The Proastiakos (; "suburban") is Greece's Commuter rail service, run by Hellenic Train, on rail infrastructure owned by the Hellenic Railways Organisation (OSE) (lines) and GAIAOSE (buildings and Trains). These services connect a participating city's central railway station to important locations such as a city's port or airport, as well as its suburbs and occasionally nearby towns and cities. As of September 2020, there are three Proastiakos networks serving the country's three largest cities: Athens, Thessaloniki, and Patras, providing them with commuter rail links towards their suburbs and also with regional services to other cities and towns. In 2016, the three systems carried 10.1 million passengers. As of 8 January 2017, the lines between the central stations of Athens and Halkida have been electrified, allowing EMU train service. The lines have been changed, making Athens's central station the main layover station. Those lines are Athens – ATH, Athens – Kiato, Athens – Chalcis. In Thessaloniki, there are two Proastiakos services. The first connects the city's New Railway Station with the cities of Katerini and Larissa, and the second links the city with Edessa. In July 2010, a new commuter rail service was launched in Patras, connecting the city with Rio. Photography and videography are permitted across the entire Proastiakos network; however, security personnel may often prohibit camera usage. History Proastiakos of Athens consists of 6 routes: The concept of regular and frequent suburban and commuter rail services was introduced in Greece in the 1990s. It became possible due to extra capacity becoming available through improvements to the existing lines and the construction of new ones. In the past, suburban services ran on very infrequent timetables and were not very popular. The construction of a new rail line between central Athens, its eastern suburbs, and the new Athens International Airport was decided in 1992–1993. During the construction of Attiki Odos motorway in the late 1990s, space was left between the main carriageways for the railway line. After two years of construction, the line to Athens International Airport opened in 2004. The first suburban services between Athens and the Airport were inaugurated using Stadler GTW and Siemens Desiro DMU trains. On 27 September 2005, the new standard gauge rail line reached Corinth, terminating at a new station, located at Examilia. This line today is served by "Proastiakos" suburban services, while initially "Proastiakos" trains stopped at Nea Peramos, Megara, Kinetta, and Agioi Theodoroi.