the present station. The line would be constructed using two TBM tunnels, deep, along with cut-and-cover in Fort Point Channel. Underground South Station would be built in Fort Point Channel, east of surface station. Central station would connect to the Blue Line at Aquarium station. The Blue Line is currently the only MBTA rapid transit line with no direct connection to the commuter rail network. Estimated cost: $21.491 billion. Central Artery two-track Same route as Central Artery four-track but has no Central station. Constructed using one TBM tunnel, deep, with cut-and-cover used in Fort Point Channel. Underground South Station would be built in Fort Point Channel, east of surface station. Estimated cost: $12.317 billion. South/Congress alignment North Station would be entirely underground and moved several blocks south, to between State and Haymarket Streets; no Central station. Stacked tracks and platforms are incorporated within a single TBM bored tunnel, deep. Underground South Station would be north-west of surface station. Estimated cost: $13.181 billion. Pearl/Congress alignment North Station would be entirely underground and moved several blocks south, to between State and Haymarket Streets; no Central station. Tracks would be in two TBM bored tunnels, deep. Underground South Station would be north of surface station. Estimated cost: $14.388 billion. Electrification The tunnels would not be able to handle diesel locomotives and therefore would require the use of dual-mode locomotives or the electrification of several MBTA commuter rail lines. Full electrification of additional rail lines, proposed in earlier studies, could help Massachusetts and the MBTA reach their greenhouse-gas reduction goals, make service more reliable, allow trains to accelerate more quickly, and reduce travel times, but it is expensive and only limited electrification is included in the 2018 proposals. Part of the Fairmount Line would be electrified to allow Amtrak and MBTA Northeast Corridor trains currently routed through Back Bay to reach South Station during construction of the Back Bay portal. The electrified service region would also incorporate the proposed South Coast Rail project's Phase II, which includes electrification to Fall River and New Bedford. Benefits The 2018 feasibility study modeled ridership in 2040 based on various scenarios. In regular service, the two-track options would increase all day boardings to 195,000 compared with 150,000 in the no-build scenario. Assuming an upgrade to all-day peak service, the two-track options would increase all day boardings to 225,000 compared with 195,000 with the South Station expansion. Overall, NSRL