(RALEIGH) -- After a spate of deadly tour bus accidents, the federal government is launching a national crackdown on companies with a history of problems. It will include safety sweeps over the next two months.

Transportation Secretary Ray LaHood says DOT needs the help of law enforcement and safe bus operators to get the bad drivers out from behind the wheel,

"A lot of the people that ride these buses are vulnerable because they just assume that everything is okay. We have to be vigilant about this."

In January the driver of a a Charlotte-based Sky Express bus en route from Greensboro to New York, that crashed in Virginia killing four, was sentenced to serve six years in prison on four involuntary manslaughter convictions. This dispatcher was also charged.