When the world’s largest drilling machine smashed through a 5-foot-thick concrete barrier, emerging in a cloud of dust from an earthen hole that will become one of the world’s biggest vehicle tunnels, a smattering of cheers floated down from the workers and officials on an observation platform above. One tunnel worker climbed up the machine’s massive drill head and waved a U.S. flag.

But as historic moments go, it wasn’t much of a celebration.