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104-400: The Circle Line ( CCL ) is a medium-capacity Mass Rapid Transit (MRT) line in Singapore . It runs in a loop from Dhoby Ghaut station in the city-centre to HarbourFront station in the south via Bishan station in the centre of the country. It also has a branch to Marina Bay station from Promenade station, which will be extended to HarbourFront station from 2026 to form

208-469: A nonprofit organisation , also categorises several public transport systems as "light metro". The main reason to build a light metro instead of a regular metro is to reduce costs, mainly because this system employs shorter vehicles and shorter stations. Light metros may operate faster than heavy-rail rapid transit systems due to shorter dwell times at stations, and the faster acceleration and deceleration of lighter trains. For example, express trains on

312-613: A bridge spanning the Kallang and Rochor rivers. The construction contract for Kallang Bridge was awarded to Paul Y. Construction Company in association with Messrs Hume Industries and Messrs Sime Darby for $ 4.485 million ( US$ 15   million in 2021 ) in December 1954. On 22 June 1956, Kallang Bridge was renamed Merdeka Bridge to reflect "the confidence and aspiration of the people of Singapore". Merdeka Bridge and Nicoll Highway opened on 17 August that year; crowds gathered on both ends of

416-410: A complete loop. Coloured orange on the rail map, the fully-underground line is approximately 35.5 kilometres (22.1 mi) long with 30 stations. Travelling from one end of the line to the other takes about an hour. The line was the fourth MRT line to be opened on the network, with the first stage, from Bartley to Marymount station, commencing operations on 28 May 2009. The next stage to Dhoby Ghaut

520-476: A fire in the Traction Safety Shutdown System (TSSS) cubicle was detected, triggering a power shutdown along the entire line as part of a safety feature. This comes one day after a power fault that affected the entire line as well. The fire was extinguished, and traction power was restored within 10 minutes. Full train services resumed at 8.15pm. After the incident, SMRT said that the procurement of

624-521: A fully grade separated exclusive right-of-way . In some cases, the distance between stations is much longer than typically found on heavy rail networks. An MCS may also be suitable for branch line connections to another mode of a heavy-capacity transport system, such as an airport or a main route of a metro network. The definition of a medium-capacity system varies due to its non- standardisation . Inconsistencies in international definitions are even reflected within individual countries. For example,

728-478: A hole 100 m long, 130 m wide, and 30 m deep (330 by 430 by   100 ft). One person was found dead and three others, who were working on driving machinery at the bottom of the site, were initially reported missing. They included a foreman who had helped evacuate his workers to safety when the site collapsed but did not escape in time because a flight of exit stairs collapsed. Three injured workers were taken to hospital for treatment; two of them were discharged

832-417: A medium-capacity system (as it used shorter 4-car SP1950 trains, compared to 7- to 12-car trains on other heavy rail lines) but can attain up to 32,000 p/h/d which is comparable to the passenger capacity of some full metro transit networks. However, it was built to the full heavy rail standard as it was designed to be extended. Full-length, 8-car trains were deployed on the line in advance of its extension and

936-403: A network of steel king posts , walers, and struts to keep the site open. At about 3:30   pm local time on 20 April 2004, tunnels linking to Nicoll Highway station caved in along with a 100-metre (300-foot) stretch of Nicoll Highway near the abutment of Merdeka Bridge. The incident happened when most of the workers were on a tea break. The collapse of a tunnel's retaining wall created

1040-587: A replacement TSSS cubicle with enhanced features, is being expedited, as well as system improvements will be made, including enhancements to the Circle Line's signalling and PA systems, as well as fail-safe and fail-soft features. 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. It

1144-509: A section of single track rail) can only achieve lesser headways (e.g. every 15 minutes) which result in lower passenger volume capacities, and thus would be more accurately defined as "light metro" or "medium-capacity" systems as a result. An example is the LA Metro B/D line during the COVID-19 pandemic, as headways were reduced to every 12-20 minutes on each line. In addition to MCS, light metro

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1248-441: A traffic lane. On 25 April 2004, a part of Nicoll Highway running from Mountbatten Road to Stadium Drive was restored for motorists accessing the area around National Stadium of Singapore . Crawford Underpass, which runs under Merdeka Bridge, reopened on 29 April. After the collapsed site was refilled, the highway was rebuilt on bored piles so the rebuilt stretch would not be affected by future excavation works. Reconstruction of

1352-487: Is a common alternative word in European countries, India, and South Korea. In some countries, however, light metro systems are conflated with light rail . In South Korea, light rail is used as the translation for the original Korean term, "경전철" – its literal translation is "light metro", but it actually means "Any railway transit other than heavy rail, which has capacity between heavy rail and bus transit". For example,

1456-471: Is also the first medium capacity line in Singapore. 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

1560-496: Is among the world's longest driverless rapid transit lines. It is also the first medium capacity line in Singapore, with each Circle Line train, the Alstom Metropolis C830 and C830C , having a three-car configuration. The Circle Line dates back to 1989, when then-Minister for Communications and Information, Yeo Ning Hong , stated that such a system would be "feasible when the population reaches four million", noting

1664-420: Is created from relative lower capacity and/or train configuration comparisons to other heavy rail systems in the same area. For example, the train in an MCS may have a shorter configuration than the standard metro system, usually three (though, in some cases, just two) to six traincars , allowing for shorter platforms to be built and used. Rather than using steel wheels, rubber-tyred metro technology, such as

1768-626: Is the list of former-MCSs that either developed into a full rapid transit system, or which are no longer in operation: Nicoll Highway collapse The Nicoll Highway collapse occurred in Singapore on 20 April 2004 at 3:30   pm local time when a Mass Rapid Transit (MRT) tunnel construction site caved in, leading to the collapse of the Nicoll Highway near the Merdeka Bridge . Four workers were killed and three were injured, delaying

1872-551: The Disaster Assistance and Rescue Team and Search Platoon, arrived as reinforcements to search for the missing workers. The first dead victim was found at 6:07   pm. All machinery was turned off as the SCDF used a life-detector device in the collapse site but nothing was detected and sniffer dogs were brought into the search. The second body was recovered at 11:42   pm on 21 April. Prime Minister Goh Chok Tong visited

1976-514: The Downtown Line . On the other hand, a further extension towards Upper Paya Lebar was announced on 28 April 2001. The Marina Line was eventually merged with a planned Light Rail Transit line that went from Paya Lebar to Buona Vista via Serangoon and Bishan to form Circle Line Stage 3 on 20 January 2003, and subsequently Circle Line Stage 4 and 5 on 12 December 2003 when Stage 4 was extended from Buona Vista to World Trade Centre to close up

2080-518: The Housing and Development Board . The COI called for 143 witnesses to provide evidence, including 14 experts. The COI visited the site on 23 April and the inquiry was originally scheduled for 1 June. Because all parties involved would need two-and-a-half months to prepare due to complex technical content, the inquiry was postponed to 2 August. At the first hearing of the inquiry, the inquiry panel established that there were "fundamental" design flaws in

2184-700: 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

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2288-637: The Kelana Jaya , Ampang and Sri Petaling lines as "light rail transit" systems; when originally opened, the original Malay abbreviations for the lines, PUTRA-LRT ( Projek Usahasama Transit Ringan Automatik /Automatic Light Transit Joint Venture Project) and STAR-LRT ( Sistem Transit Aliran Ringan /Light Flow Transit System) did not clearly distinguish between light rail and light rapid transit. Some articles in India also refer to some "light metro"-type systems as "light rail". The Light Rail Transit Association (LRTA),

2392-495: The Land Transport Authority (LTA), Singapore's transport agency, said it had no evidence of an explosion and that the witnesses might have mistaken the loud sound of the collapse for an explosion. As a precautionary measure, gas supply to the damaged pipe was shut off. The Singapore Civil Defence Force (SCDF) arrived at the site at 3:42   pm. After rescuing the three injured people, specialist SCDF units, such as

2496-451: The Marymount to HarbourFront stations) on 8 October 2011. A two-station extension to Marina Bay opened on 14 January 2012. On 17 January 2013, then-Minister for Transport, Lui Tuck Yew , announced Circle Line Stage 6 which would "close the circle", set to be completed by 2025. The 4 km extension will run between Marina Bay and HarbourFront. The extension will connect commuters between

2600-735: The New York City Subway are about as fast as the Vancouver SkyTrain , but these express trains skip most stops on lines where they operate. Medium-capacity systems have restricted growth capacities as ridership increases. For example, it is difficult to extend station platforms once a system is in operation, especially for underground railway systems, since this work must be done without interfering with traffic. Some railway systems, like Hong Kong and Wuhan, may make advance provisions for longer platforms, for example, so that they will be able to accommodate trains with more, or longer cars, in

2704-653: The Taiwan Ministry of Transportation and Communications states that each MCS system can board around 6,000 to 20,000 passengers per hour per direction (p/h/d or PPHPD), while the Taiwan Department of Rapid Transit Systems (TCG) suggests an MCS has a capability of boarding around 20,000 to 30,000 p/h/d, and a report from the World Bank places the capacity of an MCS at 15,000 to 30,000 p/h/d. For comparison, ridership capacity of more than 30,000 p/h/d has been quoted as

2808-505: The U Line in Uijeongbu utilises VAL system, a variant of medium-capacity rail transport, and is therefore categorised "light metro" by LRTA and others, though the operator itself and South Korean sources refer to the U Line as "light rail". Busan–Gimhae Light Rail Transit is also akin to a light metro in its appearance and features, thought the operator refers it as a "light rail". Likewise, Malaysian officials and media commonly refer to

2912-570: The VAL system used on the Taipei Metro , is sometimes recommended, due to its low running noise , as well as the ability to climb steeper grades and turn tighter curves, thus allowing more flexible alignments. Fully heavy rail or metro systems generally have train headways of 10 minutes or better during peak hours. Some systems that qualify as heavy rail/metro in every other way (e.g. are fully grade separated ), but which have network inadequacies (e.g.

3016-455: The Circle Line uses electric multiple unit (EMU) trains operating in a three-car configuration, with four doors per side on each carriage and can accommodate of up to 931 passengers in each trainsets. It consists of 40 first-generation Alstom Metropolis trains were supplied under contract C830 . They are built in France by Alstom between 2006 and 2008. They are stabled at Kim Chuan Depot , which

3120-571: 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. Station codes for the line are orange, corresponding to the line's colour on the system map. All stations have island platforms, with the exception of Promenade and future infill station Bukit Brown . Legend List The Circle Line's numbering scheme reserves station code "CC18" for future use. The rolling stock for

3224-703: 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

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3328-591: The HarbourFront to Marina Bay stations and expand the rail network to the southern edge of the Central Business District. On 29 October 2015, LTA announced the station locations for Stage 6, with the working names of the stations being Keppel , Cantonment , and Prince Edward . Tenders were called for construction between 2016 and 2017. On 15 May 2017, the LTA invited the public to send in suggestions for names of

3432-523: The LTA and Nishimatsu were responsible for the collapse. Those who received warnings included Nishimatsu personnel, an LTA engineer, soil engineers, and L&M Geotechnic and Monosys, which were engaged in soil analysis. Three others were given counselling by the Manpower Ministry. Nishimatsu and three of its personnel faced criminal charges under the Factories Act. A qualified personn from LTA, who

3536-553: The MRL was incorporated into the CCL. The contract for the construction of Nicoll Highway station and tunnels was awarded to a joint venture between Nishimatsu Construction Co Ltd  [ ja ] and Lum Chang Building Contractors Pte Ltd at S$ 270 million (US$ 200 million ) on 31 May 2001. In 1996, the joint venture was investigated for breaching safety rules in a previous project; infringements included loose planks on its scaffolding. In 1997,

3640-641: 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

3744-606: The accurate installation of the beams. Nishimatsu supervisors were warned about failing support structures on the day of the collapse but instructed the subcontracting site supervisor Nallusamy Ramadoss to continue installing struts and pouring cement on the buckled struts to strengthen the wall. The struts continued to bend further before the collapse; Ramadoss warned his workers of the danger and evacuated them to safety. Some workers said they were not warned of any danger or given any safety briefings but escaped in time. Other workers also reported hearing "thungs" of bent walers before

3848-401: The bored tunnels, the contractor implemented perforated vertical drains, and ground improvement efforts were undertaken in the vicinity of tunnel drainage sumps and cross-passages. On 29 September 2005, the LTA marked the start of the new Nicoll Highway station's construction with a groundbreaking ceremony, during which the diaphragm walls were first installed. Due to the tunnel collapse,

3952-520: The bridge to witness the opening ceremony. By August 1967, the highway and the bridge had been widened to accommodate seven lanes. Nicoll Highway station was first announced in November 1999 as part of the Mass Rapid Transit 's (MRT) Marina Line (MRL), which consisted of six stations from Dhoby Ghaut to Stadium . In 2001, Nicoll Highway station became part of Circle Line (CCL) Stage 1 when

4056-893: The buckling walls and for compromising safety due to flawed monitoring of instruments. The company's design manager and project coordinator were each fined S$ 200,000 (US$ 100,000 ) for giving "blind approval" to the flawed designs. The LTA and the Building and Construction Authority (BCA) introduced new safety protocols such as a new Project Safety Review which identifies and reduces risks of hazards. Safety requirements are now set above industry standards, which include doubling scaffold access for evacuation routes in an emergency and one man-cage at each excavation area for rescuers. LTA no longer allows contractors to outsource their own geotechnical firms, but appoints an independent monitoring firm to check on instruments. Contractors are also no longer permitted to design and supervise their own temporary works, with

4160-411: The cable bridge swayed, and everything around them trembled and collapsed. The inquiry was adjourned on 30 August and resumed on 6 September. An interim report that was released to the government on 13 September noted "glaring and critical shortcomings" in the construction project that were seen in other ongoing construction projects. Additionally, inexperienced personnel had been appointed to monitor

4264-439: The cavities and the lack of visibility in flooded areas. The LTA detected stability problems on 23 April at 1:05   am and grouting was implemented to stabilise the soil while water was pumped out from cavities, allowing rescuers to further investigate. Heavy rain in the afternoon caused soil erosion and halted the search. Because of the instability of the collapsed area that could bury rescue workers and cause more damage to

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4368-409: The collapse, Nicoll Highway and the adjacent Promenade station were planned to have a cross-platform interchange with an unspecified future line; that had to be realigned because the new Nicoll Highway station had no provision to be an interchange. The new tunnels were designed by Aecom consultants and tunnels to the previous site were demolished with special machinery from Japan. The new station

4472-478: The collapse. This was because soil-monitoring instruments, which were placed roughly in the centre of the collapsed area, had been buried and the site supervisor Chakkarapani Balasubramani did not take the readings, although he raised the issue with the main contractor and was told the instruments would be dug out. Nishimatsu engineer Arumaithurai Ahilan said he saw "nothing alarming" in the soil-movement readings and accused Balasubramani of lying in testimony. While he

4576-464: The companies damaged underground telecommunications cables in another underpass construction project. The site was on land reclaimed during the 1970s and consisted of silty old alluvium and a 40 m (130 ft) layer of marine clay resulting from sea-level changes of the Kallang Basin. The station and tunnels were constructed from the "bottom-up": cut-and-cover excavation was supported by

4680-472: The construction of the Circle Line (CCL). The collapse was caused by a poorly designed strut-waler support system , a lack of monitoring and proper management of data caused by human error, and organisational failures of the Land Transport Authority (LTA) and construction contractors Nishimatsu and Lum Chang. The Singapore Civil Defence Force extracted three bodies from the site but were unable to retrieve

4784-521: The construction project. To address the lack of safety culture stated in the report, the COI restated several recommendations from its interim report to improve the safety of construction projects. The government accepted the report's recommendations. Family of the victims were given S$ 30,000 (US$ 20,000 ) each as unconditional, ex gratia compensation by Nishimatsu and Lum Chang. Heng's family received an additional S$ 380,000 (US$ 280,000 ) in settlements from

4888-402: The consultation of experts on the causes of weakening of the retaining wall, began on 24 January 2005 and concluded on 2 February. More than 170 witnesses were brought in during the 80 days of the inquiry. The COI released its final report on 13 February 2005; it concluded the incident was preventable and had been caused by human error and organisational failures. The strut-waler support system

4992-419: The contractor had rejected the design. The LTA technical advisor for design management had advised against excavation of the site due to incorrect data. In the two months before the cave-in, the tunnel's retaining walls had moved more than the maximum allowed. The contractors had petitioned the LTA to increase the agreed maximum threshold of movement. The contractors had miscalculated the amount of stress on

5096-772: The control centre. The Circle Line is equipped with Alstom Urbalis 300 Communications-based train control (CBTC) moving block signalling system on the MASTRIA system with Automatic train control (ATC) under Automatic train operation (ATO) GoA 4 (UTO). The subsystems consist of Automatic train protection (ATP) to govern train speed, Iconis Automatic Train Supervision (ATS) to track and schedule trains and Smartlock Computer-based interlocking (CBI) system that prevents incorrect signal and track points to be set. Train Data Management System (TDMS) which concentrate and dispatch

5200-415: The cost of construction had risen to nearly S$ 10 billion. Due to the collapse, the station was relocated to a new site two-thirds the size of the original 100 metres (330 ft) away. Three stations on the Circle Line were initially designed as 'shell stations', but the decision was made to open two of them, Caldecott and Haw Par Villa (previously Thomson and West Coast respectively), leaving Bukit Brown as

5304-441: The costs of CCL construction works, alongside inflation and increasing costs of concrete. Following the collapse, the LTA closed off the stretch of Nicoll Highway from Middle Road to Mountbatten Road. Alternative roads leading into the city, including the junction of Kallang Road and Crawford Street, were widened to accommodate diverted traffic. The LTA also converted a bus-only lane at Lorong 1 Geylang towards Mountbatten Road into

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5408-434: The creation of the current Downtown line . 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. A section of the road above a construction site near Holland Road caved in on

5512-560: The fault might reoccur and decided to replace the main circuit breaker that had also tripped. They powered down the TSSS cubicle as a safety precaution, but caused another circuit breaker to trip, which led to the loss of power on the entire line. The maintenance team had failed to seek clearance from the head of CCL operations before proceeding with the maintenance, and such maintenance work should have been done during engineering hours while trains were not running. On 18 September 2024, at around 8pm,

5616-404: The first span triggering the collapse of the 610-metre (2,000 ft) bridge, the first and second spans of the bridge were cut to isolate the first span. This also allowed Crawford Underpass beneath the bridge to be reopened. This project began on 23 April and was completed on 28 April. Eight prism points and five tiltmeters were installed to monitor any bridge movements. The collapsed site

5720-585: The foreman. The ceremony, initiated by MP Irene Ng, was attended by Heng's wife and his two children. The bench was funded by the Tampines Changkat Citizens' Consultative Committee. A commemorative stone and plaque were also erected at the former site marking where Heng was believed to be buried. On every anniversary, workers from Kori Construction visit the site to offer prayers and incense in honour of Heng. The COI determined that Nishimatsu, L&M Geotechnic, Monosys and thirteen professionals from

5824-721: The future. Taipei Metro , for example, constructed extra space for two extra cars in all its Wenhu Line stations. The following is the list of currently-operating MCSs which are categorised as light metros by the Light Rail Transit Association (LRTA) as of March 2018 , unless otherwise indicated. The list does not include, for example, monorails and urban maglev , despite most of them also being "medium-capacity rail system". Bombardier Innovia Metro 300 Trains: 4-car configuration AMPANG AND SRI PETALING LINES: CRRC Zhuzhou LRV Trains: 6-car configuration SHAH ALAM LINE: 3-car CRRC Light Rail vehicles The following

5928-495: The highway began on 24 August 2004 and the new stretch of highway reopened on 4 December. On 4 February 2005, the LTA announced Nicoll Highway station would be relocated 100 m (330 ft) south of the original site along Republic Avenue with a new tunnel alignment between Millenia (now Promenade ) and Boulevard (now Stadium ) stations. The LTA decided against rebuilding at the original site due to higher costs and engineering challenges posed by debris left there. Prior to

6032-613: The incident, the collapsed site was refilled, and Nicoll Highway was rebuilt and reopened to traffic on 4 December 2004. Heng Yeow Pheow, an LTA foreman whose body was never recovered, was posthumously awarded the Pingat Keberanian (Medal of Valour) for helping his colleagues to safety ahead of himself. In response to inquiry reports, the LTA and the Building and Construction Authority (BCA) revised their construction safety measures so they were above industry standards. The CCL tunnels were realigned, with Nicoll Highway station rebuilt to

6136-412: The last due to unstable soil. An inquiry was conducted by Singapore's Manpower Ministry from August 2004 to May 2005, after which three Nishimatsu engineers and an LTA officer were charged under the Factories Act and Building Control Act respectively, and all four defendants were fined. The contractors gave S$ 30,000 (US$ 20,000 ) each to the families of the victims as unconditional compensation. Following

6240-424: The last obtained before the collapse at 3:30   pm. The steel beams to hold up the walls had not been constructed when workers dug further into the site. LTA supervisor Phang Kok Pin, whose duty was to confirm the correct installation of support beams, said he visited the pit typically once or twice a day. He conducted only sporadic inspections and heavily relied on reports from Nishimatsu contractors to confirm

6344-545: The line is now expected to be completed by 2026 instead due to delays caused by the COVID-19 pandemic . Tunnelling works for the CCL6 were completed on 12 January 2022, with a final tunnel breakthrough from Prince Edward Road station into Cantonment station. The tunnels between Cantonment station and the adjacent Prince Edward Road station were constructed only 6.7 metres (22 ft) below the former Tanjong Pagar Railway Station . Prior to

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6448-635: The line was extended into the Tuen Ma line in June 2021. Two other lines, the Disneyland Resort line shuttle service to Hong Kong Disneyland Resort since 2005 and the South Island line since December 2016, are also classified as MCS because of their shorter trains and smaller capacity, however they use the same technology as the full-capacity rapid transit lines. Generally speaking, medium capacity designation

6552-473: The line with the construction of Stage 6, a tender for additional trains for the line was published on 31 March 2017. To increase the capacity of the Circle Line for Circle Line Stage 6, an additional 23 third-generation Alstom Metropolis trains were supplied under contract C851E with the first train set arrived in Singapore on 11 March 2022. The automated CBTC system on board relies on "continuous two-way digital communication" between each controlled train and

6656-451: The link and to provide connectivity from the west to Sentosa, becoming the Circle Line. On 8 August 2001, SMRT won the bid and was appointed the operator of the Circle Line. Names for the stations for the first three stages of the Circle Line were finalised in July 2005 after the Land Transport Authority (LTA) conducted a public consultation exercise on the naming of stations. In November 2005,

6760-434: 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. As a result of this accident, the first phase of the Circle Line, previously scheduled to open in 2008,

6864-412: 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. On 20 September 2011, a power fault disrupted train services at all 16 stations on the Circle Line. The four-hour delay left thousands of commuters stranded during rush-hour. It

6968-473: The names of the stations in Stages 4 and 5 were finalised. Construction started on 13 March 2002 for Stage 1, 5 September 2002 for Stage 2, May 2003 for Stage 3, and January 2005 for Stages 4 and 5. Initially planned to be opened in stages from 2006 to 2010, at an estimated cost of S$ 6.7 billion, the Nicoll Highway collapse delayed the opening of the first stage to 2009. When the line fully opened on 8 October 2011,

7072-478: The only unopened station on the line. The first section of the line, Stage 3, a 5 kilometres (3.1 mi) five-station segment stretching from Bartley to Marymount, opened on 28 May 2009. Initial ridership on this section was lower than estimated, at 32,000 passengers per day (ppd) instead of the estimated 55,000 ppd. Tunneling works for the entire line were completed on 17 August 2009. Stages 1 and 2 started operations on 17 April 2010, followed by Stages 4 and 5 (from

7176-508: The other MRT lines. The line begins at Dhoby Ghaut station, which has an interchange with the North–South and North East lines, 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

7280-414: The platform level at Dakota station. 27,000 passengers were affected by the disruption during the four hour delay, with bus bridging services plying the Circle Line route. In late August 2016, intermittent signal interference led to a five-day series of train disruptions. The issue reappeared in November. A team of data scientists explored the data and discovered via a Marey chart visualization that it

7384-403: The retaining walls but gave the LTA repeated assurances that their calculations were in order. Nishimatsu's senior on-site supervisor Teng Fong Sin claimed ignorance of the significance of the trigger values taken from the retaining wall. Teng said even if he had been aware of the significance, he lacked the authority to halt the ongoing work. No readings were taken in the two days leading up to

7488-444: The rolling stock information with fixed equipment. The IAGO Waveguide communications network has the capability to transmit video and is almost maintenance-free. Base stations are located within the signalling equipment room. Automatic platform screen doors supplied by Westinghouse provide safety for commuters, offering protection from arriving and departing trains. Medium-capacity rail system Since ridership determines

7592-399: The safety of the retaining wall system. The interim report recommended a more-effective safety management system, an industry standard for the safety of temporary works, and a higher standard of reliability and accuracy in monitoring data. The interim report was released so "corrective measures" could be implemented for other construction projects. The LTA project manager Wong Hon Peng, who

7696-452: The same day. No motorists were driving along the stretch of road when it collapsed and others stopped in time. Three power cables were severed, resulting in a 15-minute blackout in the Esplanade , Suntec City , and Marina Square regions. The collapse of the highway damaged a gas service line. From initial reports, eyewitnesses heard explosions and saw flames flashing across the highway;

7800-500: The scale of a rapid transit system, statistical modeling allows planners to size the rail system for the needs of the area. When the predicted ridership falls between the service requirements of a light rail and heavy rail or metro system, an MCS project is indicated. An MCS may also result when a rapid transit service fails to achieve the requisite ridership due to network inadequacies (e.g. single-tracking ) or changing demographics. In contrast with light rail systems, an MCS runs on

7904-490: The site on 21 April; he praised the coordination between the SCDF and the Public Utilities Board (PUB) for the ongoing rescue efforts and expressed relief at the small number of fatalities. Goh extended his condolences to the families of the victims and said the rescue efforts should be the priority rather than apportioning blame. He added the government would convene a public inquiry. President S R Nathan visited

8008-405: The site on 22 April to pay tribute to the rescue workers. A third body was recovered from the site on 22 April at 12:15   am. The SCDF had to vertically excavate through a pile of rubble and debris located within three cavities, two of which were flooded and blocked by twisted steel beams and struts. The operation presented significant difficulty due to the limited space for manoeuvring within

8112-462: The site to protect the soil. While the surrounding buildings were assessed to be safe, they were later monitored for stability with additional settlement markers and electro-level beams that were installed at the nearby Golden Mile Complex . The LTA halted work at 16 of the 24 CCL excavation sites so these could be reviewed. Near the incident site, the approach slab before the abutment of Merdeka Bridge had collapsed. To prevent displacement of

8216-511: The slow population growth and demand. Feasibility studies for the proposed line commenced on 11 October 1994. The line, then named the Marina Line, was first announced on 16 October 1997. The line would serve Marina Centre and the new downtown at Marina South, with multiple branches to Chinatown and Dhoby Ghaut via the National Stadium to either Kallang or Paya Lebar stations. The line

8320-447: The south of the original site underneath Republic Avenue. The station and tunnels opened on 17 April 2010, three years later than planned. The Singapore Improvement Trust first planned Nicoll Highway in the late 1940s to relieve the heavy rush-hour traffic along Kallang Road and provide an alternative route from Singapore's city centre to Katong and Changi . These plans were finalised in July 1953; they included construction of

8424-465: The standard for metro or "heavy rail" standards rapid transit systems, while light rail systems have passenger capacity volumes of around 10,000 to 12,000 p/h/d or 12,000 to 18,000 p/h/d. VAL (Véhicule Automatique Léger) systems are categorised in the medium-capacity rail systems because their manufacturer defines their passenger capacities as being up to 30,000 p/h/d. In Hong Kong , MTR 's Ma On Shan line could, in some contexts, are classified as

8528-469: The surrounding area, the search for the foreman, Heng Yeow Pheow, was called off at 3:30   pm. The Nicoll Highway collapse led to the deaths of four people: Safety measures were implemented after the collapse to minimise further damage to the collapsed area. A damaged canal had to be blocked up to prevent water from the Kallang River from entering the site, and canvas sheets were laid on slopes in

8632-441: The three MRT stations or propose to keep their current names. The Keppel and Cantonment stations kept their names, while Prince Edward station was changed to Prince Edward Road station. Construction of Stage 6 commenced in late 2017. A joint venture – by China State Construction Engineering (The Singapore branch) and Nishimatsu Construction – won the contract to build the new Keppel station and its associated tunnels. Stage 6 of

8736-464: The three construction firms involved with the collapse and S$ 630,000 (US$ 460,000 ) in public donations. The money from the public donations was diverted into a trust fund that was set up by Heng's Member of Parliament Irene Ng from which expenses for his children's upkeep could be drawn until 2019. Nine SCDF officers who were involved in the search and rescue efforts were awarded the Pingat Keberanian (Medal of Valour). SCDF Commissioner James Tan, who

8840-452: The tunnelling works, an extensive survey was conducted to ensure that the tunnels do not cross through the building's foundations. Structures were erected to protect the railway station's facade and interior, and monitoring instruments were installed to watch out for any building settlement. To construct the tunnels to Keppel station, the Keppel viaduct had to be closely monitored while underpinning

8944-432: The tunnels. Power was restored by 6.05pm, and SMRT staff had to manually drive the stalled trains to their next stations, causing delays of about 30 minutes,. Normal train services fully resumed by 7.40pm. Investigations show that the disruption was first caused by a circuit breaker that tripped in the Traction Safety Shutdown System (TSSS) cubicle. After SMRT's maintenance team reset the circuit breaker, they had concerns that

9048-629: The viaduct with new micro piles. Three bored piles were removed for the tunnelling works. 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. A criminal inquiry found

9152-482: The work carried out by independent consultants. Under the Safety Performance Scheme, contractors are now offered incentives or penalties and are required to maintain a Risk Register that identifies all hazards. The contractors and LTA meet every six months over safety performances, and identify and mitigate potential risks during the progress of works. These new regulations were reported to have driven up

9256-550: The worksite due to incorrect analysis of soil conditions by the contractors, leading to more pressure on the retaining walls. In April, the LTA had said the collapse happened without warning but the LTA had already found flaws in Nishimatsu–Lum Chang's design in October 2001: the contractor used a design-software simulator with incorrect parameters. An alternative design had been proposed in consultation with an NTU professor but

9360-402: Was also alerted to other ground movements, Nishimatsu addressed these cracks by applying cement patches, and no further corrective actions were taken because the buildings did not suffer any structural damage. According to a system analyst from Monosys, the project's subcontractor, the strain-detecting sensors recorded readings that were still below trigger values at 3 pm. These readings were

9464-428: Was built using the top-down method while the 1.8 km (1.1 miles) of tunnels were bored, minimising their impact on the environment. Retaining walls for the new station site were 1.5 m (4.9 ft) thick and entrenched 60 m (200 ft) underground – twice the previous depth. To reduce ground movement, the walls would be embedded into hard layers of soil. To ensure stability and prevent movement of

9568-417: Was caused by hardware problems, sending errant signals from a "rogue" train, PV46. On 30 September 2023, due to the discovery of a crack on the rails near Promenade station, delays of about 30 minutes occurred between Dhoby Ghaut, Marina Bay, and Stadium stations for 14 hours. On 17 September 2024, at 5.50pm, a power outage on the Circle Line disrupted services along the entire line, with 11 trains stalled in

9672-471: 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

9776-454: Was completed on 17 April 2010 and the next stage to HarbourFront opened on 8 October 2011. A two-station extension to Marina Bay station was opened on 14 January 2012. The last stage of the line from HarbourFront to Marina Bay with stations at Keppel , Cantonment , and Prince Edward Road will be completed in 2026, completing the loop. It is the second line in Singapore after the North East Line to be completely automated and driverless and

9880-423: Was consulting with the LTA on the day of the collapse after being alerted of the failing struts. To meet deadlines, Chikushi had accelerated the hacking of a wall that led to the removal of support beams in the excavation, and approved the grouting method that left gaps under some cables running across the site. He did not consider how these methods would cause problems. The final phase of the hearing, which involved

9984-616: Was in charge of the rescue team, was awarded the Pingat Pentadbiran Awam  – Emas (Public Administration Medal – Gold) and 18 other SCDF officers were awarded other State medals. Heng was posthumously honoured with the Pingat Keberanian for prioritising the safety of his colleagues over his own escape in May 2004. In 2014, three former colleagues whom Heng rescued inaugurated a memorial bench at Tampines Tree Park dedicated to

10088-423: Was informed of the deflection readings four days before the collapse, admitted his lack of respect for safety, that his initial response was "any solution adopted should not bring about claims against LTA" and that he failed to take heed of the warnings. The project manager from Nishimatsu, Yoshiaki Chikushi, also said he was unaware of the extent to which the struts supporting the construction site had buckled, and

10192-587: Was planned to have 18 stations, with a possible extension to Tanjong Pagar station. Plans for the line were confirmed and approved by the government on 12 June 1998. However, due to the high costs and lack of development in Marina South, the Chinatown branch was later removed in November 1999 and the line was reduced to 6 stations from the Dhoby Ghaut to Stadium stations. A part of the removed leg later became part of

10296-408: Was poorly designed and was weaker than it should have been, and there was a lack of monitoring and proper management of data. The COI report said the "warning signs", such as excessive wall deflections and surging inclinometer readings, were not seriously addressed, and blamed the collapse on the contractor. The people responsible were accused of indifference and laxity towards the worksite safety of

10400-513: Was project director of the CCL and responsible for monitoring the site's readings, faced charges under the Building Control Act. The CCL project director's trial began on 3 October 2005; he was found guilty and fined S$ 8,000 (US$ 6,000 ) on 24 November. On 28 April 2006, three senior executives from Nishimatsu were fined; the company's project director was fined S$ 120,000 (US$ 88,000 ) for his failure to take appropriate measures concerning

10504-403: Was quickly stabilised through the injection of concrete into areas that were vulnerable to movement or further collapse. Several vehicles, equipment and construction materials were retrieved using a specialised crane. The remaining equipment and materials at the site were buried under infill to avoid further collapse. Access to the collapsed site via the completed parts of the tunnel and the shaft

10608-416: Was reported that leaks and a damaged electrical cable along the Circle Line were the cause of the disruption. The disruption started at about 5.30am. Train services were gradually restored from 8am and all services were restored just before 10am. Dakota and Mountbatten stations were the last two to resume operations. Investigations were carried out, and the fault was traced back to a faulty cable beneath

10712-483: Was sealed off. Singaporean authorities dismissed terrorism and sabotage as causes of the incident. On 22 April, Singapore's Ministry of Manpower established a Committee of Inquiry (COI) to investigate the cause of the incident. Senior District Judge Richard Magnus was appointed Chairman; he was assisted by assessors Teh Cee Ing from the Nanyang Technological University (NTU) and Lau Joo Ming from

10816-465: Was the world's largest underground depot when it opened in 2009. To increase the capacity of the Circle Line, an additional 24 second-generation Alstom Metropolis trains were supplied under contract C830C , a similar in design to the first-generation trains, were delivered to Singapore from July 2014. They are also built in Shanghai , China by Alstom between 2014 and 2016. To facilitate the extension of

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