The Delhi Metro is a rapid transit system serving Delhi and its satellite cities of Gurgaon, Noida, Faridabad, Ghaziabad, Bahadurgarh and Ballabhgarh, in the National Capital Region of India. By far the largest and busiest metro in India, and second oldest after the Kolkata Metro it is the world's 8th longest metro system and 16th largest by ridership. The network consists of eight colour-coded regular lines, running 343 kilometres (213 mi) serving 250 stations. The system has a mix of underground, at-grade, and elevated stations using both broad-gauge and standard-gauge. Delhi Metro operates over 2,700 trips daily, starting at around 05:00 and ending at 23:30 hrs.