Photos: Central Subway making progress

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Please excuse their dust

By Brock Keeling@BrockKeeling May 5, 2017, 1:47pm PDT

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Looking north near the bottom of the tunnel portal ramp, concrete forms are in place prior to pouring the final track foundations, called plinths. — “Looking north near the bottom of the tunnel portal ramp, concrete forms are in place prior to pouring the final track foundations, called plinths.”

It’s coming along nicely, isn’t it? The 1.7-mile, $1.5 billion-plus Central Subway project is more than halfway done. And for residents who live any near the in-progress new line (e.g., your weary Curbed SF editor), the finish line cannot come soon enough.

The most recent batch of (gorgeous) photos, care of SFMTA photographer Robert Pierce, show what’s up underground as of mid-April. The interior skeleton of the subway is still under construction. The tunnels have developed more form. Lots of dust and dirt.

The Central Subway will feature four stations:

4th and Brannan Station at Fourth and Brannan (street level)
Yerba Buena/Moscone Station at Fourth and Folsom streets (subway)
Union Square/Market Street Station on Stockton at Union Square (subway)
Chinatown Station at Stockton and Washington streets (subway)

Completion date is scheduled for sometime in 2019. Here are some recent images.

“Bulldozer and excavator operators coordinate excavation operations inside the cross-cut cavern, where left side drift invert work for the south platform cavern has begun.”

“Workers loosen material inside the left side drift invert, which is then transferred by excavator to a waiting bulldozer for storage inside the headhouse before being brought to the surface.”

“Looking south up the tunnel portal ramp, workers have installed spacers to keep tracks aligned when concrete is poured for the final layer of the ramp invert.”

“A bulldozer makes runs between the right side drift of the south platform cavern and the collection area at the south end of the headhouse during excavation work.”

Workers excavate shallow trenches following rain inside the bottom of the headhouse, where a lattice of large grounding wire will be installed.<br> — “Workers excavate shallow trenches following rain inside the bottom of the headhouse, where a lattice of large grounding wire will be installed.”

The first layer of rebar to construct the northern half of the headhouse invert slab has been installed. When finished, the reinforced concrete slab will be over five feet thick. — “The first layer of rebar to construct the northern half of the headhouse invert slab has been installed. When finished, the reinforced concrete slab will be over five feet thick.”

Workers use air hoses to clean out debris in the recently-excavated invert of the left side drift in the north platform cavern.<br> — “Workers use air hoses to clean out debris in the recently-excavated invert of the left side drift in the north platform cavern.”

Vertical steel beams embedded in the exterior pile wall are prepared for welding small steel pegs as part of upcoming shotcrete reinforcing work. Steel mesh used to reinforce shotcrete will hang from these pegs, providing a solid connection to the wall st — “Vertical steel beams embedded in the exterior pile wall are prepared for welding small steel pegs as part of upcoming shotcrete reinforcing work. Steel mesh used to reinforce shotcrete will hang from these pegs, providing a solid connection to the wall structure.”

Rebar is cut away from pieces of concrete, which formerly reinforced the subway tunnel sections now being removed inside the station as part of station cavern excavation work. — “Rebar is cut away from pieces of concrete, which formerly reinforced the subway tunnel sections now being removed inside the station as part of station cavern excavation work.”

Looking toward the northeast corner of the headhouse, the north half of the invert slab's rebar cage has already begun to be assembled. — “Looking toward the northeast corner of the headhouse, the north half of the invert slab's rebar cage has already begun to be assembled.”

A crew clears out small trenches following rain inside the headhouse, where the massive lattice of copper grounding wire will be installed. — “A crew clears out small trenches following rain inside the headhouse, where the massive lattice of copper grounding wire will be installed.”

A crew cleans up a work area on the west slurry wall during rebar installation as part of headhouse invert construction. — “A crew cleans up a work area on the west slurry wall during rebar installation as part of headhouse invert construction.”

“A pedestrian walkway has been opened on the north side of Washington, reconnecting the sidewalk to Stockton from Powell.”

“A crew clears a portion of the work site along the north side of Washington between Trenton and Stockton to restore pedestrian access with construction of a temporary walkway.”

Central Subway photos: January 2017 [Curbed SF]
Central Subway photos: February 2017 [Curbed SF]
Central Subway Project [site]