MBTA The MBTA on March 23 announced that Phases 1 and 2 of critical signal modernization work taking place on the Red Line at Columbia Junction have been completed ahead of schedule, and Phase 3 will begin on March 26 for approximately two weeks. During Phase 3 of this critical signal work, beginning at approximately 8 PM through the end of service each day, northbound and southbound Braintree branch riders will need to transfer to an Alewife-Ashmont train at JFK/UMass for continued service beyond JFK/UMass. Crews are completing the testing and cutover of the new, digital signaling system at Columbia Junction near JFK/UMass. This work, MBTA says, “brings important upgrades that will strengthen Red Line service reliability for riders, providing the ability to route trains more quickly, turn trains around faster, and recover from unplanned disruptions more efficiently.” In order to test the new signal equipment and cutover to the new system, the remaining temporary service changes outlined here will be in place beginning at 8 PM through the end of service every day. Phases 3 and 4 are anticipated to last approximately two weeks each but may adjust slightly based on the work being completed. Any timing adjustments will be made public in advance on T-Alerts. Columbia Junction is the complex area of track just north of JFK/UMass that merges the Ashmont and Braintree branches and connects the Red Line’s main passenger track to the Cabot Yard Maintenance Facility where the majority of the Red Line fleet is stored…