A Wal-Mart truck driver who hadn't slept for 28 hours caused a crash which left Tracy Morgan severely injured, the National Transportation Safety Board has ruled. Kevin Roper hadn't slept for 28 hours and failed to adhere to warning signs to slow down before the crash on the New Jersey turnpike in June 2014, but the board added that the '30 Rock' star and other passengers' failure to wear seatbelts and adjust headrests in their limousine van also played a role in the severity of their injuries, as most were a result of them hitting the sides of the vehicle. The board - who presented their findings at a public hearing in Washington concluded that if Roper had slowed to 45mph he would have been able to stop before impact and avoided the crash, which left James 'Jimmy Mack' McNair dead and four others severely injured. The board's chairman, Chris Hart, said: ''One tragic aspect of roadway death is that so often they could have been prevented.'' Roper's attorney, David Glassman, insisted his client had not gone without sleep for 28 hours. He said: ''Not only are we disputing it, it is factually wrong.'' The driver had worked for the company for 15 weeks and had nine ''critical event reports''. The reports were produced by the truck's computers and kept track of hard braking, activation of the vehicle's stability control system and other instances that point to unsafe driving. He was also involved in a separate accident that was deemed to be preventable, resulting in the driver losing his safety bonus. Following the crash, Morgan was left with a broken leg and was in a coma for two weeks, but is making a slow recovery. He said recently: ''I'm happy to be alive. I have my good and bad days...I just want to get better and become healthy.''..