The rules affecting interstate truckers and bus drivers will take longer to put in place and may be more nuanced.

Image Department of Transportation Secretary Ray H. LaHood on Thursday announced the measures aimed at curbing what he called a deadly epidemic of distracted driving. Credit... Luke Sharrett/The New York Times

Mr. LaHood said the rule would “ban text messaging altogether” by such drivers. But Rose A. McMurray, acting administrator for the Federal Motor Carrier Safety Administration, which regulates the trucking industry, said there would first need to be a definition of “text messaging.”

The question facing the trucking industry in particular is what will become of the computers that thousands of long-haul truckers use in their cabs to communicate with dispatchers and do other work.

Research from the Virginia Tech Transportation Institute shows that these devices can markedly increase the risk of causing a crash or near crash if used when driving. Its research also shows that truckers often bypass warnings to not use the devices while driving.

Ms. McMurray said she expected that it would take several months to complete a rule governing buses and trucks, during which time the agency would study the “array of devices” used by these drivers.

She said that she expected to ban truckers from texting with their phones and also to ban behavior “that would require fingers to manipulate a keyboard, or to take the eyes off the road” to use a keyboard and, possibly, other technologies used for typing.

The trucking industry has said it is concerned that texting bans in general could have unintended consequences of interfering with devices that truckers have come to rely on.