BOSTON – A subway crash allegedly caused by a driver distracted with text messaging resulted in swift and tough penalties for MBTA trolley, bus and train drivers, yet lawmakers have been slower to adopt similar cell phone restrictions for Massachusetts automobile drivers.

Since the May 8, 2009, crash, 18 MBTA workers have been disciplined for using or carrying cell phones on the job, a violation of a policy enacted little more than a week after the accident. Ten have been fired, including three the same day Richard Davey took over as general manager in March.

“You don’t like to fire 22-year veterans,” Davey said Friday, referring to one of those terminated under the ban. “But with that said, safety is my top priority. And that’s what I’ve been hired to do: improve the safety of the authority. And we have a zero-tolerance policy when it comes to using these devices on our equipment.”

The Massachusetts House and Senate, though, continue to negotiate the terms of a texting ban for automobile drivers, despite a series of fatal accidents involving everyone from teen to elderly drivers.

The bill is hung up over a House provision that would require the use of handsfree cell phones, and a Senate requirement that motorists 75 and older be medically screened regularly to maintain their license.

House Speaker Robert DeLeo told The Associated Press a merged bill focused on overall driving safety will pass the Legislature before the session ends on July 31.

“That’s not going to get lost in the end-of-the-year shuffle,” DeLeo said.

The T accident occurred as a 24-year-old Green Line operator, Aiden Quinn, was typing a text message on his cell phone, according to phone records, transportation documents and witness testimony.

As Quinn was texting, authorities said, he ran through yellow and red warning lights and into the two-car train ahead of him between the Government Center and Park Street stations.

Investigators said 62 passengers on both trains received medical attention, with 49 taken away in ambulances. The crash caused an estimated $9 million in equipment damage.

Quinn was fired and indicted on a felony charge of grossly negligent operation. He faces trial in October, but a Suffolk Superior Court judge must still hear several motions, including one to dismiss.

Jamie Sultan, one of Quinn’s attorneys, said authorities inappropriately charged him under a statute focused on railroad operations, since all other potential charges were misdemeanors.

After the accident, the Massachusetts Bay Transportation Authority enacted a strict policy requiring any operator caught using a cell phone on the job to be suspended for 30 days, with a recommendation that he be fired. An operator caught carrying a cell phone while working is suspended for 10 days.