Wikipedia
The Proastiakos (, ) is the collective name for Greece's suburban ( commuter rail) services, which are run by TrainOSE, the country's only rail operator, on infrastructure owned by the Hellenic Railways Organisation (OSE).
As of March 2016 there are three Proastiakos networks, servicing 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 Athens, the Proastiakos offers a direct connection between Athens International Airport and Kiato, in the Peloponnese. The service also connects the port of Piraeus with Halkida in Evia, through Athens Railway Station, which is more commonly called Stathmos Larisis.
In Thessaloniki, there are two Proastiakos services. The first connects the city's New Railway Station with the city of 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 video-taking is permitted across the whole Proastiakos network, however very often the security personnel might create problems to photographers.