East West MRT line

Dover station, the first infill station on the MRT network.

Changi Airport station.

Tuas Link MRT station under construction.

Construction on a new infill station Dover station between Buona Vista station and Clementi station began in June 1988. 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.[11] Despite some opposition, the Land Transport Authority proceeded with the construction to serve commuters along Singapore Polytechnic with Dover housing estate.[12][13] On 18 October 2001, Dover was opened.[14] Prior to opening, test runs were conducted from 13 to 17 October 2001 when the trains stopped at this station but did not open their doors. Dover is the first station in the MRT network to be built as an infill station.[15]

The idea of extending the Mass Rapid Transit system to Changi Airport was reconsidered when Terminal 3 of the airport was being built.[16] Earlier plans had long been made for a new line branching off from the existing East West line at Tanah Merah,[17] with some conceptual plans showing a tentative route alignment up to the airport along Airport Boulevard, continuing beyond the airport to Changi Point, before turning southwest back towards the city along the eastern coasts. The plans were finally announced by then Deputy Prime Minister Lee Hsien Loong on 15 November 1996.[18] However, the new route alignment showed a deviation from previous plans[19][20], where the final plan involved in building only the first two stations of Expo, and Changi Airport, the latter being the underground station built between Terminal 2 and Terminal 3. The alignment of the station at the airport also switched perpendicularly to an east-west direction, such that the station leads to two of the terminals directly from either end of the station. The stations' designs were unveiled on 10 February 1998[21] with construction starting on 29 January 1999.[22] Expo and Changi Airport were opened on 10 January 2001 and 8 February 2002 respectively and currently operates under a shuttle service. Prior to 22 July 2003, train services from Boon Lay commences after the opening, but were later reverted to shuttle services due to low patronage.[23][24]. On 25 May 2019, it was announced that the Changi Airport Extension will be converted to become part of Thomson-East Coast line Extension (TELe) by 2040.[25]

The 3.8-kilometre (2.4 mi) Boon Lay extension was first announced by the LTA on 29 December 2004, set to serve residents from the Jurong West Town area and those working in the Jurong Industrial Estate.[26] The two stations, Pioneer and Joo Koon stations, officially opened on 28 February 2009.[27][28]

On 11 January 2011, the Tuas West extension, an extension of the East West line from Joo Koon to Tuas Link was announced. The extension has a span of 7.5 kilometres (4.7 mi), which spans a twin-tracked MRT viaduct, four above-ground stations and a 26-hectare depot to provide stabling and maintenance facilities for the additional trains that will be bought for the extension and to cater for future expansion of the line.[29] The viaduct is integrated with part of a 4.8-kilometre-long (3.0 mi) road viaduct along Pioneer Road, which will increase the road capacity to cope with anticipated increase in traffic. The stations are Gul Circle, Tuas Crescent, Tuas West Road, and Tuas Link. On 4 May 2012, the Land Transport Authority marked the start of construction of the Tuas West extension with a groundbreaking ceremony at the site of the future Tuas Link station.[30]

The extension began service on 18 June 2017.[31][32][33] During initial stages after opening, the westbound trains will alternate their terminus between Joo Koon and Tuas Link, where for every two trains, one train will terminate at the former, while the other train will terminate at the latter.[34]

On 25 August 2014, the Land Transport Authority announced that a new platform will be constructed and added to 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.[35]

On 26 October 2016, the Land Transport Authority awarded the civil contract to Lum Chang Building Contractors Pte. Ltd. to build a new platform at Tanah Merah and viaducts for a contract sum of S$325 million. In addition to the new platforms, the existing East West line tracks will be extended to connect the line to the new four-in-one East Coast Integrated Depot at Changi.[36] When completed in 2024, it will be the second station to have triple island platforms after Jurong East.

There were calls for platform screen doors (PSDs) to be installed at above-ground stations after several incidents in which passengers were killed or seriously injured by oncoming trains when they fell onto the railway tracks at above-ground stations. Underground stations already featured the doors since 1987. The authorities initially rejected the proposal by casting doubts over functionality and concerns about the high installation costs,[37] 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 its becoming a more common feature worldwide.[38] They were first installed at Jurong East, Pasir Ris, and Yishun stations in 2009 as trial runs.[39][40] On 31 August 2011, the LTA announced completion of the installation of PSDs along the East West line, with Expo being the last station on the line to receive the PSDs.[41] Installation of PSDs across both the North South and East West lines (NSEWL) were completed on 14 March 2012, 3 months ahead of schedule.[42]

• 12 December 1987: City Hall – Outram Park
• 12 March 1988: Outram Park – Clementi
• 5 November 1988: Clementi – Lakeside
• 4 November 1989: City Hall – Tanah Merah
• 16 December 1989: Tanah Merah – Pasir Ris
• 6 July 1990: Lakeside – Boon Lay
• 10 January 2001: Tanah Merah – Expo
• 18 October 2001: Dover
• 27 February 2002: Expo – Changi Airport
• 28 February 2009: Boon Lay – Joo Koon
• 18 June 2017: Joo Koon – Tuas Link

The timber sleepers on the East West line was required to be replaced as they were near the end of their 25-year lifespan. The replacement sleepers, made of concrete, have a significantly longer lifespan.[43] To speed up works, train services on the East West line was adjusted to end earlier. The work was divided into three phases: Phase 1 (Bugis - Tanah Merah), Phase 2 (Joo Koon - Jurong East, Tanah Merah - Pasir Ris) and Phase 3 (Jurong East - Outram Park). The sleepers were fully replaced on 18 February 2017.[44]

A new moving-block signalling system, supplied by Thales, replaced the former ageing fixed-block signalling system on the East West line. The new signalling system, costing $195 million, reduces waiting times for trains during peak periods from 120 seconds then to 100 seconds now.[45] The new system became operational between Pioneer and Tuas Link stations on 18 June 2017. Newer rolling stocks, such as the C151B and C151C, are equipped for use solely on the new signalling system.[46] Since 27 May 2018, the new signalling system has been operating full-day on the entire East West line.

Replacement works on the third rail, which provides electricity to the trains, were carried out between September 2015 and August 2017.[47] The new third rail replaced its 30-year-old predecessor and is expected to increase reliability of the East West line's electrical system.[48]

On 5 August 1993, before opening, a maintenance vehicle spilt oil on the tracks between Clementi and Jurong East. The first ten eastbound trains reported braking problems, then the eleventh train from Jurong stopped at the Clementi station for two minutes longer than scheduled due to it using its emergency brakes to stop at the station at 7.50 am, before being hit by another eastbound train when it failed to stop in time. 156 passengers were injured by the collision.[49]

During the evening peak hours on 7 July 2015, services on both the East West and North South lines were temporarily disrupted due to massive power trips detected along the line. A cause of the disruption was damaged insulators which caused a failure to properly supply power.[50] For this disruption that brought inconvenience to 413,000 commuters, LTA imposed a 'record' fine of S$5.4 million on SMRT.[51]

At about 11.08 am on 22 March 2016, two SMRT track-maintenance trainee staff were killed after a C151 train approaching Pasir Ris station ran over them,[52], resulting in a temporarily service delay between Tanah Merah and Pasir Ris for about 2.5 hours and affected at least 10,000 commuters.[53]

In a report, the two trainee staff joined SMRT in January 2016 and worked as technicians under a technical team of 15 staff led by a supervisor and were tasked to go down to the tracks to investigate an alarm triggered by a possible signalling equipment fault close by the station. 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.[54]

Patrick Nathan, SMRT vice-president, promised that "SMRT will review all safety protocols particularly those involving track access".[55] SMRT chief executive Desmond Kuek apologised for the incident and said SMRT will investigate how "the [two men] got hit by the train". SMRT fired both an engineer responsible for leading with the team and the train driver who was involved at the scene of the accident.

On 2 December 2016, SMRT was formally accused of failing to ensure that its employees complied with approved operating procedures when accessing the track; SMRT was then pleaded guilty to its charges on 28 February 2017 and incurred a S$400,000 fine.[56] Investigations are still ongoing against the two men, Teo Wee Kiat (SMRT's director of control operations) and Lim Say Heng, both charged for the incident.[57]

A second train collision occurred on 15 November 2017 at approximately 8.18am, where two C151A trains collided at Joo Koon MRT station. A train fault caused the first train heading in the direction of Tuas Link to stall at the station. A minute later, a second train stopped behind the first and then "moved forward unexpectedly" to cause the collision. 38 people, which include two SMRT staff were hospitalized.[58][59][60][61][62][63]

Train services between Tuas Link and Joo Koon stations were temporally suspended on both directions for two hours on the day itself and the entire day on 16 November 2017, resulting that the westbound trains would temporarily terminate at Joo Koon.[64][65]

An update by the Land Transport Authority (LTA) & SMRT on 16 November 2017 stated that LTA and SMRT have decided to isolate for up to one month the operations of the Tuas West extension, which runs on the new signalling system, from the rest of the East West line, which runs on the old signalling system, enabling LTA engineers to carry out further assurance checks together with Thales. The train was switching systems when the collision took place.[66] 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. Train services between Joo Koon and Gul Circle were temporarily suspended until its resumption on 28 May 2018; between the suspension a free bridging bus service is available between the two stations. 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 North South or East West line were to conduct track renewal works with early weekend closures and later station openings.[67]