At the heart of the highway crash that severely injured comedian Tracy Morgan and three other passengers and killed another comedian is this: The truck driver who plowed into Morgan's limo had not slept for 28 hours before the collision.

A federal investigation found Kevin Roper's fatigue probably caused last year's accident in a work zone on the New Jersey Turnpike. That makes all the more incomprehensible the U.S. Senate's passage last month of a bill that would exempt some truck drivers from rules adopted in 2013 to set mandatory rest periods and limit the hours they can work. The rules reduced both fatigue and crashes. The Senate bill can't become law.

advertisement | advertise on newsday

The National Transportation Safety Board found other troubling issues: Walmart Transportation LLC, Roper's employer, has no fatigue management program to monitor and help drivers, as recommended by the NTSB. Roper drove 12 hours from his Georgia home to a Walmart distribution center in Delaware to begin work and was 131/2 hours into his 14-hour duty day when he plowed into the limo in a work zone. None of the limo's passengers wore a seat belt and the limo company did not remind them of that requirement; the NTSB said their serious injuries were partly a result of not being buckled in.

Customizing the limo van left it with only one side door for escape or rescue, and that was rendered inoperable by the crash. It took nearly 40 minutes for emergency responders to cut through plywood panels in the limo's walls to get the victims out.

Our roads are dangerous. We know that. Despite recent progress, more than 30,000 people still die in motor vehicle accidents in the United States every year. One in 7 die in crashes involving large trucks, like the one that smashed into Morgan's limo. Many of us have had our own scary close encounters with these big rigs.

The NTSB report shows many areas where steps can be taken. But we should start with a step we should not take. Rules on work hours and rest for truckers must remain intact and enforced. Because chances are Morgan and his fellow passengers would have had an uneventful trip up the New Jersey Turnpike if Roper had gotten enough sleep.