and Tuas. KPE consists of a 9 kilometres-long tunnel, which is the longest subterranean road tunnel in Southeast Asia. During its construction, the KPE tunnel was the world's sixth longest underground road project. Originally envisioned as two separate expressways, the 2.8 kilometres-long Kallang Expressway (KLE) and the 9.2 kilometres-long Paya Lebar Expressway (PLE), they were officially combined into one in 1991. Plans to build the KLE surfaced as early as 1981, and would have become the shortest expressway in Singapore if it was not merged into the KPE. The future North–South Corridor (NSC) will link Kallang and the city centre with northern Singapore. The section of NSC within Kallang will be fully underground. Public transit Rail Rail transport in Kallang exists as the Mass Rapid Transit (MRT). Kallang has the largest number of MRT stations outside of the Downtown Core, at 11, including the two stations currently under construction. At present, four MRT lines have stations in Kallang: East West Line, North East Line, Circle Line and Downtown Line. The following stations are currently in service: Kallang Lavender Little India Farrer Park Boon Keng Stadium Mountbatten Bendemeer Geylang Bahru Kallang will also be served by these upcoming stations on the Thomson–East Coast Line, slated for completion in 2023: Tanjong Rhu Katong Park A 16 kilometres-long "Kallang Line" was mentioned in the 1996 White Paper published by the Land Transport Authority (LTA). This MRT line was supposed to run along the banks of the Kallang River, connecting Ang Mo Kio MRT station in the north with Lavender MRT station in the south. The plan to build the Kallang Line was later shelved. On 20 April 2004, a section of the Circle Line tunnel collapsed during construction. This accident became known as the "Nicoll Highway collapse" and happened west of the Merdeka Bridge, near present-day Nicoll Highway MRT station. Bus Kallang is served by an established bus network that connects the area with other parts of Singapore. Unlike other towns, Kallang does not have its own feeder bus services which ply between the neighbourhoods of Kallang, likely due to the relatively fewer housing precincts in Kallang as compared to other new towns that are established primarily for residential purpose. Lorong 1 Geylang Bus Terminal is the only bus terminal located in Kallang. It sits opposite Kallang MRT station, along its namesake Lorong 1 Geylang. The Kallang area has no bus interchange or