BOSTON (CBS) – The city of Boston is being put on notice about legal action on behalf of a man seriously injured in a South Boston intersection on September 11, his girlfriend struck and killed. It was a tragedy under any circumstances, but for Warren Cheng it’s compounded by the fact he was going to propose to her in a matter of days. “Devastating, devastating, a woman he was planning on marrying. She was the one,” said Cheng’s attorney Jeff Catalano.

The accident happened September 11 as the couple crossed at the intersection of Summer and Melcher Streets, on their way to a dinner to meet friends in the Fort Point neighborhood. Residents had complained for months about a traffic light that turns green for vehicles, while pedestrians are still allowed to cross.

“This is not a freak accident, it didn’t happen out of the blue,” Catalano said. “The city was on repeated notice from citizens and a multitude of people to do something before someone gets killed.”

In a letter notifying the city of a lawsuit, Catalano cites several notices through the 311 citizens reporting system of residents warning “someone WILL get hit” and “someone is going to get hurt here” and receiving a blanket response. “The city repeated a blanket response that we’re following guidelines and nothing can be done about it,” said Catalano.

Boston Mayor Marty Walsh insists the city had been looking at making changes at the intersection as part of a comprehensive safety plan. Changes to the traffic signals were made two days after the accident.

“At this particular intersection and other intersections plans were being drawn up to make changes and fix the intersection, we weren’t just responding to it,” said Walsh.

Diane Ly’s family has released a statement, “Her passing has left a hole in the lives of those around her that will never be filled. No more weekly visits, no more holidays shared with her extended family. The future she was building with Warren abruptly came to an end.”

The question now is could it have been prevented. The city has six months to respond to the letter.