Delhi Metro set for major expansion as Central Secretariat station to become new interchange hub | Details Delhi Metro's Central Secretariat station is set to transform into a major triple interchange hub with the upcoming Magenta Line extension under Phase 5A. The move aims to improve connectivity, cut travel time and reduce dependence on private vehicles in central Delhi. New Delhi:Delhi's metro network is gearing up for a transformative upgrade as the Central Secretariat station is set to become the capital's newest and most important triple interchange metro hub. Central Secretariat to emerge as a super interchangeAt present, Central Secretariat station serves as an interchange between the Yellow Line and the Violet Line. The Central Secretariat area houses several major government offices where thousands of people commute daily using cars and two-wheelers.