by Jessica Kwong
Following the lead of the first Central Subway tunnel-boring machine that drilled beneath Union Square late last year, the machine nicknamed Big Alma on Tuesday began making its way through the same undercrossing. To build about 425 feet of new tunnel under the existing Muni and BART infrastructure, Big Alma will turn slightly left beneath Fourth Street, just south of Market Street, and veer right to go north under Market and Stockton streets.…[ Read more ]