As it pertains to a section of the Mattapan trolley line, the MBTA is closing the barn door after the horse has bolted, so to speak.

The quaint 1940s orange and cream-colored Mattapan trolleys begin their 2.6 mile, 10-minute, 8-stop journey in Mattapan and end up at the Ashmont Station, then bang a uey and make the return trip to Mattapan. Along the bumpy way, the trolleys cut across Central Avenue at the border of Dorchester and Milton. There is a stop sign there for automobiles crossing over from Dorchester into Milton, but not so in the opposite direction. That is about to change as a result of an accident and an inquiry to the T from a reporter.

In April, a car going from Milton into Boston at the grade crossing whacked into a trolley. Let’s go to the police report:

“Prior to arriving at Central Station, she [the trolley operator] stopped and proceeded, not seeing any vehicles. [She] stated as she was crossing through the intersection, a vehicle that she did not see traveling west on Central Ave from Milton drove through the intersection, hitting the front of the trolley. . . . [A witness] stated he observed the trolley roll through the stop sign [for the trolley], not coming to a complete stop.”

Both vehicles sustained damage.

“[The motorist] was informed he was not being cited due to he did not have a stop sign and he had the right of way,” the police report notes.

In 2011, the Reporter noted that three other similar-type accidents had occurred at the Central Avenue grading. At the end of last week, Joe Pesaturo, the T’s communications director, was asked why there was still no stop sign going from Milton to Boston.

“A stop sign is to be posted no later than today,” he wrote back on Monday. And it was.