Common Tunnel
The Common Tunnel, sometimes called the Common Line, is a long tunnel of the Oslo Metro which runs through the city center of Oslo, Norway. The name derives from the fact that all five lines of the metro use the tunnel, which runs from Majorstuen to Tøyen. The section has six stations, including the four busiest on the metro.
The tunnel was first built as two separate tunnels which were later connected. The Holmenkolbanen company opened the western section of the tunnel from Majorstuen via Valkyrie plass to Nationaltheatret in 1928. In 1966, the Oslo Metro opened, including the tunnel from Tøyen via Grønland to Jernbanetorget. In 1977, the eastern end was extended to Sentrum, but the extension was closed in 1983 because of water leakages. In 1987, the Sentrum station reopened as Stortinget, and became the terminus of both the western and eastern lines. By 1993, the western end had been upgraded to metro standard, Valkyrie plass was closed, and the first trains ran through the whole tunnel.
The section from Tøyen to Brynseng, although not completely located within the tunnel, is considered part of the Common Line. At Majorstuen, the line splits into three; the Røa Line, the Holmenkollen Line and the Sognsvann Line. At Tøyen, the line splits into the Lambertseter Line and the Grorud Line. The tunnel is the bottleneck of the metro, allowing 24 trains per hour in each direction west of Stortinget, and 28 east of Stortinget.
Route
The Common Tunnel is a long double track rapid transit line running east from Majorstuen to Tøyen and onwards to Brynseng. The section from Tøyen to Brynseng is partially above ground and is only sometimes considered part of the tunnel and the Common Line. At Tøyen, the Grorud Line branches and continues past Carl Berners plass as part of the same tunnel. From Carl Berners plass to Ensjø, there is a single-track branch, which allows trains access to the other eastern lines without having to change direction. Three stations serve the city center: Nationaltheatret, Stortinget and Jernbanetorget, while Majorstuen, Tøyen and Grønland serve mixed residential and commercial areas.Service
All five lines of the Oslo Metro, numbered 1 to 5, run through the Common Tunnel. Most services have a 15-minute headway, which is increased to 30 minutes in the late evening and early on Sundays. Two lines have more frequent service. Line 2, which runs on the Furuset Line, has its headway reduced to 7.5 minutes and runs the entire tunnel. Line 3 on the Østensjø Line also has extra trains that terminate at Stortinget giving a 7.5 minute frequency on the east side of the tunnel. Line 5 trains run once around the Ring Line before continuing to their final destinations and therefore make two passes through the tunnel on a complete journey. Travel time from Majorstuen to Tøyen takes eight minutes. The tunnel is the bottleneck of the metro, with a capacity for 24 trains per hour in each direction west of Stortinget, and 28 east of Stortinget.Transfer to the Oslo Tramway is available at four stations, Majorstuen, Nationaltheatret, Stortinget and Jernbanetorget. Transfer to the mainline railway is available at Nationaltheatret to the railway station with the same name, and at Jernbanetorget to Oslo Central Station. Nationaltheatret offers shorter transfer distance, but only serves trains along the Drammen Line. Interchange with buses is possible at all stations except Grønland. Majorstuen acts as an interchange between the western lines, while transfer between the eastern lines can be done at Tøyen. The public transport authority Ruter recommends that interchange between lines in the same direction should be made at Grønland.
History
West end
In 1898, the Holmenkollen Line was opened as a light rail between Majorstuen to Holmenkollen. The terminus at Majorstuen was an inconvenience for passengers as most people were bound for the city center and had to change to the street trams. For the operator Holmenkolbanen, there were two ways to solve the issue. They could sign trackage rights with Kristiania Elektriske Sporvei to use the Briskeby Line to reach the city center. Alternatively, a tunnel could be built to an underground station in the city center. Applications for a tunnel were sent to the municipality in 1901. However, disagreements as to whether the tunnel was to be considered a railway or tramway halted progress; the city considered the line a tramway while the company considered it to be a railway.A new application was submitted in November 1907, which proposed a single track line to the intersection of Karl Johans gate and Fredriks gate, and was estimated to cost 1.5 million Norwegian krone. The plans drew criticism from city officials, who stated that the line would take passengers away from the existing tram line and that it would stimulate migration to the areas along the Holmenkollen Line in the neighboring municipality of Aker, thus reducing the tax income for the city. In 1909, Oslo City Council stated in a letter to the government that they were opposed to the tunnel. On 9 June 1911, the city council had nonetheless changed its mind, and voted to accept the tunnel if the terminus was moved to the intersection of Karl Johans gate and Ruseløkkveien, but this was rejected by the company. On 27 May 1909, Aker Municipal Council voted in favor of the tunnel, and on 9 June 1911 the proposal was passed by the Parliament of Norway. Both municipalities wanted the redemption right, which would allow them to purchase the railway at a later date, but this was instead given to the state. On 15 December 1911, Holmenkolbanen received a concession through a royal decree, which would last for 60 years from the date of opening.
Construction on the central parts of the tunnel started in 1912. At the time, an agreement had not been reached with the municipality about the location of the terminus. In October, there was a landslip at Valkyrie plass, resulting in a cavity. Thirty properties sustained cracks and other damage, and the owners threatened Holmenkolbanen with a lawsuit to reclaim the cost of repairs. By October 1914, the tunnel works had been completed from Rosenborggaten to the statue of Karl Johan in the Palace Park. The issue of the terminus was still not resolved, and work was therefore halted. Holmenkolbanen were planning on building the line through the city center, and therefore wanted the terminus at Fredriks gate, while the municipality wanted it at Ruseløkkveien.
In 1915, the city launched a competition for a plan for city's light rail system. However, the invitations were not issued until two years later. The winner was announced in July 1918, and in September 1919, a municipal committee concluded on how the network should be expanded. Firstly, it proposed connecting the Lilleaker Line to Majorstuen. Secondly, it proposed a tunnel through the city center, from Majorstuen to Stortorvet and Vaterland, and onwards as an elevated line eastwards, along routes that closely resemble the current metro lines and the Ekeberg Line. From Stortorvet, a northern branch was proposed which would be built towards Kjelsås. Finally, the committee wanted a circular line north of the city center, closely resembling to the current Ring Line.
The proposal forced the municipality to reconsider the terminus of the tunnel. The executive committee supported terminating the tunnel at Eidsvolls plass, but this was rejected by the city council on 13 July 1920. Holmenkolbanen convinced the municipality to establish a committee to look into the specific issue. In September 1921, the committee proposed creating a temporary terminus, following Holmenkolbanen's route, in the square behind the National Theatre. This was under the condition that experts concluded that construction would be done without damage to surrounding buildings. The proposal was passed by the city council on 13 October 1921. In June 1922, an expert committee concluded that construction would be satisfactory.
Aker Municipality held an option to purchase the Røa Line, should the tunnel not be completed by November 1922. On 11 November 1922, the municipal council executed the option. Aker had recently established the tram company Akersbanerne, and merged the Røa Line into Akersbanerne from 1 November 1924. In June 1923, the executive committee voted to allow a temporary terminus at Nationaltheatret, given that Holmenkolbanen would be obliged to continue the line onwards to Studenterlunden. The company did not accept the new terms, and the city council finally passed a proposal that the company could accept on 3 April 1924. However, by then traffic had increased on the Holmenkollen Line, the Røa Line had been connected to Majorstuen, and the Sognsvann Line was under planning. This caused Holmenkolbanen to change the tunnel to double track. To finance the construction, the company borrowed NOK 11.5 million.
In 1925, Oslo District Court found Holmenkolbanen not guilty in the lawsuit over damages at Valkyrie plass. A concession was granted on 15 January 1926, which demanded that the tunnel open by the end of 1928. A change of plans moved the line's route to Valkyriegaten under Valkyrie plass, which allowed the cavity from 1912 to become a station, despite it only being from Majorstuen. Past Slottsparken, the original track had been built at an increased depth to allow for a future extension of the Drammen Line of the Norwegian State Railways to run above the light rail tunnel. By 1926, these plans had been discarded, and the second track was not built as deep.
The line was officially opened by King Haakon VII on 27 June 1928. It became the first underground railway in the Nordic countries, five years before Stockholm and six years before Copenhagen. The tunnel was long and trams used three to four minutes to run through it. It was used by two companies,: Holmenkolbanen and Akersbanerne, with Holmenkolbanen operating both the Røa Line and the Holmenkollen Line. The Sognsvann Line was to be connected to the tunnel from 10 October 1934, and the two companies needed to find an agreement for paying for trackage rights. After negotiations failed, a decision was made by the Ministry of Labour on 7 July 1932, which stated that Akersbanerne would have to pay the additional fares collected for transport passengers through the tunnel, less the cost of running trains on the section.
On 16 May 1931, the Supreme Court found Holmenkolbanen guilty in the lawsuit regarding the real estate damage, with the compensation payments making the company insolvent. This resulted in Aker Municipality purchasing the majority of Holmenkolbanen, and merged the Røa Line and Sognsvann Line into the company. In 1939, Bærumsbanen started construction of a branch from the Lilleaker Line to Majorstuen. From 15 June 1942, the Kolsås Line, as it was renamed, started running via the tunnel to the city center. Bærumsbanen became part of Oslo Sporveier in 1971.