tunnels are bored depending on the soil, length, diameter. Most projects I have seen use TBMs and the New Austrian Tunneling Method. Explosives are quite the minority (not many tunnels are in solid rock), even the Gotthard tunnels were dug with TBMs
tunnels are bored depending on the soil, length, diameter. Most projects I have seen use TBMs and the New Austrian Tunneling Method. Explosives are quite the minority (not many tunnels are in solid rock), even the Gotthard tunnels were dug with TBMs