This is a wikipedia page for a company in Germany that makes these huge Tunnel Boring Machines like the one that dug the tunnel connecting London and Paris, and the tunnel they put in Boston harbor. You could count these huge projects on one hand yet according to this page they have been involved in 2,600 projects! Not only so but it describes them as "a market leader" indicating there are other companies as well.
https://en.wikipedia.org/wiki/Herrenknecht
The company was established in 1975, 3 years after the US sent up Pioneer 10 to find Nibiru.
I found this on the website for Robbins, another Tunnel Boring Machine company located in the US
17 companies referred to as the "leading companies"
The key players contributing to the robust growth of the tunnel boring machine (TBM) market comprise CRCHI, Herrenknecht, CRTG, LNSS, Tianhe, Mitsubishi, Komatsu, Kawasaki, NHI, Terratec, IHI, Tianye Tolian, SELI, Xugong Kaigong, Hitachi Zosen, JIMT, and STEC. The leading companies are taking up partnerships, mergers and acquisitions, and joint ventures in order to boost the inorganic growth of the industry.
The Global Market for these machines is estimated at $5 billion
The global Tunnel Boring Machine (TBM) market was valued at $3779 million in 2017, and analysts predict the global market size will reach $5480 million by the end of 2028, growing at a CAGR of 3.44% between 2017 and 2028.
Let that sink in, these are simply the tools for digging the holes. On a construction project the parts are usually considered to be 1/3 the cost. A tool is generally not even factored in. Still, this suggests they are spending upwards of $15 billion a year digging tunnels.
With all these companies we might have 20,000 projects. If we guess that the 20 largest economies are responsible for 80% of these projects we are talking about 16,000 projects in 20 countries. Again, assume the US has more than other countries and we probably have 1,000 projects in the US! We may have heard of three or four of them, maybe if you are really tuned into the US construction industry you have heard of 10 of them.