Hi there.

Shafts are essential to the building and functioning of all sorts of tunnels. All tunnel types may be accessed from the surface to the level of the tunnel thanks to them, including those used for underground rail tunnels and public transportation. The shaft is a long, thin, vertical cylinder that sits on the base and is articulated with fluting in certain orders (vertical grooves). The shaft may also gently curve inward such that the bottom is broader than the top.