How metro passes the muck down under

The Delhi Metro’s newly constructed underground tracks are first used by special ‘muck trains’ before passenger trains. These battery-operated trains collect the excavated sludge from the tunnel boring machines (TBMs) using a conveyor belt connected to the cutter head of the TBMs. Each muck train can carry around 70 cubic metres of muck, which is then transported to a muck pit at the end of the tunnel. The muck is later transported to low-lying areas. The underground work for the Delhi Metro’s Phase IV expansion is expected to be completed by 2025.