a proper speed and with a proper level of attention to and concern for safe driving.