Topic: flood control

Emergence of Tunnel Boring Technology Tunnel boring machines (TBMs) first emerged in the mid-nineteenth century as engineers sought efficient ways to excavate longer tunnels with less manual labor. One of the earliest successful TBMs was developed in 1887 for construction of the Boston subway tunnels. Powered by compressed air and equipped with a rotating cutter head, it could excavate rock and soil at a rate five times faster than traditional drill-and-blast methods. Throughout the early twe...