[rohit2412]

Why is it so unrealistic? For example, this line in Mumbai metro ( https://en.m.wikipedia.org/wiki/Line_3_(Mumbai_Metro) ), with 34 km of big tunnels and 27 stations is supposed to cost 3.4 billion. Surely, Chicago's 25-30 km line with just two stations (one sort of half built already) and smaller tunnels won't cost so much.

[jandrese]

Two things. 1 is that they're planning to use a lot of cut and cover which is a lot cheaper but more disruptive. 2 is that the project isn't complete yet so those final cost figures are still fiction.

[rohit2412]

No, only the stations are cut and cover. They have ordered 17 tbm for the tunnels.

About the cost estimate, I don't have any other completely underground metro line in a developing country to compare. But Is it the labor costs in developed countries?