Grorud Line - History

History

In 1948, the municipalities of Oslo and Aker were merged, and the new municipality started planning an expansion of the suburbs, among other places in Groruddalen. On 15 September 1949, the Planning Office For the Suburban and Underground Lines was establish as a division within the new municipality. The first specific plans were launched in March 1954, and consisted of four branches, including one on the north side of Groruddalen, which would be built to Grorud. The plans originally consisted of terminus in the city center at Grønlands torg, with a possible extension to Nationaltheatret, where the line would intersect with Holmenkolbanen's light rails serving Oslo West. However, it was quickly decided that the terminus would be Jernbanetorget, which served the Oslo East Station.

Construction of the Grorud Line started in February 1956. Landwork and electrical equipment was contracted to developers, while the trackage was done by the Planning Office. The original plans called for the use of 600 to 650 volt (V) direct current (DC) fed via a pantograph, to allow comparability with the western light rail. This was later changed to 750 V DC via a third rail. This was chosen to allow a higher diameter, and thus a higher ampere, and easier maintenance. The system also took into use cab signaling and moving blocks, which were cutting edge technology at the time, and had only been implemented on the Stockholm Metro in Europe by then. While the permitted headway on the common sections was set to 90 seconds, it was set to 120 seconds on the Grorud Line. The original plans called for a depot on each of the lines, including the Grorud Line, but this was later changed to a central depot at Ryen.

The section from Tøyen to Grorud was opened on 16 November 1966, five months after the metro had opened with the Lambertseter Line, and as the first branch of the metro to not be converted from a light rail. The Grorud Line was extended on 3 March 1974 to Rommen, on 18 August to Stovner, and was completed on 12 December 1975 to Vestli. The line took into use T1000 electric multiple units which could be up to six cars long. Originally the service terminated at Jernbanetorget in the city center, in addition to a service which ran via the branch from Carl Berners plass to the Lambertseter Line, and terminated at Ryen. On 9 January 1977, the city center service was extended to Sentrum. However, this station was closed from 20 March 1983 to 7 March 1987, and reopened as Stortinget. From 8 April 1995, the trains on the Grorud Line continued all the way through the Common Tunnel to Blindern on the Sognsvann Line, which serves the main campus of the University of Oslo.

On 20 August 2003, Line 5 had its western terminus extended to Storo, which opened along with the first part of the Ring Line. In on 17 July 2004, during construction of the Ring Line, part of the tunnel collapsed, causing the Grorud Line to be closed for six months, causin the 40,000 daily riders to have to use a bus from Tøyen. On 22 August 2006, the Ring Line was opened from Carl Berners plass to Sinsen, resulting in the section from Tøyen to Carl Berners plass also being served by lines 4 and 6. In 2007, the system started taking delivery of the new MX3000 units which would replace the old stock. From 18 August 2008, the line's frequency was increased from four to eight trains per hour, although the extra trains terminate at Stortinget. By 2010, all T1000 stock had been retired.

Since 9 December 2012, the Grorud Line is connected with the Røa Line in the west.