How many tunnel boring machines are working in the US?

As of October 2023, there are approximately 30 to 40 tunnel boring machines (TBMs) actively working on various projects across the United States. These machines are primarily utilized for infrastructure projects, including subway systems, water supply tunnels, and utility installations. The exact number can fluctuate based on ongoing projects and new initiatives. For the most current information, it's best to refer to specific project updates or industry reports.