Does anybody know why the Japanese changed the number from 250 meters (820 feet) to 180?

section 2.3.1.2:
“February 1999, the San Francisco Board of Supervisors passed a resolution repealing its prior
endorsement of the Main/Beale site for a new terminal”…
“AC Transit supported this action noting that the Main/Beale site would
not provide the level of transit service that could be provided at the current terminal”…
“Withdrawal of the Main/Beal site was also consistent with the provisions of Proposition H,
which calls for a multi-modal facility at the current Transbay Terminal site.”

so basically nothing technical there, just politics and a bus operator.

I’ll also note that while prop H requires transbay to be constructed at the same site, it does not say the train station has to be in the basement.
It also states “yield the highest possible transit use by residents and commuters”, which is being ignored in a number of ways (no concern for passenger flow, no concern for operational flexibility, no concern for tunnel approach constraints, tight curves causing slower train speeds)

section 2.3.2.3:
“The alignments along Beale Street leading from The Embarcadero would pass near the Bay
Bridge anchorage, raising issues regarding the effects of cut-and-cover construction on this
major structure.”…
“The Caltrain terminal at Market and Beale Streets was ultimately withdrawn from further
consideration because of the narrow right-of-way available on Beale Street, requiring
construction of a multi-level train station between two historic structures.”

So “raising issues”. Exactly why further study is needed, I saw nothing saying these issues were determined to be insurmountable. There’s lots of space between main and Beale where the tunnel could run, but they only considered the option that puts it directly next to the Bay Bridge anchorage.

The second section says a multi-level train station would be required, but that’s only true if you only allow the trains to be completely under Beale street. There’s plenty of open space between Beale & Main that could allow for a wide & shallow train station.

Which is why they are going to build a tunnel from Oakland to San Francisco someday. Not only do people want to get from San Francisco from Los Angeles they want to get to San Francisco from Sacramento… and Cloverdale and Calistoga and Fairfield and Stockton and …. Of course if there is no place to put a station in San Francisco building a tunnel would be pointless.

They can build tall buildings on the land between Main and Beale or they can build a train station and then build tall buildings over the station. I’m sure someplace in you urban planning courses they mentioned that Grand Central was financed that way. Or that the reason the original Penn Station was torn down was to make way for Madison Square Garden and tall office buildings or took you for a virtual tour of the train stations in Tokyo that have malls and office complexes over them or …..

Where is your evidence? Can you cite anything to contradict those EIRs? I am genuinely interested.

A CHSRA responsibility is to design a system enabling 5-minute separation of trains. I don’t see it yet.

I am pretty certain it is accurate; however, with so many folks here apparently knowledgable of such things and have likely already examined such… I’d be interested to learn what they see before I crunch some numbers.

To second one, I didn’t ask why to build now rather than later, I asked why to spend the money on something that can’t be used for a decade (and has been poorly thought out) rather than improvements that will provide benefits as soon as they are complete (like grade separations).