North South MRT line

First phase of development

Toa Payoh station, the oldest station on the MRT line and the Singapore MRT system

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.^[4] The line was extended northward to Yishun on 20 December 1988 and it began independent operations on 4 November 1989, when the extension to Marina Bay was opened.

Second phase of development (Woodlands extension)

Woodlands MRT station

After the Branch Line opened in 1990, the Woodlands MRT line was envisioned to close the gap between Yishun and Choa Chu Kang.^[5] 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 Sembawang. Kranji station was not planned. But on the second round of planning, the government decided to build these stations 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 official opening of the Woodlands Extension on 10 February 1996, the Branch Line became part of the North South line.^[5]

Jurong East modification project

Jurong East MRT station before the project

The Jurong East modification project entailed the construction of a new platform and the addition of a fourth track to Jurong East station to reduce waiting times and crowding at the station during peak hours.^[6] The modification project was completed on 27 May 2011.^[7] The track and platform was initially opened during morning peak hours only, but since December 2011, they also operate during the evening peak hours.^[8]

North South line extension

A 1-kilometre (0.6 mi), one station extension from Marina Bay to Marina South Pier station was opened on 23 November 2014.^[9] This extension serves the Marina South Pier, the Marina Bay Cruise Centre Singapore and future developments in Marina Bay Downtown area.^[9] At first, only 1 in 4 of the southbound trains will terminate at Marina South Pier. The other three trains will still terminate at the ex-terminus, Marina Bay, possibly due to Low demand. This restriction was lifted on May 2017 due to the new signalling systems. The last time where this restriction was implemented was on the 10th of May 2017, which was Vesak Day holiday. more recently, Marina Bay bound trains was re-introduced to increase the frequency of the trains between Jurong East and Marina Bay, but this rarely occurs.

Canberra station

On 17 January 2013, the Land Transport Authority (LTA) announced that a feasibility studies was being conducted to create a station between Sembawang and Yishun stations.^[10] The feasibility studies was completed in 2014 and Canberra station will be built.^[11] Shortly later on 1 August 2014, LTA announced that construction will commence in mid-2015 and is expected to be completed in 2019.^[12] Construction works for Canberra station commenced on 26 March 2016.^[13] This station, which is an Infill station and will have side platforms, will be built along an operational section of the line between Sembawang and Yishun stations. The construction costs S$90 million^[14] and is expected to be completed by 2019 to serve upcoming developments near the station.^[15]

Installation of half-height platform screen doors

The government announced plans to install half-height platform screen doors on the elevated stations in January 2008.^[16] The first platform screen doors were installed at Jurong East and Yishun stations in 2009 as trial runs.^[17] Subsequently, installation began in May 2011 at Ang Mo Kio MRT station. On 14 March 2012, platform screen doors became operational on all surface stations on the North South line.^[18]

Timeline of stations opened

• 7 November 1987: Yio Chu Kang – Toa Payoh
• 12 December 1987: Toa Payoh – Raffles Place
• 20 December 1988: Yio Chu Kang – Yishun
• 4 November 1989: Raffles Place – Marina Bay
• 10 March 1990: Jurong East – Choa Chu Kang
• 10 February 1996: Yishun – Choa Chu Kang
• 23 November 2014: Marina Bay – Marina South Pier
• 2019: Canberra

Timber to concrete sleeper replacement works

Timber sleepers were replaced when they neared the end of their lifespan of 15 to 25 years. The new replacement sleepers, made out of concrete, have a significantly longer lifespan.^[19] Train services on the line were ended earlier to allow more time for the sleeper replacement works. All timber sleepers were replaced by April 2015. After the completion of the replacement works, train services resumed their normal operating hours.^[20]

Resignalling works

A new signalling system, supplied by Thales, will replace the current ageing signalling system on the North South line. The upgrading works will be completed in phases from 2016. The upgraded signalling system will shorten waiting times as trains will be able to run closer to each other.^[21] The new system was expected to become operational from mid-March 2017. MRT trains were also progressively retrofitted with new equipment on board to be compatible with the new signalling system.

The new system was tested on the evening of 28 March 2017, when train services were paused to facilitate the testing. Testing of the new system had been ongoing since August 2016.^[22] From 16 April 2017, the new system commenced full-day testing on Sundays for two months. The new C151B rolling stock were first introduced to the line on these testing days.^[23] Since 29 May 2017, the new signalling system has been operating full-day on the North South line.^[24]

While the fact is that the East West Line has not been fully switched for several stretches, on 21 November 2017, the Land Transport Authority and SMRT said that from 8 December 2017 to 31 December 2017, 17 East West Line stations from Tiong Bahru to Tuas Link, and 2 North South line stations from Bukit Batok to Bukit Gombak, will close earlier on Fridays & Saturdays (at 11pm) and open later on Saturdays & Sundays (at 8am) to facilitate enhanced maintenance works (with replacement of track circuits at Jurong East and Ulu Pandan Depot as well as the re-signalling project of East West and North South Line). MRT stations will be fully closed on 10 December 2017 and 17 December 2017 to allow for extended engineering hours. As such, northbound train services will terminate at Choa Chu Kang.^[25][26]

On 19 April 2018, SMRT announced that 7 stations from Khatib to Novena will close at around 11pm on Fridays and Saturdays, and open later at around 8am on Saturdays and Sundays in May. This is to facilitate the re-signalling system project of the North South Line between Khatib and Braddell.^[27][28][29]

On 17 May 2018, SMRT announced that 5 stations from Admiralty to Yio Chu Kang will close at around 11pm on Fridays and Saturdays, and open later at around 8am on Saturdays and Sundays in June. Train services will continue to run from 15 June 2018 to 17 June 2018 during the week of Hari Raya Puasa.^[30][31][32]

On 18 June 2018, SMRT announced that 7 stations from Bukit Gombak to Admiralty will close at around 11pm on Fridays and Saturdays in July. As a result, there will be no train services between Bukit Batok and Sembawang. For trains travelling between Jurong East and Bukit Batok, there will be an interval of up to 10 minutes.^[33][34][35]

On 18 July 2018, SMRT announced that 7 stations on the East West Line from Dover to Pioneer and 3 stations on the North South Line from Bukit Gombak to Jurong East will close at around 11pm on Fridays and Saturdays, and open later at around 8am on Saturdays and Sundays in August and September 2018. Train services will continue to run from 10 August 2018 to 12 August 2018, 17 August 2018 to 19 August 2018 and 14 September 2018 to 16 September 2018.^[36][37][38]

Third-rail replacement

Replacement works on the third rail, which provides electricity to the trains, were completed in August 2017.^[39] The new third rail replaced its 30-year-old predecessor, which was used since the opening of the line. The new electrical system is expected to make train services more reliable.^[40]

Damaged rail

On 15 December 2011, services between Bishan and Marina Bay stations were suspended due to damage sustained on 40 metres of power rail between City Hall and Dhoby Ghaut MRT stations. Trains along the stretch stalled, causing a 5-hour service disruption. Train service resumed fully at 11.40pm on that day.^[41][42]

On 17 December 2011, a similar fault caused a 7-hour disruption between Ang Mo Kio and Marina Bay stations.^[43][44] 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.^[45]

These two service disruptions on the North South line were among the worst ever since SMRT's inception in 1987.^[46]

Power trips

On 7 July 2015, the North South line along with the East West Line was shut down due to massive power trips detected along the line. This was the worst breakdown so far in SMRT's history. Investigations have been completed and the cause has been narrowed down to damaged insulators which failed to supply power properly.^[47]

New signalling system

During the first few months of testing of the new signalling system, there had been numerous occasions of major service disruptions, lasting up to 3 hours long.^[48][49] In light of the re-signalling system tests, SMRT has advised commuters to plan for longer traveling time on the line.^[50]

Bishan tunnel flooding

On 7 October 2017, train services between Ang Mo Kio and Marina South Pier stations were suspended in both directions for several hours due to flooding in the tunnels between Braddell and Bishan. A trackside fire between Raffles Place and Marina Bay stations further exacerbated the disruption. Train services between Marina South Pier and Newton were restored at about 9.20pm on the same day. Train services between Newton and Ang Mo Kio were fully resumed at around 2pm the following day. This incident caused a 20-hour service disruption.^[51] Investigations revealed that the disruption started during a torrential downpour. A malfunction in the tunnel's water pumping and drainage system caused rainwater to flood the tunnels rapidly.^[52]