Dont know from where the figure of 8043Cr for Tunnel came.
EstimatedCost in Final Feasibility Report put out by BBMP:
18Km Hebbal-CentralSilkBoard Tunnel-Rs.15000Cr
28Km KR Puram-Nayandahalli Tunnel-Rs.25000Cr
Others-14964Cr
TOTAL-54964Cr
Most likely to double by completion time