Red Bridge
The GLX begins at the north end of the Lechmere Viaduct, with a new elevated line continuing north for about parallel to the O'Brien Highway. The former surface-level Lechmere station will be replaced by an elevated station on the new alignment. The two branches split with an aerial flying junction on the Red Bridge viaduct in the Inner Belt area. The Union Square Branch runs west from Red Bridge, sharing the Fitchburg Line right of way. The Medford Branch runs northwest from Red Bridge, sharing the Lowell Line right of way. Like the existing D branch, the new branches are fully grade-separated, with no level crossings. A new vehicle storage yard and maintenance facility is located in the Inner Belt area, with leads from both branches at Red Bridge. An extension of the Somerville Community Path runs along the Medford Branch south of Lowell Street, with a high bridge carrying it above the Red Bridge viaduct.