Sure is! Those are the first couple of gantries that make up the TBM, they house all the ancillary equipment like electrical cabinets, ventilation boosters, hydraulic pumps, etc.
And that star-shaped thing at the front of the shaft isn't part of the TBM unfortunately, that would be part of the...
Looks like work has officially begun on the launch shaft!
https://www.linkedin.com/posts/north-end-connectors-nec_northendconnectors-nec-yongenorthsubwayextension-activity-7394099995651538945-6rsf?utm_source=share&utm_medium=member_desktop&rcm=ACoAADWJa6MBAZKL-GaYC8sFEQ6H1RVHBql-1T8
Likely not. Maybe a couple portions of the shield will be assembled prior to delivery to the site but most will remain as they were unloaded from the ship (including the cutterhead as seen in the photo)