BOSTON -- A collision between two MBTA trolleys that sent dozens of people to the hospital on Friday is estimated to have caused $9.6 million in damages, investigators said.

An MBTA driver told investigators that he was texting his girlfriend when the trolley he was operating slammed into the back of another Green Line car idling on the tracks.

The first trolley had been stopped for 1 minute and 40 seconds waiting for trolleys further ahead to clear the path, officials said.

The driver of the second trolley, Aiden Quinn, 24, of Attleboro, Mass., may face criminal charges in the crash. Quinn will be fired later this week if investigators verify that he was using his cellular phone before the crash, MBTA General Manager Daniel Grabauskas said. Quinn did not show up for a scheduled meeting with supervisors on Sunday, MBTA officials said.

National Transportation Safety Board investigators closed down MBTA service between Government Center and Park Street on Saturday while they used two trolleys to recreate the moments leading up to the crash. NTSB officials said that rear lights from the waiting train should have been seen in the dark tunnel 480 feet from the spot where it was struck.

Quinn’s car was traveling 25 mph when it careened into the back of the waiting train, officials said. It is unclear whether Quinn was braking immediately before the collision, but if the trolley’s speed was constant, the idling train would have been visible for at least 13 seconds before it was struck.

Investigators said that Quinn’s trolley also failed to stop at a red signal light 80 feet before the spot where the trolleys collided. The first trolley was pushed 31 feet down the tracks after it was struck.

At a press conference Sunday, NTSB officials said that their investigation of the incident should conclude sometime this week, but a full report on the crash will not be available for several months.

Two transit police investigators were seen entering Quinn’s home Saturday. A woman who answered the door at the home said he is sad about what happened.

Trolley operators were already banned from texting, but Friday’s crash near Government Center has triggered an even tougher new policy that will soon take effect: If train drivers are caught with a cell phone while working, they will be fired.

"If a zero tolerance policy on use of cell phones isn't sticking with our employees, then maybe we need to go to the next level," Grabauskas said.

Boston Carmen’s Union president Stephen Macdougall said the preventable accident does not reflect the behavior of most MBTA workers.

“The individual involved in last night’s incident and the issues led up to that tragedy were avoidable,” he said. “This was an individual act by an individual who does not represent the attitudes or the professional conduct of all or most MBTA workers.”

If Quinn was texting his girlfriend, he would be at least the 10th driver guilty of the offense in the last year.

In the last year, the transit agency has suspended at least nine other bus and trolley drivers for texting or talking on their cell phones while driving.