North-South Line

The North-South Line (NSL) is a subway line in YJJ City, operated by YJJ City Metro. Coloured red on the rail map, the line is approximately 1.6 kilometres (1.0 mi) long and currently serves 6 stations, with most of the line being above-ground. It runs from Parliament station (formerly named Lakeside) near the centre of the island to Island Tip station at the south of the island. The line operates for 24 hours a day, with headways of up to 3 minutes. All the trains on the NSL run with a sixteen-cart formation.

It is the third subway line to be built in YJJ City, with service beginning in 2021. The line was planned in two stages - the first stage going from Solutional Park to Island Tip in the south, and the second stage extending the line north to Shilin. However, in 2021, the line was extended by 1 station north to Parliament, with the remaining portion of stage 2 to be constructed when developments in the north of the island take place.

History
During the construction of the Lake Loop Line in 2020, YJJ City Metro started planning and constructing a new rail service that would run from the north of the island to the south, running through Solutional Park. As a result, when Solutional Park Station was constructed, two additional platforms were built to the sides of the Lake Loop Line platforms, in preparation for the upcoming North-South Line, which would allow cross-platform transfers for passengers transferring between these two lines.

The North-South Line was originally planned to continue southwards to Losning island, but was later scrapped and replaced with the Losning Gateway Monorail.

Initial developments
YJJ City Metro started construction of the North-South Line southwards of Solutional Park Station. The line initially had only 1 other station, Chiaki Station, and extension of the line further south was delayed as there were sudden plans to construct a new depot south of Chiaki, although those plans were later scrapped due to developments around the area.

Island Tip extension
Also known as Phase 1 of the North-South Line construction, 3 new stations were constructed - Mount Lipan, Inoriye, and Island Tip. A tunnel was dug through Mount Lipan to allow the North-South Line to go between Mount Lipan and Inoriye stations. At Island Tip, the southern terminus of the North-South Line, the bi-directional track merges into a single-track platform, with the opposite side of the platform allocated for what was to become the Losning Gateway Monorail.

Parliament extension
Also known as Phase 2 of the North-South Line construction, a new station north of Solutional Park was constructed, in what was then named Lakeside Station, but is now known as Parliament Station. The track between Solutional Park and Lakeside stations was supposed to run alongside the Lake Loop Line tracks, but due to the terrain along the tracks and increasing problems with the level crossing at Hillside Street, the tracks were instead moved underground.

With this, a major reconstruction of the Lake Loop Line tracks as well as Parliament Station began - involving a reconfiguration of track layout such that the upper platform of Parliament Station served the clockwise Lake Loop Line and northbound North-South Line trains, and the lower platform served the anticlockwise Lake Loop Line and southbound North-South Line trains.

Shilin extension
The YJJ City Metro announced that the construction of the last phase of the North-South Line towards Shilin was held off until further developments in the north of the island. Until now, no significant development has taken place in the north of the island, and the YJJ City Metro has not yet announced any expected opening date.