NEW BRUNSWICK, N.J. >> A truck driver’s lack of sleep is being blamed for the highway crash that injured Tracy Morgan and killed another comedian in New Jersey.

As Morgan recovered in a hospital, authorities said Monday that the truck driver who triggered the weekend crash hadn’t slept for more than 24 hours before the accident.

Wal-Mart trucker Kevin Roper is expected to appear in state court Wednesday. It was unclear if Roper, of Jonesboro, Georgia, had retained an attorney. He remained free after posting $50,000 bond.

Authorities said Roper apparently failed to slow for traffic ahead early Saturday in Cranbury Township and then swerved to avoid a crash. Instead, they said, his big rig smashed into the back of Morgan’s chauffeured limo bus, killing comedian James “Jimmy Mack” McNair and injuring Morgan and three other people.

Roper has been charged with death by auto and four counts of assault by auto. Under New Jersey law, a person can be charged with assault by auto if he or she causes injury after knowingly operating a vehicle after being awake for more than 24 hours.

According to the criminal complaint, Roper operated the truck “without having slept for a period in excess of 24 hours resulting in a motor vehicle accident.” It doesn’t specify the basis for that assertion.

The accident occurred in a chronically congested area of the New Jersey Turnpike where a five-year widening project is expected to finish this year. A turnpike authority spokesman said two of three northbound lanes had been closed about a mile ahead of the accident for road work, which likely slowed traffic.

Spokesman Tom Feeney said turnpike officials haven’t seen an increase in fatal accidents in the construction area, which stretches about 35 miles.

Morgan, a former “Saturday Night Live” and “30 Rock” cast member, was in critical but stable condition Monday. His spokesman, Lewis Kay, said he faces an “arduous” recovery after surgery on his broken leg.

Morgan suffered a broken femur, a broken nose and several broken ribs and is expected to remain hospitalized for weeks, Kay said. Morgan’s fiancee was with him at the hospital, he said.

Wal-Mart Stores Inc. President Bill Simon said the Bentonville, Arkansas-based company “will take full responsibility” if authorities determine its truck caused the accident.

Wal-Mart trucks have been involved in 380 crashes in the past two years, federal data show. The crashes have caused nine deaths and 129 injuries. The company has 6,200 trucks and 7,200 drivers, according to the Federal Motor Carrier Safety Administration, and they drove 667 million miles last year.

Roper’s truck was equipped with a system designed to slow its speed and notify him of stopped traffic ahead, a company spokeswoman said. It’s unknown if the system was working.

The National Transportation Safety Board is working with state police to look at any issues in the crash related to commercial trucking and limousine safety.

Federal regulations permit truck drivers to work up to 14 hours a day, with a maximum of 11 hours behind the wheel. Drivers must have at least 10 hours off between work shifts to sleep.

Wal-Mart said it believed Roper was operating within federal regulations.

“Safety is the absolute highest priority for Walmart,” it said in an emailed statement.

Safety advocates said they hope the accident will help their case.

“This is part of a systemic problem of having tired people driving at night and driving large trucks,” said Henry Jasny, vice president of Advocates for Highway and Auto Safety.

But Dave Osiecki, vice president of the American Trucking Association, said no regulations can prevent a driver from making “bad choices.”

Morgan, a New York City native, was returning from a standup performance at Dover Downs Hotel & Casino in Delaware when the crash occurred. Six vehicles were involved in the pileup, but no one from the other cars was injured.

McNair, of Peekskill, New York, was a close friend and mentor to Morgan, Morgan’s ex-wife told the New York Daily News.

Associated Press writers Joan Lowy in Washington, D.C., and Dee Ann Durbin in Detroit contributed to this report.