What an awesome writeup. Just wanted to add a link to a good website tracking the progress of the Hampton Roads Bridge Tunnel expansion project, something near and dear to me as someone who has suffered much frustration driving through the current one. The three bridge tunnels around HR themselves are pretty cool engineering feats. I found the explainers at this website about the TBM in use quite interesting.

- the main project site: https://hrbtexpansion.org/

- TBM page: https://hrbtexpansion.org/tunnel-boring/

I can no longer find the exact page there that has the details of the TBM but these are pretty close:

- good slide with diagram: https://www.virginiadot.org/VDOT/Business/asset_upload_file1...

- some cool stuff but lots of broken links: http://www.virginiaplaces.org/transportation/hrbt.html