An investigation found the train engineer had undiagnosed sleep apnea, and a National Transportation Safety Board investigation faulted NJ Transit for not following its sleep apnea testing guidelines, reports NBC 4 New York.

“This was a preventable catastrophe, and we and our clients are hopeful that NJT has now implemented and will continue to implement all the necessary safety improvement — systemwide, from rail operations to crew medical screenings — to protect its passengers, agency personnel, and the general public from harm,” attorneys Tom Kline and Robert J. Mongeluzzi, who represented the plaintiffs, said in a statement.