The National Transportation Safety Board said it lacked comprehensive data to establish a clear link between cell phone use and traffic accidents. But it said there's enough evidence to suggest that riders would be better off if drivers had one less distraction on the road.
"Professional drivers who have dozens of passengers' lives entrusted to them should devote their full attention to their task," said NTSB Chairman Mark Rosenker. "What we saw in this accident is appalling and could have resulted in great tragedy."
The NTSB called on the federal and state governments to pass rules barring cell phone use by motor coach and school bus drivers on the road, except in emergencies.
It also said all 50 states should have coding for "driver distraction" on traffic accident reports to help officials track the impact of cell phone use on driving. Currently 30 states have such codes.
The NTSB said the driver's "cognitive distraction" was to blame for the Nov. 14, 2004, accident after he failed to notice road signs warning of a low-clearance bridge because he was talking on a handsfree cell phone.
Operated by Eyre Bus Service Inc., the motor coach was carrying 27 high school students, a chaperone and a driver. It collided with the bottom of a bridge in Alexandria, Va., destroying the bus roof. Ten students received minor injuries and another sustained serious injuries.
Weather, the bus' mechanical condition and other factors did not play a role in the accident, and the driver was familiar with the route because he had driven the same path nine days earlier, the board stated in a summary of its investigation that was released Tuesday.
The NTSB called driver distraction the "probable cause" but also cited the low vertical clearance of the bridge, which does not meet current standards, as a contributing factor. The bus was 12 feet high, and was driving in the right lane, which had a 10-foot, 2-inch clearance. The left lane had a higher 13-foot, 4-inch clearance.
"These drivers have a special obligation to provide the safest driving environment possible for the passengers in their care," the board stated in its report.