BOSTON --- After a trolley driver admitted to police that he was texting his girlfriend just before a May 8 collision, the head of the Boston area transit authority vowed to ban all train and bus operators from even carrying cell phones on board.

Approximately 50 people were injured in the underground collision in downtown Boston, though none of the injuries is considered life-threatening, the Associated Press reported.

The Massachusetts Bay Transportation Authority forbids operators from using cell phones on the job. An internal ad campaign has even featured a poster of an open cell phone that warned employees not to drive "under the influence."

But Daniel Grabauskas, the agency's general manager, acknowledged on Saturday that some employees just can't resist the temptation when their cell phone is within easy reach.

"I want to remove any temptation by one or two people stupid enough to think a moment of convenience is worth the lives of the people they're transporting," Grabauskas said.