The Grand Arc Project, my selection of a name for a project constructing a D.C. North Mall/Enclosed filtrated Underground North Central Freeway (electronically tolled Expressway), offers the tantalizing opportunity to add a new WMATA line along New Hampshire Avenue into Maryland.
Since the existing WMATA Red Line would be rebuilt underground, we have the opportunity for creating a new two track WMATA line spur, beneath the hill at New Hampshire Avenue, between the RR corridor and the DC-MD line. Such a line would connect to and from the south with the Red Line, and the Grand Arc Project's inclusion of reconstructing the railroad underground provides opportunity to increase the number of WMATA as well as MARC/CSX tracks. Squandering the opportunity would be unacceptable, and neglects the fundamental stage-ability: of starting with this new spur, at least to its nearest station, somewhere in Maryland, between the District line and the vicinity of Sheridan Street. This is essentially a two block long segment of the 6 lane New Hampshire Avenue commercial strip zone, and a prime candidate for re-development. This initial stop would be called Sheridan Station.
This entire initial segment, including the portion within the District, would be underground.
To the north, where the topography descends into the valley at Ray Road, its extension would transition to a bridge, perhaps as a lower level of a new span for carry New Hampshire Avenue over the valley. Past that, it would enter its second tunnel segment to pass beneath the log established parking lot of Giant Supermarket
Have a second station in the southeast quadrant of the next main commercial area at the intersection with 410 East West Highway. Likewise, place that segment underground. Be sure to guarantee a guarantee of rent stabilization for the existing businesses in the strip malls, within the first level of the inevitable replacement development.
Owing to the topography, of the valley at Ray Road, this line could emerge upon its own narrow viaduct, and if a bridge was constructed to place New Hampshire Avenue atop that valley, place the new WMATA line as its lower level. Have it transition to tunnel (cut and cover) extending beneath the existing Wendy's and north past East West Highway (Rt 410).
Where the topography again descends, either have it elevated, perhaps above the median of New Hampshire Avenue, or optionally, continuing it as trench & cut and cover, to a cut and cover segment towards and at the northeast quadrant of New Hampshire Avenue's intersection with University Boulevard, at the site of this line's 3rd initial stop- University Avenue Station.
Initial project would stop here, with its design fully anticipating a further continuation along New Hampshire Avenue to White Oak, by the U.S. F.D.A. Center, with the initial portion of a subsequent extension along the wide 6 lane expressway spec Route 29, with the next stop being at the commercial area alongside Rt 29 just south of Cherry Hill Road- fairly near to the Rt 29 interchange with MD 200/ICC Inter County Connector.
As an option, examine the use of moled tunneling, to start near the DC/MD line, to see if such could extend under the various valleys.
Construction of the Grand Arc Project would provide some added rail capacity alongside the underground vehicular expressway, with the WMATA & MARC/CSX RR, each improved from 2 to 3 track operation.