Friday, June 30, 2006

Room for Tunnel Access & Constructability?

Under the idea of deferring the tunnel, planning relies upon the idea of drilled (bored) rather than cut and cover tunneling: an option that is touted without consideration of soft soil conditions that may significantly increase the construction costs.

But it will still need an area for its inevitably cut and cover transition area for any ramp connections, perhaps at M Street as suggested by at least one of the year 2003 studies, and definitely at its north end with I-395.

Below is a map, created by The Washington Post, of that area's development.

Mouse over the numbered lots below for more information. The "'Near Southeast' D.C. Redevelopment" blog maintained by Post intranet editor Jacqueline Dupree also has dozens of photos showing changes in the neighborhood. A printable (PDF) version of this map is here.

area map

Related map:
Tracking the Development of a Neighborhood in Transition (Jan. 27, 2006)

GRAPHIC: Jacqueline Dupree and Nathaniel Vaughn Kelso, The Washington Post; Alyson Hurt and Brian Cordyack, - Aug. 15, 2005; updated Jan 17, 2006.

Note the plots at both these areas along South Capitol Street.

The stadium effectively blocks placing the tunnel east of South Capitol Street and west of 1st Street SE, unless it were to go under a portion of the stadium. This is not envisioned as part of constructing this stadium in relatively soft soil conditions quickly enough to open in time for an April 2008 opening. I have not found anything about any possible provisions in any of the building foundations for accommodating a highway tunnel.

Hence, the tunnel would have to either to the east, beneath 1St Street to CSX railroad properties for a continuation to I-395, directly beneath South Capitol Street, entirely or partially or entirely to the west, displacing existing residential dwellings.

If it were to not go to the west, and with planning seeking to eliminate the existing transitions near M Street by St. De Paul Church and Dominos Pizza, by process of elimination and such M Street area tunnel access would likely be along 1st Street SE. The parcels to the north of M Street have new development projects 80 M Street Wells Real Estate Investment Trust, office building completed 2001,First Street between M and L Streets, Faison Associates. The parcels to the south of M Street on the east side of 1st Street SE, ”First and M Streets” Cohen and Camilier families, are listed as a possible 700,000 square foot mixed use development, across a 1st Street from a Southeast Federal Center. One might ask if any of the existing planning studies outline any sort of right of way reservation for a northbound to surface ramp, or a southbound to tunnel ramp anywhere along this block of 1st Street SE between N and M Streets?

Any reference to a planned tunnel alternative as a common element of all three bridge proposals, to use the studies that presented this tunnel, and the reality of the Nationals Stadium, as guides, most likely means the option of an alignment directly beneath South Capitol Street. Together with the goal of eliminating the transitions to the underpass at M Street, this would plausibly translate to this new tunnel having no access ramps around M Streets. This would be regardless whether this South Capitol Street alignment tunnel was built by the drilled or strictly the cut and cover method.

But regardless of the method or the route, any such tunnel will require space for cut and cover segments to connect with I-395, with a design that anticipates a concurrent or future under grounding of the SW/SE Freeway with minimal cost and demolition.

Illustration: Jacqueline Dupree
Looking south from the SW/SE Freeway:
Ramps to I-395 just north of I Street

If it were to go under 1St Street SE, it would need to continue to the north of I Street SE through CSX owned railroad properties as essentially part of an all new underground interchange with a new underground SW/SE Freeway and the existing cut and cover I-395 Center Leg (3rd Street Tunnel. Connecting it to the existing ramps may be possible but would require additional temporary ramps: a less cost effective thing as about to be done at a cost of $47-118 million with the existing South Capitol Street viaduct.

Illustration: Jacqueline Dupree
Looking north to the SW/SE Freeway:
Ramps to I-395 just north of I Street

Having it beneath South Capitol Street, or somewhat offset to the west would be easier to connect with the existing I-395 ramps just north of I Street as an interim fashion before a future project for an underground SW/SE Freeway and interchange, but as an interim project that would include portions of the tunnel retaining walls for the future transition, hence allowing the grade to be further excavated later at reduced cost.

Given the general rule of maintaining traffic during the construction period, space is required to construct one “strip” of the right of way” while another “strip” of right of way or adjacent land is used to route traffic. With the existing I-395 ramps to the east side of South Capitol Street, the tunnel route would have to swing to the immediate east for the connection, and surface at I Street, with an open depressed transition southward to K Street and a cut and cover transition southward to L Street or further.

Today there is primarily open space along the east side of South Capitol Street from I Street southwards to the north wall of St. Vincent de Paul Church which sits at the northeast corner of the intersection with M Street. At I Street sits an Exxon gasoline station. At K Street sits a plot – 1000 South Capitol Street -- that was purchased by the Lerner Group – which owns the Washington Nationals – which proposes a 325, 000 square foot office building . To the south of L Street sits 1100 South Capitol Street that was purchased by Lawrence Rubin Corporation in August 2004 for $4.8 million. Geometry requirements would mean that the southernmost of these properties required to “steer” a tunnel alignment beneath South Capitol Street from the east in order to avoid St. Vincent DePaul Church in its existing location, would be the Lerner group property.

What evidence is there of any right of way reservation from the Lerner Group property and the Exxon gasoline station -- properties 4 and 6 above -- respectively at 1000 and 950 South Capitol Street?

Illustration from South Capitol Street Waterfront Vision

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