Tehran Metro Line 1, coloured red on system maps, runs north–south and is 86.9 kilometers (54.0 mi) of which 14.9 km (9.3 mi) is underground (from Tajrish station to Shush Station) and the rest at grade (at surface level). The number of stations along the main line is 29 of which 22 stations are underground and seven above. The Airport branch has another three stations, all at grade. As of 2005, the line's total capacity is 650,000 passengers per day and trains make a scheduled stop of 20 seconds per station. The trains are made up of seven wagons, giving a nominal capacity of 1,300 seated and standing passengers. The maximum speed of the trains is 80 km/h (50 mph) per hour, in practice tempered to an average 45 km/h (28 mph) due to station stops, but 120 km/h (75 mph) on the Airport branch, so travel time for the 49 km (30 mi) from Shahed - Bagher Shahr Metro Station (short Shahed station) to Parand is just 34 minutes.
Line 1 runs mostly north–south, and from Shahed station has interchange platforms for its extension, sometimes in between termed as Metro Line 8, to Imam Khomeini International Airport completed in August 2017 and extended to Parand in December 2023.
