The history of the Oslo Tramway and Oslo Metro in Oslo (Kristiania until 1925), Norway, starts in 1875, when Kristiania Sporveisselskab (KSS) opened two horsecar lines through the city centre. In 1894, Kristiania Elektriske Sporvei (KES) built the first electric street tramways, which ran west from the city centre. Within six years, all tramways were electric. The city council established Kristiania Kommunale Sporveie (KKS) in 1899, which built three lines before it was sold to KSS six years later. Both KSS and KES were taken over by the municipality in 1924, becoming Oslo Sporveier. The company gradually expanded the city tram network, which reached its peak length in 1939.

The Holmenkollen Line was the first light rail line, which opened in 1898 and ran west of the city. Later light rail lines in the west were the Røa Line (opened in 1912), the Lilleaker Line (1919), the Sognsvann Line (1934) and the Kolsås Line (1942). From 1928, they ran to the city centre via the Common Tunnel. East of the city, the Ekeberg Line opened in 1917, followed by the Østensjø Line (opened in 1926) and the Lambertseter Line (1957). The light rail lines were built by three private companies, Holmenkolbanen, Ekebergbanen and Bærumsbanen. By 1975, all had been bought by Oslo Sporveier.

The Oslo Metro opened in 1966, consisting of a line through the Common Tunnel to Jernbanetorget and the upgraded Lambertseter light rail line. The same year the Grorud Line opened. The next year the Østensjø Line was connected, and in 1970 the Furuset Line opened. The city council decided to close the tramways in 1960, and several lines were closed until the decision was revoked in 1977. In 1987, the Common Tunnel was completed. From 1993, the western lines were upgraded and connected to the Metro, allowing Metro trains to run through the city centre. The Metro's Ring Line was completed in 2006.

Street trams

Horsecars

The first attempt to introduce horsecar operations in Oslo (at the time called Christiania) were in 1868, when the engineer Jens Theodor Pauldan Vogt and the architect Paul Due applied for a concession. The application was rejected because the city council felt that the streets were too narrow. They made a second application in April 1874, and this time permission was granted. On 26 August 1874, Vogt and Due established Christiania Sporveisselskab ("Christiania Tramway Company"). Twenty-two long cars were delivered from the United States manufacturer John Stephenson Company, arriving in Christiania on 31 August 1875. The official opening took place on 6 October 1875. In 1879, the city and company changed the spelling of the name "Christiania" to "Kristiania".

The system initially had four standard gauge, single tracked lines, which had passing loops to allow trams to pass. Three originated at Stortorvet: the Gamlebyen Line, running east to Gamlebyen (now Old Oslo, but then called just Oslo); the Vestbanen Line, which ran west to Vestbanen station (Oslo West station); and the Ullevål Hageby Line, which ran west to Homansbyen, where the depot was located. In addition, there was a short connecting line between the Ullevål Hageby Line and the Vestbanen Line, but it was closed on 19 October 1875. The two lines that connected to the station only ran services that corresponded with train arrivals and departures; the other two lines had fixed fifteen-minute headway—decreasing to ten minutes from 22 June 1876. During the winter of 1875 and 1876, the company attempted to use sleds instead of wagons. They took delivery of seventeen units, but these were not as suitable as the wagons and the company instead chose to salt the rail tracks.

Profits were made immediately, and in 1877 an additional seven cars were delivered. The following year, a new line from Stortorvet to Grünerløkka was built—the start of the Grünerløkka–Torshov Line—along with a new depot. The Gamlebyen Line was extended to St Halvards plass on 2 December 1878, the Grünerløkka Line to Thorvald Meyers gate on 12 April 1879 and the Vestbanen Line to Munkedamsveien on 5 May 1879. The following year, the lines were merged to two through services: Homansbyen–Oslo and Vestbanen–Grünerløkka. After this, the company concentrated its investments into rebuilding the system to double track. Between 1887 and 1892, the company took delivery of 14 additional cars from Skabo Jernbanevognfabrikk, the same length as the Stephenson cars. The last horsecar delivery was 15 cars from Falkenried in 1897, which were designed so they could be converted to electric tram trailers. They were long and remained in service until 1939. In 1880, Kristiania Sporveisselskab registered a ridership of 1,499,000 passengers.

Electrification

The horsecar system was more expensive to operate than electric trams, and Christiania (later Kristiania) Elektriske Sporvei ("Kristiania Electric Tramway") was founded to establish an electric tram service. The initiative came from the engineers H. E. Heyerdahl, A. Fenger-Krog and consul L. Samson. KSS immediately attempted to buy the company, but the purchase failed. On 2 March 1894, the Briskeby Line opened, which ran westwards from the Østbanen station (Oslo East station) via the city centre and Briskeby to Majorstuen, using a 600 volt supply. At the same time, a branch line opened from the Briskeby Line at Slottsparken, heading further west to Skillebekk. At first a shuttle service was provided on the branch line, but by April a through service was offered to Østbanen station. The branch line was extended to Nobels gate on 31 December 1894, to Thune in 1901 and to Skøyen station on 21 June 1903 and is now known as the Skøyen Line.

The last street line built by KES was the Frogner Line, which opened in 1902 from Solli plass on the Skøyen Line to Frogner plass. It was extended to Majorstuen, where the depot was located, on 15 May 1914. From 1909, KES introduced numbered services, with the Briskeby Line numbered 1, the Frogner Line numbered 2 and the Skøyen Line numbered 3. KES bought 78 motorized cars and 66 unmotorized trailers; of which 20 cars were later rebuilt to trailers. The main manufacturers were Herbrand, Falkenried and Skabo, who delivering a continual stream of stock to the company until 1914. From then until 1925, there was sufficient rolling stock that only ten more vehicles were delivered.

KSS decided to convert its lines to electric traction as well. The first electric trams ran on 29 September 1899, and the conversion was completed by 15 January 1900. At the time of electrification, KSS had 57 horsecars; 38 of these were later converted to trailers, while 19 were decommissioned. The John Stephenson and Skabo trailers were taken out of service in 1917–18, and sixteen of these were sold to the Bergen Tramway and Trondheim Tramway—the latter rebuilding them to meter gauge. One of the original Stephenson cars has been preserved at the Oslo Tramway Museum.

The Vestbanen Line was extended west from Vestbanen station towards Skillebekk in two stages, on 21 December 1898 and again on 23 June 1899. The Gamlebyen Line was extended further east on 17 November 1899 to Oslo Hospital. The Vålerenga Line, which ran east from the city centre, opened on 3 May 1900, and the Kampen Line, which ran parallel but further north, on 6 June 1900. The first street line out of Kristiania into Aker was opened in three stages as an extension of the Grünerløkka–Torshov Line: on 29 September 1899 to Torshov, on 2 October 1901 to Sandaker and, finally, to Grefsen Station on 28 November 1902. For the electrification, KSS ordered 47 new trams from Falkenried and Waggonfabrik Linke-Hoffmann; these remained in service until 1967. In 1900, the tramway had a ridership of almost 17 million passengers, or 75 trips per inhabitant.

First municipal trams

Since both tram companies were profitable, the city council decided to start another service—Kristiania Kommunale Sporveie (KKS, "Kristiania Municipal Tramways")—the first municipally owned tram operator in Norway. Sagene Ring was the first line, which opened on 24 November 1899 from Sagene to Akersgata, where there was a connection onwards to Østbanen station using KES tracks. On 26 January 1901, a connection line was built from Tollbugaten to Kirkeristen in the city centre to avoid running on KES tracks.

A second KKS line was opened on 27 March 1900, from Nybrua, located on the KSS's Grünerløkka–Torshov Line, via Trondheimsveien to Rodeløkka. Named the Rodeløkka Line, the southern section would later become part of the Sinsen Line. From Nybrua to the city centre, KSS track was used. The depot was located at Rodeløkka. A third line opened on 28 August 1900, from Tollbugaten in the city centre southwards to Festningsbryggen at Vippetangen—the Vippetangen Line. Again, KSS track was needed to connect the line into the city centre. Twenty cars and twelve trailers were bought from Busch with electric components delivered from Schuk—stock that remained in service until 1967. The company failed to make any profits, and was sold to KSS in 1905.

Consolidation After the take-over in 1905, KSS was operating seven routes: Homansbyen–Oslo, Homansbyen–Sannergata, Munkedamsveien–Sannergata–Grefsen, Munkedamsveien–Vålerenga, Sagene – St. Hanshaugen – Kampen, St. Hanshaugen – Rodeløkka and Stortorvet–Vippetangen. KSS extended the Vippetangen Line on 8 November 1905, and opened an extension from Homansbyen to Adamstuen on 24 September 1909. KSS and KES agreed to link their two networks, and a connecting line opened on 1 May 1912 between Homansbyen and Rosenborg station on KES's Line 1. An extension of the Vestbanen Line to Skillebekk was finished on 2 November 1911.

This expansion caused the need for more rolling stock, and KSS took delivery of 42 trams from Falkenried and Skabo between 1912 and 1914. At long they were somewhat longer than the other trams. The new lines allowed the two companies to operate on each other's lines, and they introduced a common numbering scheme for the services. Several of the lines were serviced by two numbered routes, a system that remains in use today. From 1912, a number of additional connections were built between the KES and KSS networks, and the two companies started cooperating on certain lines. From 1921 to 1923, KSS bought an additional 22 trams from Hannoversche Waggonfabrik, Brill and Busch, commonly referred to as the HaWa Class. KSS had an annual ridership of almost 60 million in 1922.

Light rail

Holmenkolbanen

Holmenkolbanen ("The Holmenkollen Line") opened the city's first suburban light rail line, the Holmenkollen Line, in 1898. It ran from Majorstuen station northwestwards via 12 stations to Besserud station. Like all the later light rail lines, these were electric trams with a grade-separated right-of-way and proper stations instead of tram stops. Unlike the other suburban tram lines that were built later, the Holmenkollen Line was not extended into the city using on-street tracks. Instead, passengers had to change at Majorstuen station to KES streetcars. In 1909, the Holmenkollen Line started using wide suburban stock, when it replaced its original 1898 Class trams with 1909 Class stock. The long Smestad Line opened in 1912 as a two station branch line from Majorstuen to Smestad station south of the Holmenkollen Line. In 1916, the Holmenkollen Line was extended from Besserud northwards to Tryvann with six new stations. The last part, from Frognerseteren station to Tryvann, which was single track and used for freight was demolished in 1939.