WASHINGTON , D.C. - The acting chairman of the National Transportation Safety Board testified before a House Transportation and Infrastructure's Subcommittee on Railroads that school bus accidents and fatalities will continue to occur at passive grade crossings as long as audible train warning systems remain inadequate.

"The sound of a train horn is effective as a warning only if the driver recognizes it as a train horn and takes appropriate action," Mark Rosenker told congressman on July 21.

He said that placing a stop sign at a passive crossing, a clear, unambiguous message is sent to the motor vehicle driver of the location of the crossing is and what action must be taken.

The NTSB learned while investigating the 1995 Fox River Grove and 2000 Conasauga , Tenn., accidents that noise levels such as defrosters, air conditioners, wipers, or radios inside a school bus, or any other vehicle for that matter, affect the driver's ability to recognize an approaching train's warning horn. Other factors include soundproofing designed to cut down on engine, transmission, road and exterior traffic noise.

"In the Fox River Grove accident, our tests indicated that the train was only about 100 feet or 1.1 seconds from impact when the train horn sound exceeded the ambient noise levels at the driver's seat by 3 to 5 dB," he added. "In the Conasauga accident, the Safety Board concluded that the driver had difficulty detecting the train horn at all, and was probably unaware of the presence of the train."

For both accidents, the NTSB recommended that radio speakers adjacent to the drivers' heads be disconnected.

He told subcommittee members that, in both accidents, the train horns functioned properly and were sounded well in advance of the crossings and up to the crossings. In each case, the doors and windows of the buses were closed, radios were playing and the bus ceilings were at least partly covered with sound attenuating panels. These panels are capable of reducing sound as much as 25 dB in a bus when compared to a bus without attenuating panels.

NTSB Managing Director Joe Osterman told NSTA members at the organization's 41 st Annual Convention earlier in the week that, in such collisions, seating and the lack of three-point lap belts are also major safety concerns.

"Separation of the school bus body and chassis is not the problem, as students benefit from a better 'ride down' of the accident forces," he said, explaining that the collision trauma is actually dissipated.

Instead, he said NTSB wants to see NHTSA redesign school bus seats with contours to accommodate better occupant protection and mandate use of three-point lap/shoulder belts.

"The seats in a school bus today were not designed for seat belts. If NHTSA does re-engineer the seats, then we would want to have mandatory use laws because (seat belt/occupant protection) is recommended for all other vehicles," said Osterman.

Reprinted from the September 2005 issue of School Transportation News magazine. All rights reserved.