Transportation Secretary Ray LaHood said Friday that surprise inspections of charter buses in the weeks leading up to this holiday weekend have resulted in more than 400 buses and drivers being pulled off the road for safety violations.

Congress held hearings this spring on increasing bus safety following two fatal crashes in New York and New Jersey this month that killed 17 people. In response, the DOT stepped up enforcement of existing safety regulations, working with officials in states to preform random inspections of buses.

Between May 1 and May 15, 127 drivers and 315 vehicles were given out-of-service citations, LaHood said Friday.

"During this heavy summer travel season, we will remain alert and remove from our roads any passenger bus or driver that places motorists at risk,” LaHood said in a statement.

DOT said it also had launched 38 compliance reviews of commercial bus rating, which are used to determine a company's safety rating. 

"The public deserves safe passenger bus transportation every ride,” Federal Motor Carrier Safety Administration chief Anne Ferro said in a statement. "FMCSA and its law enforcement partners will not rest until we weed out every unsafe passenger carrier and driver."

The department has proposed requiring bus drivers to get learner's permits before they can obtain commercial driver's licenses.