There are three lines in the Gothenburg commuter rail system. The first line opened in 1960, to Alingsås. In 1992 another line to Kungsbacka was opened, when the railway had been rebuilt as double track. The railway to Trollhättan was being rebuilt as a double track railway and completed in 2012, with both a third commuter rail connection to Älvängen and a denser regional schedule to Trollhättan introduced.
In opposite to Stockholm, Västtrafik allow their monthly tickets (of course within the geographic area the ticket covers) to be used also on SJ inter-city trains (but not X_2000 and some other fast trains). From 2010 all Västtrafik regional trains are part of the Västtrafik pay-per-ride ticket system.
The regional trains to Borås, Vänersborg and Skövde go in addition to the long-distance trains, filling up gaps between them, to create one-hour schedule. The trains to Strömstad are kind of long-distance train by themselves, but the county authorities has responsibility, since it was inside one county also before the county reform 1998. The railways to Borås and Strömstad are single track, which makes it hard to have denser schedule than once per hour, without having too many slow train meetings, and there are freight trains as well. The Gothenburg-Stenungsund line has extra departures creating half-hour schedule in rush hour. To Vänersborg there is from 2012 double track and sometimes two trains per hour.
A fifth rail line that can be counted as a regional rail line is the ÖresundstågGothenburg-Malmö-Copenhagen (360 km). Västtrafik monthly passes are valid to Kungsbacka, but this is not usually considered a Västtrafik line.
The most used connection on these lines is the connection to Borås, if including the about 60 daily buses that go since the railway can't support the demand. There are plans to build a new railway here, as part pf Götalandsbanan, which is going to be a super-highspeed railway (max 320 km/h). The first part, Mölnlycke-Bollebygd, is planned to be opened around 2020-2025, and later extended to Stockholm.