New Delhi is a major junction in the Indian railway network and is the headquarters of the Northern Railway. The five main railway stations are New Delhi railway station, Old Delhi, Nizamuddin Railway Station, Anand Vihar Railway Terminal and Sarai Rohilla. The Delhi Metro, a mass rapid transit system built and operated by Delhi Metro Rail Corporation (DMRC), serves many parts of Delhi and the neighbouring cities Faridabad, Ghaziabad, Gurgaon and Noida. As of December 2016, the metro consists of six operational lines with a total length of  and 160 stations. Several other lines are under construction and expected to be commissioned in 2017 adding another 150 km length. It carries almost three million passengers every day. In addition to the Delhi Metro, a suburban railway, the Delhi Suburban Railway exists.