The document discusses the New Austrian Tunnelling Method (NATM) and tunnel lighting. NATM involves using the tunnel lining to support loosened rock, prevent water percolation, and give tunnels their shape while withstanding soil pressures. Tunnel lighting is needed during and after construction, with electric lighting now being preferred over older methods like oil and gas lamps. Electric lighting provides steady, bright light without consuming oxygen or producing gases.

5. New
Austrian
Tunnelling
Method
(NATM)

7.  Saves rock from air slake
 For water tunnels, lining gives smooth surface
reducing turbulence.
 Adds to the structural strength.
 Gives correct Shape to tunnel.
 Withstands soil pressures in soft soils.
 Supports loosened rock pieces during blasting.
 Prevents water percolation.

12. Tunnel Lighting
 Tunnels require lighting while construction and also
after construction.
 A light intensity of 260 lumens is said to be
satisfactory.
 For lighting Oils, Coals, Acetylene gas were used
formerly, but nowadays electric lighting is most
preferred.

13. Need of Lighting  Operation and Equipments Station
 Switches, turnouts and passing tracks
 Drilling and Mucking Zones
 On Drill Carriages
 Underground material supply and storage points
 At all obstructions
 Complete lighting after construction for utility of
vehicles, etc.

14. Electric Lighting  It is most commonly used for lighting in
tunnels and also is a most perfect source.
Advantages:
 Furnish Steady and bright light
 Does not consume oxygen
 No offensive gases are given off
 Easy for wiring and extension
 Lamps may be easily adjusted for intensity
desired.