The 1.7-mile, $1.5 billion-plus Central Subway project is reportedly 65 percent done and ahead of schedule, according to CBS SF, who note that the expensive expansion of the city’s light T Third Street Muni line is operating 12 hours a day, six days a week.

Most of that labor would remain hidden from the curious eyes of the public if not for the work of SFMTA photographer Robert Pierce, who began shooting the subway project six years ago.

In January, Pierce told Curbed SF that he was working to upload a backlog of dramatic new photos to the Central Subway Flickr account, and sure enough in the weeks that followed new images poured in, many of them focusing on labor around and beneath the incoming Chinatown station at Stockton and Washington.

Pierce, originally from Oregon, moved to the Tenderloin during the original dot-com boom. He’s also created several timelapse videos of the subway work.