North South MRT Line

Overview

As the name implies, the line connects central Singapore to both northern and southern parts of the island.

In the clockwise direction, the North South Line starts at Jurong East, where cross-platform interchange with the East West Line is possible. The line then passes through Choa Chu Kang, where it interchanges with the Bukit Panjang LRT, and Woodlands, where it will interchange with the Thomson-East Coast Line from 2019. Going further south, the North South Line passes through Bishan, where it interchanges with the Circle Line.

In the city, the North South Line interchanges with the Downtown Line at Newton. It then passes through Orchard at the western end of Orchard Road, where it will interchange the Thomson-East Coast Line from 2021. At the eastern end of Orchard Road, it interchanges with the North East Line and the Circle Line at Dhoby Ghaut. Cross-platform interchange with the East West Line is possible at City Hall and Raffles Place.

Most southbound trains terminate at Marina Bay, where one can transfer to the Circle Line, and from 2021, the Thomson-East Coast Line. Some trains however, terminate at Marina South Pier.

First phase of development

The North South line was the first MRT line in Singapore, with the first section from Yio Chu Kang to Toa Payoh opening on 7 November 1987. Nine more stations from Novena to Outram Park followed on 12 December 1987, with through service onto what is today the East West Line. The northern terminal was extended to Yishun on 20 December 1988 when Yishun and Khatib stations opened. Separate operation of the North South and East West Lines only started on 4 November 1989, when the extension to Marina Bay was opened.

Second phase of development (Woodlands Extension)

After the Branch Line opened in 1990, the Woodlands Extension MRT line was envisioned to close the gap between Yishun and Choa Chu Kang. During the initial planning of the line, Sembawang station was only intended as a provisional station to be built at a later date due to the underdevelopment of the town and Kranji station was not planned. But on the second round of planning, the government decided to build these station and omit Sungei Kadut station from the plan. Sungei Kadut station will be built later if the town's population justifies the necessity for the station. With the completion of the Woodlands Extension in 1996, the Branch Line became part of the North South Line and ceased to exist.

Jurong East Modification Project (JEMP)

The Jurong East Modification Project consisted of the construction of a new platform and the addition of a fourth track to Jurong East Station. It has been in use since 27 May 2011. Originally it opened from 7am to 9am, this was expanded from 27 December 2011 and it also opens during the evening peak hour.

North South Line Extension (NSLe)

A 1-kilometre (0.6 mi), one station extension from Marina Bay to Marina South Pier station was opened on 23 November 2014, one year earlier than originally planned. The extension serves the Marina South Pier and the Marina Bay Cruise Centre Singapore in Marina Bay.

Canberra station

On 27 April 2015, construction started on Canberra Station (NS 12) which will be built along an operational section of the line and costing S$90 million. Similar to Dover Station, the station platform will be of an elevated side platform layout. Construction is expected to be completed by 2019 to serve the upcoming developments near the station.

Installation of half-height platform screen doors

After the government announced plans to install half-height platform screen doors on the above-ground stations in January 2008, they were first installed at Jurong East and Yishun stations in 2009 as trial runs. Subsequently, installation began in May 2011 at Ang Mo Kio MRT Station. By 14 March 2012, Kranji MRT Station was the last station to put the platform screen doors into operation.

Timeline of stations opened

Timber to concrete sleeper replacement works

Timber sleepers are designed to last 15 to 25 years, and they have to be replaced when they are near the end of their lifespan, or when they show signs of significant wear and tear. The new sleepers installed will allow trains to move along the tracks smoothly and without the current speed restrictions. In order to carry out works at night when trains are not operational, train services were ended earlier on the North South Line. The sleeper replacement work was divided into three phases: Phase 1 (Marina Bay-Bishan), Phase 2 (Bishan-Admiralty) and Phase 3 (Admiralty-Jurong East), and were completed in April 2015. Marina South Pier station was exempted from the sleeper replacement work as it was recently built. After the completion of sleeper replacement works, the last train timings reverted to the original timings before the replacement works.

Resignalling works

A new signalling system, supplied by Thales, will replace the current aging signalling system on the North South Line. The new signalling system, costing $195 million, will reduce waiting times for trains during peak periods from the current 120 seconds to 100 seconds. The new system is expected to be operational from mid-March 2017. MRT trains are also progressively being retrofitted with new equipment on board to be compatible with the new signalling system.

Third-rail replacement

Replacement works on the third rail, which provides electricity to the trains, are ongoing. A new third rail is being installed to replace the current one in use since 1987 and this will increase reliability of the electrical system.

Line disruptions

On 15 December 2011, services between Bishan and Marina Bay stations were suspended due to 40 metres of the power rail being damaged between City Hall and Dhoby Ghaut stations. Trains along the stretch were stalled, causing a disruption to the train service for almost 5 hours. Train service fully resumed at 11.40pm.

On 17 December 2011, a similar fault caused a 7-hour disruption between Ang Mo Kio and Marina Bay stations. According to SMRT, the disruption was caused by damage to the third rail and the trains' collector shoes. Seven trains were damaged in this incident.

These two service disruptions on the North-South Line were the second worst ever since SMRT started operation for 24 years since 1987.

On July 7, 2015, the NSEWL was shut down due to massive power trips detected along the two lines. This was the worst breakdown in history after the December 2011 issue. Investigations have been completed and the cause has been narrowed down to damaged insulators which failed to supply power properly.

Stations

The North South Line's numbering scheme reserves station code "NS6" between Yew Tee (NS5) and Kranji (NS7) for future use. Notes: Every fourth southbound train will terminate at the actual terminus, Marina South Pier while the others terminate at Marina Bay, for example;

1st train: Marina Bay*2nd train: Marina Bay*3rd train: Marina Bay*4th train: Marina South Pier

Rolling stock

Trains operating on the line are the C151s, C651s, C751Bs, C151As and the future C151Bs. These trains operate from the Bishan Depot which serves maintenance and train overhaul facilities along the North South Line and Ulu Pandan Depot along the East West Line. The trains can also crossover to the East West Line as both the North South Line and East West Line are built as one system operating two different lines at both Jurong East and Raffles Place.

Train control

The North South Line is currently equipped with Westinghouse fixed block signalling system with Automatic train control (ATC) under Automatic train operation (ATO) GoA 2 (STO). The subsystems consist of Automatic train protection (ATP) to govern train speed, Automatic Train Supervision (ATS) to track and schedule trains and a Relay interlocking system that prevents incorrect signal and track points to be set.

The existing signalling system is currently phasing out and will be replaced by a new Thales SelTrac® Communications-based train control (CBTC) moving block signalling system

The new signalling system is expected to be operational by Q1 2017 and trains will run with Automatic train control (ATC) under Automatic train operation (ATO) GoA 2 (STO) . The subsystems consist of Automatic train protection (ATP) to govern train speed, NetTrac MT Automatic Train Supervision (ATS) to track and schedule trains and a Computer-based interlocking (CBI) system that prevents incorrect signal and track points to be set.

Automatic platform screen doors by Westinghouse were originally installed when the line opened and Automatic Platform Screen Gates were installed at a later date on elevated stations.