The truck driver charged with vehicular homicide and assault by auto after driving into a bus carrying comedian Tracy Morgan has pleaded not guilty to falling asleep at the wheel during an arraignment hearing.

Appearing at Middlesex County Superior Court, New Jersey on Wednesday (11Jun14), Kevin Roper, who is accused of causing the pile-up that cost comedian James MCNair his life and left Morgan and three others seriously injured, insisted he wasn't sleep-deprived behind the wheel of his Walmart truck.

In the criminal complaint, police stated Roper had been awake for more than 24 hours at the time of the crash. He failed to notice traffic slowing in front of him and hit Morgan's bus despite trying to swerve out of the way.

Roper's bosses at Walmart believe Roper was operating within federal rest guidelines.

Under New Jersey law, a driver can be convicted if there's proof he had been without sleep for 24 hours at the time of an accident.

Roper faces five to 10 years behind bars if prosecutors can prove he ignored sleep guidelines for a trucker.

Morgan remains in hospital after the crash.