How large is a tunnel boring machine?
In general, each of these machines are all custom made for each construction project and varies in size. They could be as small as 2 meters in diameter to more than 17 meters for the world’s largest machine. The length could be as long as 5 to 10-something meters for the boring machine itself, and 80 to 100 meters long if you include the entire facility to operate the machine. The lightest machine can weigh 30 tons or more.
Tunnel Boring Machine [THE GREAT PICTURE BOOK OF CONSTRUCTION EQUIPMENT]