SFMTA Photographer Robert Pierce stands at the entrance of the Tunnel Portal, which will lower trains underground to the first station at Yerba Buena/Moscone Station.
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At 4th and Folsom, crews have dug out a trench and built a steel structure for the Yerba Buena/ Moscone Center Station.
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Crews continue welding and reinforcing the walls at the Yerba Buena/Moscone Station.
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In the SF Downtown core, crews have little excavators and big excavators to excavate the future Union Square/Market Street Station.
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This big excavator removes dirt out of the concourse level at the future Union Square/Market Street Station.
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This little excavator was used to create the northern concourse level of the Union Square/Market Street Station.
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At the Chinatown station, crews have already dug down to the mezzanine level and will continue to excavate to the tunnel level.
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Welder prepares for work in the trench of the future Chinatown Station.
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Crews prepare to drill into unexcavated dirt on the other side of the signature arch at Chinatown Station.
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Construction workers prepare the equipment needed for the Rocket Boomer, which will shoot a concrete and water mixture -- shotcrete -- through drilled holes to stabilize unexcavated dirt on the other side of the wall at the Chinatown Station
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The Rocket Boomer sprays shotcrete to stabilize the unexcavated dirt to increase safety for workers who will continue digging on the other side of the wall.
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The concrete and water mixture from the machine showers the equipment, leaving a puddle beside the signature arch at Chinatown Station.
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North of the main head house at Chinatown Station, crews are building the future emergency stairwell on Stockton Street.
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Crews installed the horizontal pillars after excavation to prevent the walls from caving in at Chinatown Station.
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MTC was invited to tour the construction of San Francisco's Municipal Transportation Agency's Central Subway project, a large-scale underground infrastructure project designed to extend the exising T-Third Light Rail north to Chinatown. Construction of this project began in 2013 and is expected to be completed by 2019. The Central Subway will speed up travel time north and south along the corridor and better connect neighborhoods to the retail, cultural and sporting centers of the city. Read more