|Satellite + Paint|
On the satellite image to the right, I show the Capital Hill Tunnel that carries passenger trains to Union Station in blue and the Virginia Ave./Navy Yard Tunnel that helps bypass freight trains around Union Station in yellow.
Below, the signal on the passenger tracks near the south portal looks like B&O. Before the Chessie was formed in 1972, B&O and C&O had already merged in 1963. (The B&O Chicago Terminal and Western Maryland were added to B&O-C&O in 1972 to form the Chessie system. [Parks])
Having just left Washington Union Station, Chesapeake & Ohio E8A #4003 exits the tunnel beneath First Street in Washington, D.C. with train #1, the westbound "George Washington," on December 6, 1970. Roger Puta photo/Marty Bernard collection.
[Update: this is probably a different tunnel in Washington, DC.]
|Old Satellite, east portal|
|Old Satellite, west portal|
They are using two 48-foot movable forms to construct the tunnel lining. Rubber mats are used under the concrete ties and under the granite ballast to protect the concrete floor of the tunnel and to stop vibrations from bothering the neighbors "Project-related utility work has substantially reduced the potential for the existing tunnel to be flooded during heavy rain events." Rather than driving steel piles into the ground, the contractor is drilling holes that are filled with steel and concrete. This avoids disturbing the neighbors with the noise, vibrations and dust of pile driving.
[Trains Magazine, February, 2017, pp38-45]
I found a video of a pile driver that lets you hear the banging rather than replacing the audio with muse.
The new tunnel is built south of the existing tunnel. When it was completed in December, 2016, the track was shifted to it so that the old tunnel can be removed and replaced with a second tunnel. Then CSX can double track this stretch. The tunnels are being built with cut-and-fill. That means that at least parts of Virginia Avenue is unusable for years. Decades ago the subways in Washington DC were built with cut-and-fill, and I remember when I visited my aunt that she complained that it was really hard driving around town because so many streets were closed.
This tunnel will finish the 61 clearance projects that were needed for CSX's National Gateway project that supports running double-stack trains from east coast ports to the heart of the Midwest including their largest intermodal terminal in North Baltimore, OH.
Update: I noticed a Nov 2019 image has caught the construction in progress.