Shafts are vertical wells or passages reaching from the ground surface down to the tunnel roof.

SHAPE:

The shafts may be rectangular or circular in shape. The rectangular shape may be adopted for temporary shafts which are to be filled up after the construction of tunnel is completed. The permanent shafts are to be lined with pressed steel liner plates orconcrete.

SIZE:

The size of shaft is to be decided by considering various factors such as quantity of much to be handled, size of muck car, etc.

LOCATION:

The shaft is located at such a place where depth would be minimum. Thus the ideal site for shafts would be valley and if there are chances for water to be accumulated in valley, arrangement should be made to prevent the entry of water in valley and to divert such water.

The majority of shafts are located directly over the centre line of the tunnel.It has the advantage of hoisting out the materials easily from the tunnel.

To construct shafts in rocks, the operations consists of Drilling, Blasting and Mucking. The method of excavation conforms to that of tunnelling in hard rock.