multiple units for the Fairmount Line, new Track 61 service, and several other lines with the new service being labeled as the Indigo Line. The DMU procurement as well as the Indigo Line proposal was canceled in 2015. In 2021, the MBTA indicated plans to pilot electric multiple units on Providence service (on the Northeast Corridor, which is already electrified for Amtrak service) in 2024, with the Fairmount Line and the inner section of the Newburyport/Rockport Line electrified later in the decade. Several preliminary projects, including planning for a new layover facility, are scheduled for fiscal years 2023 to 2027 – but not actual electrification. By 2022, lawmakers and environmental advocacy groups had criticized recent MBTA proposals for not adhering to previously set rail initiatives. In June 2022, the MBTA indicated plans to purchase battery electric multiple units, with catenary for charging on part of the network. This is intended to reduce the amount of catenary installation required, avoid reconstructions of overhead bridges, and avoid poor existing power grids on some branch lines. Plans call for electric service on the Providence/Stoughton Line and Fairmount line by 2028–29, followed by the Newburyport/Rockport Line in 2031; all lines would be electrified by 2050. Pilot electric service between Boston and Providence would be possible after the late 2023 introduction of the Avelia Liberty freed up ACS-64 locomotives for use. Funding for electrification of the Framingham/Worcester Line was included in a 2022 state bond bill. Transit advocates have expressed concern that a hybrid service plan remains unproven for regional rail applications and could be more expensive to operate than full-build electrification; others have criticized that the MBTA's cost and construction projections for system-wide catenary installation were overestimated in comparison to similar project costs in Europe and North America. North–South Rail Link No direct connection exists between the two downtown commuter rail terminals; passengers must use the MBTA subway or other modes to transfer between the two halves of the system. (For non-revenue transfers of equipment, the MBTA and Amtrak use the Grand Junction Branch.) The proposed North–South Rail Link would add a new rail tunnel under downtown Boston to allow through-running service, with new underground stations at South Station, North Station, and possibly a new Central Station. A feasibility study was conducted in 2018. South Coast Rail The South Coast Rail project is under construction to extend service to the South Coast cities of