WASHINGTON, D.C. — U.S. Transportation Secretary Ray LaHood today announced federal guidance to prohibit texting by drivers of commercial vehicles such as large trucks and buses.

The prohibition is effective immediately and is the latest in a series of actions taken by the Department of Transportation (DOT) to combat distracted driving since LaHood convened a national summit on the issue in September.

“We want the drivers of big rigs and buses and those who share the roads with them to be safe,” LaHood said. “This is an important safety step, and we will be taking more to eliminate the threat of distracted driving.”

The action is the result of the DOT’s interpretation of standing rules. Truck and bus drivers who text while driving commercial vehicles may be subject to civil or criminal penalties of up to $2,750.

In an e-mail to members Wednesday, the National Association of State Directors of Pupil Transportation Services said that the federal guidance "does not apply, technically, to most school bus operators who are exempt from most FMCSRs [Federal Motor Carrier Safety Regulations]."

However, during the September summit on distracted driving, LaHood announced that there would be a forthcoming federal rulemaking seeking to disqualify school bus drivers convicted of texting while driving from maintaining their commercial driver’s licenses.

The Federal Motor Carrier Safety Administration (FMCSA) said in a press release that it is working on "additional regulatory measures" on the use of electronic devices while driving, and that those measures will be announced in the coming months.

Some states specifically prohibit school bus drivers from using cell phones — hand-held or hands-free — and some states prohibit all drivers from using hand-held cell phones or just from texting.

FMCSA research shows that drivers who send and receive text messages take their eyes off the road for an average of 4.6 seconds out of every 6 seconds while texting. At 55 miles per hour, this means that the driver is traveling the length of a football field, including the end zones, without looking at the road.