Monday, April 19, 2010

Planning in a Vacuum- CSX-SE Freeway Tunnelization

With Virginia Avenue to be torn up anyway, what about something more comprehensive?

How will the CSX tunnel expansion project affect a future tunnel project to replace the existing elevated SW-SE Freeway?

Proximity Demand Coordination- yet were where the Feds?

Why was this corridor’s planning languishing as EYA and others rushed in to develop up against the right of way?

Note the close proximity of the SE Freeway’s transition from elevated berm to open viaduct in order to cross the mouth of the Virginia Avenue Tunnel, with the connections at left with the interchange with the Center Leg and the SW Freeway.

Note how the viaduct portion over South Capitol and New Jersey Streets is entirely south of the CSX railroad, before swinging to the railroad’s north side at 1st Street SE

That was how the original 1955 Inner Loop design had it, shown here with the original East Leg along 11th Street.

This 1961 rendering below at its top shows an un-adopted routing of the SE Freeway, along the Virginia Avenue railroad tunnel’s southern side. I have not yet seen a rendering of this option for the segment further east (with this rendering failing to show even the connections to the 11th Street Bridges[s]).

Given their proximity and grade requirements – freeways can tolerate 5-7 % while heavy rail can only take 1% -- and the short distances to the 11th Street Bridges – the under-grounding of the SE Freeway is surely a project to coordinate with that for reconstructing the railway, such as that now announced to start construction by 2011.

Here’s a close of the 1955 design.

Here’s what was built.

And here’s a close up where the freeway crosses the RR at the start of the latter’s tunnel

Note the proximity of the support columns for the SE Freeway viaduct.

Photos by Matt Johnson

The CSX Project:

Reconstruct the Virginia Avenue railroad tunnel with greater height and width; digging it lower and widening it with a temporary trench to the south that is later filled in.


- Dig a trench about 25 feet wide along the existing tunnel’s southern side for diverting the trains throughout the reconstruction
- Remove the roof and at least one of the lateral walls, excavate the floor 3 or 4 feet lower and widen to 40 feet.
- Route trains into reconstructed tunnel and fill the trench

Not yet known to me is:

- whether or not both of the existing tunnel walls are replaced/relocated
- whether the center-line shall remain the same, or is shifted
- the method of construction, particularly the method of securing the ‘temporary’ trench- perhaps a less expensive yet noisier to construct pile driving instead of a more expensive yet quieter to build and more permanent slurry wall?


Facilitate the reconstruction-restoration of Virginia Avenue with a well thought overall plan encompassing the CSX project and a future underground SE Freeway

According to this communiqué from Capitol Hill:

- The District comprehensive plan stipulates that the railroad tunnel expansion should only occur in conjunction with the tunnelization of the existing parallel SE Freeway

Since this segment of the SE Freeway is an elevated berm-way, framed by vertical concrete retaining walls, its burial will require some space, particularly while maintaining traffic to and from the reconstructed 11th Street Bridges and the SW Freeway.

Apparently CSX shall pursue this tunnel augmentation project as inexpensively as possible, meaning:

- open trench construction (without a street deck), except for the cross streets
- replacing only one of the existing tunnel’s lateral walls, which given that era’s generous ‘over-engineering’ could be incorporated into the reconstructed tunnel, hence shifting the mainline fully to one side or the other.

With the ‘temporary’ trench to the south and the option of replacing one or both of the existing tunnel walls, the likeliest option is that of shifting the center-line to the north, closer to the elevated SE Freeway, using the existing southern RR tunnel wall to segregate the trench from the RR tunnel construction.

But given the cost premium of underground construction particularly with excavation, is simply configuring this project via filling in this space really its most cost effective and productive potential use?

What consideration has been given to any sort of coordination between the future stated goal of an under grounded SE Freeway tunnel from South Capitol Street to 8th Street with the CSX project?

Likewise, what about that concerning the just started 11th Street Bridges Project?

Let alone the accompanying mandatory project to so bury the SW Freeway, given that its meeting with the SE Freeway is an elevated viaduct, meaning that any CSX-SE Freeway Tunnel project would otherwise require its SE Freeway Tunnel be built while retaining the existing elevated berm-way SE Freeway until the realization of the full SW-SE Freeway Tunnelization Project. Clearly thus they must be planned all together, yet where’s any indication of that?

Photo by Matt Johnson
SE Freeway berm-way at left

Instead we have a situation with questionable decisions to extend new real estate development – aka buildings full of peoples’ dwellings – in extra close proximity to such major transportation corridors. The plethora of simply bad decisions as:

- Failing to reserve a strip of the Cappersburg properties along the along the area closest to the Virginia Avenue RR tunnel

- Failing to reserve a strip of the properties along the entire southern side of the SW Freeway, especially between 9th and 7th Streets with the 1999 construction of the ‘Capital Square’ townhouse project.

- Approving the ‘Capital Square’ project with its northernmost row of 28 townhouses- complication the future under-grounding of the SW Freeway via creating a right of way band pinch.

- Selling the interchange land for the northbound I-395 Tunnel on ramp between Massachusetts Avenue and K Street for the demolition special "Golden Rule" apartment house, blocking the on-rap and potentially creating a dangerous migratory pattern of elderly citizens carrying home their groceries from the nearest food market - also named 'Golden Rule' for the association with the Bibleway Church at the northern end of I-395.

- Allowing the transportation corridor reconstruction to lag behind decisions by entities as EYA to construct new dwellings

It is hardly a flattering indication of those within the government.

Given this track record, anyone is going to have to ask if the CSX project, in its current form, present the most optimal ‘defragging’ of this right of way- or might its cost savings as so configured, be more than offset by it increasing the costs of the SE Freeway Tunnel project?

SE Freeway Physical Realities:

Burying the SE Freeway is going to require some space, particularly with the need to maintain traffic throughout the construction to and from the reconstructed 11th Street Bridges.

Along its southern side is Virginia Avenue, with the RR tunnel beneath.

It has underpasses for cross streets.

It connects to its west to the SW Freeway, with the configuration being an elevated viaduct before a slightly depressed segment between 7th and 9th Streets Sw

It connects to its east with the 11th Street Bridges with a brief continuation to a set of tunnels beneath Barney Circle where it is truncated since 1974.

Situate the CSX Project to facilitate SE Freeway under-grounding, while preserving the easements for its connections to an under grounded SW Freeway, the already underground Center Leg and a future South Capitol Street Tunnel.

This is essentially ‘defragging’ the existing corridor right of way by assembling the needed contiguous space for constructing the future eastbound cut and cover SE Freeway tunnel before demolishing the existing elevated freeway to construct the westbound twin.

Such a stage ability is required to reduce construction impacts, and is subverted by the government’s apparent inability to just say no to developer projects located closer and closer to a right of way (such as the infamously placed row of EYA Capitol Square townhouses alongside the SW Freeway).

Basic options include:

- Cut and cover CSX tunnel shifted south, re-using existing northern tunnel wall, creating space for future eastbound cut and cover SE Freeway tunnel

- Cut and cover CSX tunnel shifted north, re-using existing southern tunnel wall, and thereby in the median space for future cut and cover SE Freeway tunnel

- Drilled railroad tunnel directly beneath eastbound lanes of SE Freeway berm, allowing full Virginia Avenue right of way for the future eastbound SE Freeway Tunnel

- Full Virginia Avenue right of way cut and cover tunnel accommodating the expanded railway and future eastbound SE Freeway tunnel

These decisions can’t be avoided.

Capitol Hill communities will need to be vigilant, including being fully willing to sue the government for failing to plan.

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