[5] The 15-kilometre (9.3 mi) eastern extension to Tanah Merah station opened on 4 November 1989, which also marked the start of independent operations as the East–West Line.

[6][7] The 6-kilometre (3.7 mi) line extension to Pasir Ris station was opened ahead of schedule on 16 December 1989[7][8] with a sneak preview beforehand.

[9] Boon Lay station opened on 6 July 1990, marking the completion of the initial MRT system.

[11] The building of the station was met with reservations by some members of the public over the small area it serviced and there were criticisms over the spending of "taxpayers' money" chiefly for use only by students of one educational institution.

[12] Despite some opposition, the Land Transport Authority proceeded with the construction to serve commuters along Singapore Polytechnic with Dover housing estate.

The plans were finally announced by then Deputy Prime Minister Lee Hsien Loong on 15 November 1996.

[38] On 25 August 2014, the Land Transport Authority announced that a new platform will be constructed at Tanah Merah, enabling faster travel and shorter waiting times for commuters heading towards Expo and Changi Airport on the Changi Airport branch line of the East–West Line.

[39] On 26 October 2016, the Land Transport Authority awarded the civil contract to Lum Chang Building Contractors Pte.

The authorities initially rejected the proposal by casting doubts over functionality and concerns about the high installation costs,[41] but made an about-turn later with the government announcing plans to install half-height platform screen doors on the elevated stations on 25 January 2008, citing lower costs due to it becoming a more common feature worldwide.

[42] They were first installed at Jurong East, Pasir Ris, and Yishun stations in 2009 as trial runs.

[52] A new railway turnback located at Pasir Ris station, the eastern terminus of the line, was announced by the Land Transport Authority on 29 Jun 2018.

[57] At about 11:08 a.m. on 22 March 2016, two SMRT track-maintenance trainee staff were run over and killed by a C151 train approaching Pasir Ris station,[58] resulting in a temporarily service delay between Tanah Merah and Pasir Ris for over two hours that affected at least 10,000 commuters.

An operator cited that they were granted access to the tracks, but did not coordinate with a Signal Unit in the station to ensure trains could not travel in the area where the team was.

SMRT fired both an engineer responsible for leading with the team and the train driver who was involved at the scene of the incident.

The engineer who led the inspection team was charged with negligence causing death under the Penal Code[62] and was subsequently sentenced to 4 weeks in jail.

[76] Train service on the line resumed on 20 November, with the Tuas West extension between Gul Circle and Tuas Link using the new signalling system and the section between Pasir Ris and Joo Koon, together with the Changi Airport Branch continuing to run on the old signalling system.

Continuous service between Pasir Ris and Gul Circle resumed on 28 May 2018, with the permanent activation of the new CBTC system; since the incident, selected portions of either the North–South Line or East–West Line were closed to conduct track renewal works with early weekend closures and later station openings.

[79][80][81] On Thursday night, SMRT announced that no trains will run between Jurong East and Buona Vista for a third straight day, with full service expected to resume the following Monday.

However, in an update at about 4:30pm on 29 September 2024, the target date for restoration of full service was pushed back to Tuesday.

[82][83] On September 30, SMRT and LTA announced that full service would fully resume on October 1, with westbound train speeds being reduced from the usual 60-80 kilometres per hour (37.5-50mph) to 40 kilometres per hour (25mph) until October 3, as part of a standard process after rail replacements.

Shuttle bus services may be provided throughout the duration of the early closures and late openings for affected commuters.

[87][88] As its name implies, the East–West Line connects central Singapore to both eastern and western parts of the island, with an additional branch between Changi Airport and Tanah Merah, which operates as a separate shuttle service.

The line runs mostly on overhead viaducts but goes underground in the city area between Kallang and Redhill, Bedok and Kembangan, and between Expo and Changi Airport.

[99][100][101] These models of rolling stock were introduced to boost the capacity on both the North–South and the East–West lines in order to cope with increasing ridership.

The stretch of track between Pioneer and Tuas Link stations was equipped with the new signalling system which came into use in June 2017.

As the section of track between Pioneer and Joo Koon support 'mixed-mode' of both signalling systems, trains terminating at either Joo Koon or Tuas Link would have to change signalling modes at Pioneer MRT station as trains terminating at Joo Koon would proceed to a turn back siding which was built as part of the TWE which only supports the new signalling system.

Eastbound trains towards Pasir Ris would have to change back to the old signalling system at Pioneer MRT station.

[77] When the line was first opened, full-height platform screen doors supplied by Westinghouse were installed at underground stations.

[131] Nevertheless, the LTA reversed its decision and made plans to install half-height platform screen doors on elevated stations on 25 January 2008.

[132][133] The first platform screen doors by ST Electronics were installed at Pasir Ris, Jurong East and Yishun stations in 2009 as trial runs.