We transfer from the commuter rail platform to the heavy rail center platform. We will first go one station to the northern terminus at Oak Grove, and then return southward towards Boston. The narration will resume as we return southbound from Oak Grove. The layover here should be no more than seven minutes.
Oak Grove station is in the northern part of the city of Malden. As we begin our trip southbound, notice the commuter rail track on the eastern side of the right-of-way. Much of the line through Malden runs in a depression similar to the Southwest Corridor; however the Malden Center station sits on a high fill.
From just before to just after the Wellington station, you can see the Orange Line's shops on the right side of the tracks. Most of its equipment is stored and maintained here. A third track begins at Wellington, intended to be an express track, but it is rarely used. The next three stations have three tracks and two platforms.
Beyond Wellington, the now 4-track right-of-way (three transit, one commuter) crosses a bridge over the Mystic River. As we get closer to the city of Boston, the commuter line crosses under the Orange Line and meets up with other lines for their approach into North Station.
The Orange Line, meanwhile, runs underneath a double-decked freeway, I-93. It is this freeway that eventually will be underground once the Big Dig project is complete. The Sullivan Square and Community College stations sit underneath the freeway. If you look to the west about 1/2 mile away, you can see the elevated Green Line as it approaches Science Park and Lechmere. Much closer on the west side is the Boston Engine Terminal, a maintenance facility for MBTA commuter trains.
After Community College, the third track ends as we enter the downtown subway. We will pass under the Charles River and then stop at North Station. Besides a transfer to all North Station commuter rail lines, the Green Line stops here as well. Currently due to construction, one has to leave the system and access the Green Line on its elevated structure over Causeway Street. The platform where our train stops is part of the Superstation. Across this platform, southbound Green Line cars will stop in part of a new subway.
For now, a much easier transfer between the Orange and Green Lines can be made at Haymarket Station, where both lines run in the subway parallel to one another. That is where we will detrain.