The original idea was to please a Chinatown power broker unhappy at the prospect of losing the Embarcadero Freeway. The plan was to give her a subway to Chinatown. Unfortunately things didn't work out. Here is an overview of what went wrong.
For starters the project was too costly. Way too costly. In fact at $1.58 billion for a mile of subway and a half mile of surface line, the Central Subway, if actually built, would become one of the most absurdly over-priced short stretches of rail line in the entire world.
It gets worse.
For most riders, the perceived Central Subway trip times, including the time required to walk to the station, descend to the train platform, wait for a light rail vehicle, travel to one’s stop and assend to the surface, would be longer via the Subway than via today’s buses.
And then there's the fact that because the subway is so deep there would be no stop or near at Market Street.
Transfers to no less than 25 east-west Muni lines would be longer and more difficult from the subway than from the buses now operating on Stockton Street.
No one living much north of Jackson Street would derive any benefit whatsoever from the subway.
Service on today’s T-Line is slow and infrequent. Service on the subway extension would never be any better than on the rest of the line.
And finally, the subway construction program and speculative development sure to follow would almost certainly destroy many small Stockton Street businesses, including the vibrant Stockton Street Produce Market.