WASHINGTON, D.C. — Federal investigators say several factors, including the bus driver’s lack of familiarity with the handling of the vehicle, were involved in the fatal crash of a school bus in Omaha, Neb., in October 2001.

But the probable cause of the crash was the failure of the Nebraska Department of Roads to recognize and correct the hazardous condition in the work zone where the accident occurred, according to a report issued by the National Transportation Safety Board (NTSB).

The crash occurred on Oct. 13, 2001. A 78-passenger school bus was traveling west on U.S. Route 6 when it swerved to avoid a motorcoach traveling in the opposite direction. The school bus left the road, broke through a barrier and went off a bridge. It fell 49 feet into a small creek. Three high school students and one adult were killed in the crash. More than two dozen other students suffered minor to severe injuries.

In addition to the problems created by the work zone — attributable to the irregular geometry of the roadway, narrow lane widths and the high speed limit — NTSB investigators said the failure of the barrier system to keep the bus from leaving the road contributed to the severity of the accident. They concluded that the barrier system should have deflected the bus back into its lane, avoiding its spill over the side of the bridge. NTSB officials said the school bus driver’s apparent lack of familiarity with the vehicle contributed to the crash. The driver, a 22-year-old college student, had just started his third year driving for Seward School District and normally drove a 1991 59-passenger Thomas conventional bus. He had driven the 78-passenger transit-style bus involved in the crash only three or four times in the previous two years.

NTSB officials also cited the students’ lack of emergency preparedness, which resulted in confusion as they tried to exit the mangled bus. “Had the Seward School District conducted emergency evacuation drills and demonstrations for all students, the passengers’ ability to open emergency exits and evacuate the vehicle in an emergency would have been greatly improved,” the report said.

Among other things, the board recommended that the National Association of State Directors of Pupil Transportation Services prepare a report that can be used by its members to influence their state officials to require pre-trip briefings before school-related activity trips on school buses or school-chartered buses. The NTSB also recommended that the state directors association develop criteria for such briefings that would include training all students on the location and use of emergency exits.

Emergency response efforts were hampered by inadequate communications and a lack of preparation in school bus extrication, the report also said.