Circle Line (Singapore)

Planning

Plans for the Circle Line were first announced by Minister for Communications and Information Yeo Ning Hong who said the line would connect Singapore’s major housing estates. However, he added that such a route would only be built once Singapore's population reached four million and new housing estates were developed farther from the city centre.^[4] At the time, the MRT network followed a radial pattern, with lines extending outward from the city centre.^[5]

In October 1994, Communications Minister Mah Bow Tan announced a proposed overground light rail system designed to serve the National Stadium, Beach Road, Marina Centre, Shenton Way, and Marina South, with interchanges at Dhoby Ghaut and Kallang.^[6][7] In October 1997, the Land Transport Authority (LTA) invited companies to provide architectural and engineering services for a planned Marina Line (MRL). The proposed 12 km (7.5 mi) underground line would comprise 18 stations, running from Kallang station through Marina Centre and Marina South before interchanging with the North East Line at People's Park. A branch line from Marina Centre to Dhoby Ghaut was also proposed, while further branches and extensions to Paya Lebar and Tanjong Pagar were under consideration.^[8] In June 1998, Mah announced the government would proceed with the construction of the MRL, which was planned to have 20 stations and operate medium-capacity driverless trains. Construction was expected to begin in 2000 at an estimated cost of S$1.75 billion. The line was also designed with provisions to expand train capacity from four to six cars as passenger demand increased.^[9] Parsons Brinckerhoff and Mott MacDonald were appointed as architectural and engineering consultants for the MRL.^[10]

In October 1999, the LTA announced that an outer circle line would link Buona Vista and Paya Lebar via Bishan and Serangoon. The number of planned stations on the MRL also increased to 24. Construction of the segment between Dhoby Ghaut and Marina Centre would be prioritised given demand along the Bras Basah corridor, while construction of the other sections would be deferred due to lack of developments in the planned Marina Downtown.^[11] In 2001, the first six stations of the MRL from Dhoby Ghaut to Boulevard were announced, with plans to connect the MRL from Stadium station to the Outer Circle Line at Paya Lebar. The Outer Circle Line would also loop back to Marina South via World Trade Centre.^[12] Subsequently in April that year, communications minister Yeo Cheow Tong announced that the Marina Line would be built as the first phase of the Circle Line, alongside the announcement of the second phase that would span 5 kilometres (3.1 mi) from Stadium to Upper Paya Lebar Road.^[13][14]

Construction

Industry observers anticipated that Trans-Island Bus Services (TIBS) would operate the CCL in accordance with the Singapore Government's initiative for multi-modal operators.^[15] TIBS had partnered with Regie Autonome des Transports Parisiens (RATP) for its bid to operate the line.^[16] However, the LTA ultimately awarded the contract to SMRT Corporation in August 2001. The LTA justified its decision based on SMRT's track record, financial strength, and customer service.^[15][17]

Construction of the CCL officially began on 5 March 2002 with a groundbreaking ceremony at Bras Basah Park.^[18][19] At the ceremony, Yeo announced that the 34-kilometre (21 mi) CCL would be built in five stages and completed by 2010.^[19] Stage 3 of the CCL, which comprises five stations from Bartley to Marymount, was announced in January 2003.^[20] The 13 stations of CCL Stages 4 and 5 from Thomson to HarbourFront were announced in December 2003.^[21][22] This segment included three planned shell stations – Caldecott, Bukit Brown and Haw Par Villa.^[b] These station were to be opened only when their surroundings were more developed.^[22][25]

On 20 April 2004, the tunnels linking to Nicoll Highway station caved in along with a 100 m (330 ft) stretch of the Nicoll Highway. The collapse of a tunnel retaining wall caused soil subsidence,^[26] creating a hole 100 metres long, 130 metres wide, and 30 metres deep (328 by 427 by 98 ft).^[27] Four people were killed and three were injured.^[28][29][30] The LTA halted work at 16 of the 24 CCL excavation sites for review.^[27][31] A Committee of Inquiry (COI) concluded that the incident was caused by human error and organisational failures.^[32] The strut-waler support system was poorly designed and weaker than it should have been, with a lack of monitoring and proper management of data.^[33] Although the LTA initially said that the collapse happened without warning,^[34] the COI report revealed that there were already "warning signs", such as excessive wall deflections and surging inclinometer readings, which were not addressed seriously.^[33][35] The report pointed out a lack of safety culture at the site and made several recommendations to improve the safety of construction projects,^[33] which the government accepted.^[32][36] Nicoll Highway station was rebuilt 100 m (330 ft) south of the original site along Republic Avenue, with a new tunnel alignment between the Millenia and Boulevard stations.^[37] Due to the tunnels' collapse, the completion date of CCL Stage 1 was delayed from 2007 to 2009.^[38]

In March 2004, the LTA launched a public polling exercise to name the stations along the CCL, marking the first time the general public was invited to participate in the naming process to foster a greater sense of community ownership.^[39][40][41] The public could choose between two LTA-proposed names for each station or suggest their own, provided the names accurately reflected the area's locality, history, and multi-cultural heritage.^[39] The names for the CCL Stages 1 to 3 stations were finalised in July 2005.^[42][43] A subsequent naming poll for the CCL Stages 4 and 5 stations attracted 634 respondents – 152 more than the previous poll. These station names were finalised in December 2005.^[44][45]

On 14 June 2005, the LTA announced plans for the Downtown Extension (DTE), which was intended to be a branch of the CCL^[46] Comprising five stations from Milennia (now Promenade) to Chinatown,^[47][48][49] it would serve the development of the Downtown at Marina Bay, a planned business and financial hub.^[48] Yam Ah Mee, the then-chief executive of the LTA, also stated that the agency was studying further extensions to the DTE, including an eastward extension to Kim Chuan Depot and a westward extension linking the line to the Bukit Timah Line.^[50] In 2007, transport minister Raymond Lim announced that the DTE would instead be incorporated into the Downtown Line (DTL).^[51] Another branch to Marina Bay station via Bayfront was announced in April that year.^[52]

Construction of the CCL platforms at Dhoby Ghaut required stabilising the existing underpass above linking the North East Line (NEL) and North–South Line platforms. Seven caisson piles were installed to enhance the support of the underpass and capping beams were then constructed to form the supporting system.^[25] At Esplanade, the arterial routes of Bras Basah Road and Nicoll Highway had to be diverted through more than 10 phases.^[53] The station was constructed using the top-down method to minimise the impact of noise and dust pollution on the surrounding developments. Diaphragm walls were built to minimise ground movement. With the roof constructed first, construction could proceed under all weather conditions while allowing the early reinstatement of Bras Basah Road and War Memorial Park.^[54] Two East–West Line viaduct piers at Paya Lebar station had to be underpinned. Using concrete walls, beams, and a powerful jacking system, they transferred the weight of the viaduct so they could safely cut away the old piles.^[55][56]

During excavation of the CCL tunnels beneath Serangoon station, contractors encountered significant groundwater seepage, causing ground settlement and the NEL station to sink by 1 centimetre (0.39 in).^[57] Works were suspended while water was pumped out, and NEL trains were required to slow when entering or leaving the station.^[58] The tunnel was subsequently redesigned, with jet grouting and enhanced monitoring introduced to detect further settlement.^[57][59] At Holland Village, the excavation pit was only 6 m (20 ft) away from the Willyn Ville Condominium, requiring vigilant ground testing and wall deflection monitoring to ensure the building's safety.^[60] Similarly, Pasir Panjang was dug in soft ground just 10 metres (33 ft) from a road viaduct and in close proximity to residential homes and shophouses.^[61]

The Building and Construction Authority halted tunnelling works near Telok Blangah in August 2007 following the ground settlement of two road lanes near the junction of Telok Blangah Road and Alexandra Road.^[62] A section of Cornwall Gardens Road near Holland Road caved in on 24 May 2008 during tunnelling works between Holland and Farrer Road stations. While no one was injured, the sinkhole led to the disruptions of utilities in the area.^[63]

Opening

The Straits Times reported that the CCL Stage 3 stations were "in advanced stages of completion" in September 2007, with architectural, engineering, and mechanical works being carried out and expected to be finished by mid-2008. In January 2008, the Stage 3 stations' completion date was moved earlier from 2010 to mid-2009.^[64][65] Two of the planned shell stations – Thomson and West Coast – would also be fitted out and opened with the other CCL stations.^[66] The LTA started conducting test runs on the Stage 3 stations, with the expected commencement date set for June 2009.^[67] In February 2009, transport minister Raymond Lim announced that CCL Stage 3 would open on 30 May,^[68] though it was later moved to 28 May.^[69][70] An open house was held for the Stage 3 stations on 23 May,^[71] before operations commenced on 28 May.^[72] An opening ceremony was held at Bishan station, presided by deputy prime minister Teo Chee Hean.^[73][74]

Due to the Nicoll Highway collapse, the expected opening date for CCL Stage 1 was delayed by two years from 2007 to 2009.^[38] In August 2009, transport minister Lim announced that Stages 1 and 2 of the CCL would open by the first half of 2010;^[75][76] this was later announced to be 17 April.^[77][78] An open house was held on 5 April 2010.^[79][80] Stages 1 and 2 of the CCL commenced operations on 17 April 2010,^[81][82] with transport minister Lim holding an opening ceremony at Bras Basah station the day before.^[83]

Tunnelling works for the CCL were completed in August 2009,^[38] marked by a tunnel breakthrough ceremony at Farrer Road.^[84][85] As announced by transport minister Lui Tuck Yew during his visit to the CCL Stages 4 and 5 stations on 1 August 2011,^[86][87] the segment began revenue service on 8 October of that year.^[88][89] The CCL extension to Marina Bay opened on 14 January 2012, with an official opening ceremony held on the day before.^[90][91][92]

Circle Line Stage 6

Stage 6 of the CCL (CCL6), which LTA said would "close the circle" by linking HarbourFront to Marina Bay,^[93] was first announced by transport minister Lui in January 2013 as part of the 2013 Land Transport Master Plan.^[93][94] Details of the CCL6 were finalised in October 2015. The 4 km (2.5 mi) segment would include three stations – Keppel, Cantonment and Prince Edward, and was expected to be completed by 2025. The project also includes the expansion of Kim Chuan Depot.^[95] Prince Edward station was renamed to Prince Edward Road following a naming poll held in 2017.^[96][97][98]

To facilitate construction works of Cantonment station, the old train platform canopy structures were relocated to a restoration yard nearby in November 2017.^[99] Tunnelling works for the CCL6 began on 25 July 2019 with the launch of the Tunnel Boring Machine (TBM) at Keppel station. The TBM will tunnel from Keppel to the existing CCL HarbourFront station.^[100] To construct the tunnels between Keppel and Cantonment, the Keppel viaduct was underpinned with new micro piles. Three bored piles were removed for the tunnelling works.^[101] During tunnelling between the Cantonment and Prince Edward Road stations, structures were erected to protect the Tanjong Pagar railway station's facade and interior, and monitoring instruments were installed to watch out for any building settlement.^[102] CCL6 tunnelling works were completed on 12 January 2022, with a final tunnel breakthrough from Prince Edward Road into Cantonment.^[103][104]

From January to April 2024, one platform at the Telok Blangah and HarbourFront stations were closed to facilitate track integration works with the CCL6 stations.^[105] A new Integrated Supervisory Control System (ISCS), which monitors and manages power supply, communications and station facilities on the CCL, has also been installed in 2025.^[106] Final system integration testing works are ongoing in April and May 2026.^[107][108]

Due to delays caused by the COVID-19 pandemic, the completion date of CCL6 was shifted to 2025.^[109] In December 2024, transport minister Chee Hong Tat announced that CCL6 would only commence operations in the first half of 2026.^[110]

Nicoll Highway collapse

On 20 April 2004, a section of the tunnel being built for the Circle Line collapsed, when a retaining wall used in the tunnel's construction gave way. This incident occurred near the proposed site of the Nicoll Highway station, not far from the Merdeka Bridge. The accident left a collapse zone that was 150 metres (490 ft) wide, 100 metres (330 ft) long, and 30 metres (98 ft) deep. Four workers were killed, and three were injured.^[111]

A criminal inquiry found the main contractor Nishimatsu Construction Company and joint venture partner firm Lum Chang Construction Company and their officers, as well as key Land Transport Authority officers responsible for the collapse. Several other officers and subcontractors were reprimanded and issued warnings in connection with the accident.^[111]

As a result of this accident, the first phase of the Circle Line, previously scheduled to open in 2008, was completed in 2009 instead. The affected station has been shifted about 100 metres (330 ft) away from the accident site and is now located at Republic Avenue.

This accident also resulted in stricter safety regulations for the construction of all future MRT lines. The shifting of the Nicoll Highway station also meant it can no longer serve as a terminus for the Bukit Timah Line, partially influencing the creation of the current Downtown Line.^[112]

Other incidents during construction

On 16 August 2007, the Building and Construction Authority (BCA) issued a stop-work order and revoked the contractor's tunnelling permit after a 7-metre (23 ft) stretch of two lanes close to the junction of Telok Blangah Road and Alexandra Road sank about 20 centimetres (7.9 in) that evening.^[113]

A section of the road above a construction site near Holland Road caved in on the morning of 24 May 2008, creating a hole. The hole, directly in front of two private houses along Cornwall Gardens, measured 8 by 7 metres and was 3 metres deep. No one was injured, but the road was temporarily closed to traffic.^[114]

Major disruptions

From 17 January 2026 to 9 April 2026, a three-month scheduled service disruption took place on sections of the Circle Line for tunnel strengthening works. During this period, trains ran on a single platform on the eastern stretch between three stations – Mountbatten, Dakota and Paya Lebar.^{[115][116][117]} This disruption was deemed necessary for longer engineering hours due to a phenomenon called "tunnel squatting".^[118] This was because portions of the Circle Line were constructed in soft marine clay, a material that naturally compresses over time. This soil settlement subjects the tunnels to external pressure, leading to the circular structure gradually deforming into an elliptical or oval shape which needed to be reinforced with steel plates.^[118][119]

Network

The Circle Line is the second line in Singapore to be completely automated and driverless, following the North East Line, and is among the world's longest driverless rapid transit lines.^[3] It is also the first medium capacity line in Singapore.^[120]

Capacity and overcrowding

In 2011, the Circle Line was projected to reach a final ridership of 400,000 passengers per day upon full completion.^[121] However, the line quickly surpassed expectations due to population growth and rising commuter demand, with reports of overcrowding emerging as early as October 2011 when Stages 4 and 5 opened.^[122] By May 2015, daily ridership had reached 398,000,^[123] and by 2023, the line averaged over 450,000 passengers per day.^[1]

Key interchanges such as in Serangoon and Bishan in particular have frequently experienced overcrowding especially during peak hours due to the stations' narrow platforms and the operational constraint of running only three-car trains.^[124] Commuters have reported waiting times of up to 30 minutes during peak hours to board a train.^[125] In response, the LTA has announced that 23 new trains will be added to the line in 2026 to further reduce headway.^[126]

Route

The 35.5-kilometre (22.1-mile) Circle Line forms an incomplete loop from Dhoby Ghaut in the Central Region of Singapore, north to Serangoon and Bishan, and south to HarbourFront, with a branch from Promenade to Marina Bay station which will be extended to HarbourFront in 2026. The fully-underground circular route also makes several links with the other MRT lines.^[120] The line begins at Dhoby Ghaut station, which has an interchange with the North–South Line and North East Line, going eastwards and paralleling Bras Basah Road and Raffles Boulevard, before joining the Circle Line extension at Promenade station, which also interchanges with the Downtown Line. From Promenade station, the line goes northwards and towards the east, passing beneath the Kallang Basin. Between the Stadium and Dakota stations, the line parallels Stadium Boulevard and Old Airport Road, then the line continues northwards and follows the route of Paya Lebar Road and Upper Paya Lebar Road between the Paya Lebar (which interchanges with the East–West Line) and Tai Seng stations.

The line curves and continues westwards between the Bartley and Marymount stations, also interchanging with the North East and North–South lines at Serangoon and Bishan stations respectively, and then it continues in a general southwest direction between Caldecott and Kent Ridge, the former having an interchange with the Thomson–East Coast Line, passing through Bukit Brown Cemetery between the Caldecott and Botanic Gardens stations. The line also interchanges with the Downtown Line at Botanic Gardens station and the East–West Line at Buona Vista station. After Kent Ridge station, the line curves eastwards, paralleling the West Coast Highway and then terminating at HarbourFront station, where it interchanges with the North East Line.

From 2026, upon the completion of Stage 6, the Circle Line will continue eastwards from HarbourFront, paralleling Keppel Road and Ayer Rajah Expressway, and joins the Circle Line extension at Marina Bay station. The Circle Line extension from Marina Bay to Promenade station generally parallels the Downtown Line and Bayfront Avenue, also passing underneath Marina Bay Sands at Bayfront station, which it serves and has cross-platform interchange with the Downtown Line. Also, end-destination number 9 and 10 will be replaced by clockwise and counter-clockwise loops.

Stations

Station codes for the line are orange, corresponding to the line's colour on the system map.^[128] All stations have island platforms, with the exception of Promenade and future infill station Bukit Brown.

Legend

Elevated	Line terminus	Transfer outside paid area
Ground-level	Wheelchair accessible	Bus interchange
Underground	Civil Defence Shelter	Other transportation modes

List

More information Station code, Station name ...

Station code	Station name	Images	Interchange; Adjacent transportation	Opening	Cost
CC1  NS24  NE6	Dhoby Ghaut		North–South Line   North East Line	17 April 2010; 16 years ago	S$343.94 million [129][130][131][note 1][note 2]
CC2	Bras Basah		—
CC3	Esplanade
CC4  DT15	Promenade		Downtown Line  ― Marina Centre
CC5	Nicoll Highway		—		S$573 million [132][133][note 1][note 3]
CC6	Stadium
CC7	Mountbatten				S$322 million [134][135][136][56][note 4][note 5]
CC8	Dakota
CC9  EW8	Paya Lebar		East–West Line
CC10  DT26	MacPherson		Downtown Line		S$356.1 million [137][138][139][note 4][note 6]
CC11	Tai Seng		—
CC12	Bartley			28 May 2009; 17 years ago	S$63.5 million[140][141]
CC13  NE12	Serangoon		North East Line  ― Serangoon		S$155.95 million[142]
CC14	Lorong Chuan		—		S$65.0 million[143][144]
CC15  NS17	Bishan		North–South Line  ― Bishan		S$82.2 million[144][141][145]
CC16	Marymount		—		S$167.7 million
CC17  TE9	Caldecott		Thomson–East Coast Line	8 October 2011; 14 years ago	S$391.59 million [146][note 7][note 8]
CC18	Bukit Brown		—	TBA
CC19  DT9	Botanic Gardens		Downtown Line	8 October 2011; 14 years ago
CC20	Farrer Road		—
CC21	Holland Village				S$399.91 million [147][148][note 7][note 9]
CC22  EW21	Buona Vista		East–West Line  ― Buona Vista Ghim Moh
CC23	one-north		—
CC24  JE	Kent Ridge		Jurong Region Line (East)  (early-2040s)
CC25	Haw Par Villa		—		S$335 million [149][note 10][note 11]
CC26	Pasir Panjang
CC27	Labrador Park
CC28	Telok Blangah
CC29  NE1	HarbourFront		North East Line  ― HarbourFront
Stage 6 (under construction, to be ready by mid-2026)
CC30	Keppel		—	Mid-2026; 1 month's time	S$313.8 million [150][151][152][note 12]
CC31	Cantonment				S$205 million [153][154][155][note 13]
CC32	Prince Edward Road		Shenton Way		S$310.8 million [156][157][note 14]
Circle Line Extension
CE2  NS27  TE20 / CC33  NS27  TE20	Marina Bay		North–South Line   Thomson–East Coast Line	14 January 2012; 14 years ago	S$348.4 million [158][159][160][note 15]
CE1  DT16 / CC34  DT16	Bayfront		Downtown Line		S$463 million [note 16]
Continues onto  CC4  DT15  Promenade.

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Depots

More information Depot name; Lines, Location ...

Depot name; Lines	Location	Images	Line-specific stabling capacity	Cost	Opening
Kim Chuan	Hougang		70 trains (until 2026) 133 trains (from 2026)	S$1.507 billion[161][162][163][150][151][c]	4 March 2009; 17 years ago

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