A Milton senator wants legislators to wield their oversight authority and examine delays in upgrades to the MBTA's Mattapan Line.

Sen. Walter Timilty has asked the Senate Committee on Post Audit and Oversight to conduct an oversight investigation about how the T has handled the Mattapan Line Transformation project, a three-phase effort to extend the lifespan of the decades-old trolleys, improve station and rail infrastructure, and prepare to roll out a new vehicle fleet.

"In my opinion, the MBTA has failed to meet the needs of the people of the Commonwealth, for whom this transportation serves as a lifeline each and every day," Timilty said on Monday. "This transformation project has encountered multiple delays and is currently more than two years behind schedule. This is both unacceptable and frustrating."

Timilty also said he has not heard of a target date to complete repairs to the staircase at the T stop in his hometown of Milton. The project's opening salvo called for $7.9 million in fleet improvements such as modern propulsion, braking equipment and repairs to the historic trolleys, which date back to the 1940s. Officials projected the work could extend the existing fleet's service life by eight to 10 years.

Before COVID-19 disrupted ridership patterns, the 2.6-mile Mattapan Line transported about 6,600 riders every day, serving eight stations between the Red Line's Ashmont endpoint and Mattapan. In a lengthy statement, an MBTA spokesperson said Monday that the project ran into "a number of obstacles," including COVID-19 outbreaks that affected the available workforce at the Everett maintenance facility, structural issues on the vehicles, and the presence of lead paint.

"The discovery of lead paint during sandblasting required an immediate halt to the vehicle work and mitigation of lead paint in the trolley work area at the Everett repair shops," MBTA spokesperson Joe Pesaturo said. "The discovery resulted in a one-year delay in the project until an outside contractor could be found to help address the lead paint issue." Pesaturo said the T plans to place the first rebuilt Mattapan Line car into passenger service this winter, followed by the summer for the second car and "then another rebuilt car every five months until all eight are available for service." Officials originally aimed to finish the trolley upgrades in 2019.