A Transportation Department agency closed the motorcoach companies as part of Operation Quick Strike, an eight-month investigation of 250 bus lines it deemed to be the riskiest operators.
In 2011 the number of fatalities per vehicle miles traveled was the lowest ever, the Department of Transportation said. Technology and education are credited with the improved US road safety.
An explosion caused by a fuel truck crashing into a bridge in Saudi Arabia poses the question: What measures are in place to prevent fuel truck accidents in the US?
US regulators had begun work to suspend operations of the Sky Express bus line even before a company bus flipped over Tuesday on an interstate highway in Virginia, killing four.