superelevation
Active Member
Honestly I didn't know they staggered the launches like they do for twin tunnel boring machines.
Also, I really hope they put a map of progress in the website, it'll make for a good visual aid.
I thought they did both TBM At the same time as the pit area was empty in June when I last saw it. There was 2 TBM in various stages being built when I had my first look at the site.
It common to open things up in phases to get something up and running ASP when its a long and stage from day one.
Very common practice, with tunneling you are going in blind (even with drilling to test soil you can get unexpected stuff) so they stagger so they can more easily do the second tunnel. Its not uncommon to do a "pilot" tunnel on larger projects as was seen on the chunnel and Metro Construciton in Italy where a smaller tunnel is built first to make constructing the larger one easier.