The Suburban Rail Loop (SRL) is a rapid transit system currently under construction in Melbourne, the capital of Victoria and second largest city of Australia. The system is divided into four distinct sections : SRL East, SRL North, SRL Airport and SRL West. The two main sections, SRL East and SRL North, are designed to form a single 60 km (37 mi) fully automated underground orbital metro line through the city's densely populated middle suburbs, with 13 stations between Cheltenham and Melbourne Airport connecting eight existing Melbourne rail lines and three major university campuses.