At first, it was unclear what work the agency had performed to allow trains to resume full-speed travel, but an MBTA official told the News Service that crews spent several recent nights widening sections of the rails to address the narrowness problems.

Source: https://www.bostonherald.com/2023/10/12/mbta-workers-widened-faulty-green-line-tracks-in-early-morning-operations/

NCA CEO Sally Barnes said ACT officials working on the project had flagged that the narrowness of the road veering left into State Circle from Commonwealth Avenue could pose engineering and cost challenges.

Source: https://the-riotact.com/nca-to-investigate-light-rail-route-switch-back-through-parliamentary-zone/678031