Buses in Helsinki
Local and regional bus services are a large part of public transport in the Helsinki region. HSL bus services include internal services in Helsinki, Espoo, Kauniainen, Vantaa, Kerava, Kirkkonummi, Sipoo, Siuntio and Tuusula and regional services between them. Since 2010, the planning and timetabling of these bus routes have been done by Helsinki Region Transport, an organisation to which the aforementioned municipalities belong. Prior to HSL's inception, Helsinki's internal lines were the responsibility of Helsinki City Transport, with all other bus services being organised by YTV, HSL's predecessor. Principles of line numbering Bus lines running solely inside the municipality of Helsinki have two-digit numbers, except for lines 52 and 53, which extend into Espoo, as well as trunk line 30 and night line 95N, both of which extend into Vantaa. Three-digit numbers are used by all other lines, (except for Helsinki internal lines 500, 506, 611B and 831(K), as well as part of Helsinki's minibus routes). Some lines have a letter or two at the end of their number, for example 611B. This denotes that the line differs from the main route in some way. For example, the route of line 611B is shorter than that of line 611. These