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. The two main sections, SRL East and SRL North, are planned to form a single 60 km (37 mi) fully automated orbital metro line through the city's middle suburbs, with 13 stations between Cheltenham and Melbourne Airport connecting to eight existing Melbourne rail lines across four sections: SRL East, SRL North, SRL Airport and SRL West.