Though it may not seem like the thing will ever be done, underground work on the Central Subway and its three subterranean stations is ongoing, and will be through next year. The SFMTA has employed a multimedia producer to document the process — and prove that there's a lot going on down there that we can't see — and his name is Robert J. Pierce. He talks to the Chronicle this week and explains that the reason we're seeing so little of the process is that the SFMTA "chose the cut-and-cover mode of construction to minimize impact on those using the streets above," in contrast to how BART was constructed in the 1960s and 70s with a huge trench dug all along Market Street (something that many credit with turning mid-Market into the seedy place it became, as businesses were decimated by the construction.

The three underground stations, where excavation work continues, are at Yerba Buena/Moscone Center along Fourth Street between Folsom and Hoawrd; Union Square/Market Street which will have entrances along Stockton at Ellis and at Geary; and Chinatown Station which is going on beneath Stockton and Washington Streets, between Jackson and Clay.

The entire tunnel has been dug, but as you can see in the video there's a lot of work happening before we see actual platforms and stations take shape. The footage was all shot on October 28, 2016.

Pierce tells the Chron that he feels like a kid getting to explore these underground construction sites, adding, "You go down there, and it's like being in some of underground cathedral. The sights, sounds, and smells are so unique, you can't really compare it to anything else."

The subway is expected to open for passengers in 2019, and will ultimately connect Chinatown to the T-Third line, to Sunnydale Avenue.

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