The trains run on 553 kilometers (344 mi) of electrified mainline railway owned by the Bane NOR.

The commuter rail operates mainly within Greater Oslo and two of the lines only provide services within the urban area.

Six of the lines span beyond the urban area, reaching the counties of Østfold, Hedmark, Oppland and Buskerud.

All other lines in the network are now called "Regionaltog" (regional trains) and they have 30 or 60 minutes between departures and often take an hour from Oslo to the end station.

Located in the central business district of Oslo, all lines either terminate at, or run through the station.

Along the West Corridor, the Drammen Line runs straight into the Oslo Tunnel, which starts directly beneath Oslo S. Trains run through Nationaltheatret, Norway's second-largest station, while in the tunnel.

[5] Spikkestad is 44 minutes[9] and 37 kilometers (23 mi) from Oslo S.[10] Lines R12 and R13 continue through the Lieråsen Tunnel and make two more stops (R13) before reaching Drammen.

[5] Årnes is 53 minutes[16] and 58 kilometers (36 mi) from Oslo S.[17] After Årnes, trains call at another station, Skarnes before reaching Kongsvinger Station,[5] which is 1 hour and 10 minutes,[16] and 100 kilometers (62 mi) from Oslo S.[17] Along the South Corridor, there is since end of 2022 a tunnel, Blix Tunnel for fast trains without any stops before Ski Station, which includes lines R21, R22 and R23.

The opening of this tunnel gave reason for a change in the Oslo regional and commuter rail systems.

Manned sections, with gray doors, have a conductor and allow passengers to purchase tickets.

[33] Class 69 is a series of 88 two and three-car electric multiple units built by Strømmens Værksted between 1970 and 1993.

A motor car has a power output of 1,188 kilowatts (1,593 hp), allowing a speed of 130 kilometers per hour (81 mph).

[35] Eighty-two units remain in service, although some of those are used on the Bergen Commuter Rail and the Arendal Line.

Each unit has a power output of 2,550 kilowatts (3,420 hp), allowing a top speed of 160 kilometers per hour (99 mph).

[37] The trains have better accessibility than Class 69 and unlike their predecessors are equipped with an electronic public information system.

Class 62 was a series of four multiple units built in 1931 and 1933 by Skabo Jernbanevognfabrikk and Norsk Elektrisk & Brown Boveri (NEBB).

The units had a power output of 344 kilowatts (461 hp), giving a top speed of 70 kilometers per hour (43 mph).

[41] The Class 65 motor cars had a power output of 464 kilowatts (622 hp) and a top speed of 70 kilometers per hour (43 mph).

This line, along with the section from Drammen to Kongsberg, were built with 1,067 mm (3 ft 6 in) narrow gauge and did not connect to the main station of Oslo Ø.

These proved not to be sufficiently powerful for the large traffic and were later moved to less used services from Oslo V to Asker or Heggedal.

[55] From 1936, NSB took delivery of Class 65 multiple units, replacing El 1 as the primary hauler on the electrified commuter rail network.

[56] The Østfold Line was upgraded to double track and put into service in four sections: from Bekkelaget to Ljan on 1 June 1924, from Oslo Ø to Bekkelaget on 15 May 1929, from Ljan to Kolbotn on 15 December 1936 and from Kolbotn to Ski on 14 May 1939.

Double track from Tøyen to Grefsen opened on 27 May 1962 and the sections from Jaren to Gjøvik was electrified in 1963.

They had a maximum speed of 130 kilometres per hour (81 mph); this had a significant cost impact, as it allowed not only faster travel time, but allowed the services from Oslo Ø to Lillestrøm and Ski to run fast enough to dispense with one third of the previous number of units.

[69] In 1997, NSB ordered 36 Class 72 multiple units to supplement and replace existing material.

[70] They were painted green and branded as part of the NSB Puls scheme, which was quickly abandoned.

The trains have a maximum speed of 200 kilometers per hour (120 mph) and a faster acceleration than the older classes.

It is a 22.5-kilometer (14.0 mi) long line, is built nearly entirely in a single tunnel, and will connect Oslo Central Station directly with Ski and will allow speeds at 200 kilometers per hour (120 mph).

It will allow higher speeds and capacity southwards for the lines to Moss and Rakkestad, as well as regional trains to Østfold and Sweden.

[80] At this time, December 2022, several of the local lines which went farther from Oslo and typically with departures once per hour, were redefined as regional trains and got a letter R instead of L in their name.