https://youtu.be/btVyY0__elk?si=auBqrDSHFVLk3HL0
Worse yet, the newly released CHSR report states all new tunnels will initially be built as single track tunnels because the initial operating segment will operate as a single track line with passing sidings. They are single tracking the line to save enough cash to get something built sooner.
The double tracking and second tunnel will be built much, much later.
At the rate they are building CHSR, by the time they get to double tracking the line,, they will have to replace the original tracks.