The Helsinki Regional Transport Authority (Finnish: Helsingin seudun liikenne, HSL; Swedish: Helsingforsregionens trafik, HRT) is the inter-municipal authority that maintains the public transportation network of the nine municipalities of Greater Helsinki, Finland. HSL oversees the operation of all of Helsinki's public transportation. The system consists of local buses, trams, metro trains, ferries, commuter trains, and bikeshare. Apart from four electric buses, HSL does not own rolling stock. Due to this, HSL relies on third-party contractors for the day-to-day operation of the transit system.