Roslagsbanan is a narrow gauge commuter railway system in Roslagen, Stockholm County, Sweden. Its combined route length is and there are 38 stations. It is built to the Swedish three foot () gauge. The Storstockholms Lokaltrafik (SL) classifies it as "light rail" in its maps. The line starts in Stockholm at Stockholm East Station (Stockholms östra station, Stockholm Ö). It goes north and splits into three branch lines at the junction stations Djursholms Ösby and Roslags Näsby; the three branches terminate at Näsbypark, Österskär and Kårsta. It is double track between Stockholm and Viggbyholm and between Rydbo and Åkersberga. The rest is single track, but the line to Vallentuna was being doubled in 2012 and Rydbo-Åkers Runö in 2013. There are passing loops at some stations on the single track sections: at Altorp, Hägernäs, Österskär, Visinge, Täby kyrkby, Ormsta, Lindholmen and Kårsta. Following a 2017 agreement between the Swedish state, Stockholm County, and the affected municipalities, the line will be extended to the centrally located underground hub T-Centralen, with construction to begin in approximately 2022. History The present Roslagsbanan was once just the southern part of a large narrow gauge system throughout Roslagen and eastern Uppland, connecting Stockholm and Uppsala with ports, smaller towns and parts of the countryside and used for both freight and passenger transport. In 1885 the line from Stockholm East Station to Rimbo was opened, today the longest branch of Roslagsbanan. It was originally built and operated by the private enterprise Stockholm-Rimbo Järnväg (SRJ). In 1909 SRJ changed its name to Stockholm–Roslagens Järnvägar (with the same abbreviation) following the take-over of companies running adjacent lines. Roslagsbanan is one of the oldest electrified railway lines for public transport in Europe. The first Stockholm–Djursholm suburban section, Djursholmsbanan, was electrified in 1892, and at the time continued into the city center by way of the tram network, ending at Engelbrektsplan next to Humlegården. In the beginning of the 20th century and well into the 1950s, Djursholms Ösby, a branch station on Roslagsbanan, was one of the busiest railway stations in Sweden with trains stopping every three minutes with three different branches dividing from there, transporting people and goods. In the years following World War II, more and more of Swedish railways were nationalised through Statens Järnvägar (SJ), a fate also shared by Roslagsbanan. In 1969 Stockholm County took control over the Stockholm–Rimbo network (now referred to as 'Roslagsbanan') from