Seite - 1546 - in Book of Full Papers - Symposium Hydro Engineering

7. COST ANALYSIS Following are the main factors affecting overall cost of the tunnel a)Capital investment b) Cost of equipments c) Interest charges on capital cost of tunnel, d) Annual maintenance charges, e) Whether lined or unlined and f) Cost of gates and their hoists. 8. TUNNEL INSPECTION AND MAINTENANCE Inspection of tunnel and its maintenance takes an important role in sustainable functioning of the tunnel. Inspection is carried out at lean water levels. Sometime tunnel has to be closed down. As such very little time is available for inspection as compared to other types of tunnels.Another hurdle for inspection of hydraulic tunnels is remoteness. Cavitations: - Design shall be such that negative pressures are avoided. Cavitation observed at Sardar Sarovar tunnel is shown in Figure 4. Figure 4. Prototype photograph showing exposed reinforcement inside Tunnel due to cavitations 1546