Line 7 has the longest underground section on the Tehran metro network and it is also the deepest, running up to 56m below street level.
Services are operated by a fleet of 20 eight-car trains.
When the remainder of the line opens in March 2018, Line 7 will be 31km long with 34 stations.
Together with Line 6, Line 7 will form a metro ring around the centre of Tehran.
Tehran Urban and Suburban Railway Company announced last June that the first section of Line 6 will open in September. The 35km line from Sulqan in the northwest to Dolat-Abad in the southeast will serve 27 new stations.
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