Circle Line

The Circle Line (CCL) is Singapore's fourth (Mass Rapid Transit) MRT lines. This underground line is 35.7 kilometres (22.2 mi) long with 31 stations (excluding Bukit Brown) and is fully automatically operated. It takes about one hour to travel from one end to the other. The line is coloured  orange  on the rail map. It is maintained by SMRT .

As the name implies, the line is an orbital circle route linking all radial routes leading to the city. It also covers many parts of the Central Area. From Promenade, the line branches with one branch terminating at Dhoby Ghaut and the other terminating at Marina Bay. Transfers to the North South Line are provided at Bishan, Dhoby Ghaut and Marina Bay, East West Line at Paya Lebar and Buona Vista, and North East Line at Dhoby Ghaut, Serangoon and HarbourFront. The Downtown Line will interchange with the Circle Line at Bayfront, Promenade, Botanic Gardens and MacPherson and the future Thomson Line will interchange with the Circle Line at Caldecott and Marina Bay.

The Circle Line is the first medium capacity line in Singapore. As a medium capacity line, each Circle Line train has only three cars instead of the six-car configuration as seen on current MRT lines. Half a million people are expected to use the Circle Line each day. The line reduces travelling time for commuters by allowing them to shorten trips between north to east or north to west and vice versa, bypassing busy interchange like City Hall and Raffles Place.

History
Plans for the Circle Line date back to the 1980s. The then Minister for Communications and Information, Dr Yeo Ning Hong stated that such a system "would be feasible when the population reaches four million."

In the 1990s, the Circle Line was first known as the Marina Line. The Marina Line was initially planned as a 12-station underground line, starting from Chinatown and Dhoby Ghaut via the National Stadium to either Kallang or Paya Lebar station. However, the Chinatown leg was later truncated and was reduced to 6 stations up to Stadium station. On the other hand, a further extension towards Upper Paya Lebar was added. Eventually, the Marina Line ended up as an inner circular line. Stations in Circle Line that were a part of the original Marina Line plans include Dhoby Ghaut, Bras Basah, Esplanade, Promenade, Nicoll Highway and Stadium. Also, the part of the Marina Line from Chinatown to Promenade is now part of the Downtown Line.

Originally scheduled to be opened from 2006 and fully opened in 2010, with an estimated cost of S$6.7 billion, the Nicoll Highway collapse caused the construction of the Circle Line to be delayed to 2009, with full opening by 2011 (excluding the Marina Bay Extension), at an escalated cost of nearly S$10 billion. Due to the re-alignment of the Nicoll Highway Station to a new location, the station is only two-thirds the size of the original plan before the collapse, and located 100 metres (330 ft) away from the highway collapse site. The decision was also made to open both Caldecott, and Haw Par Villa stations (previously Thomson and West Coast), initially planned as shell stations, together with the whole line, leaving only Bukit Brown Station closed.

Stage 3, a 5 kilometres (3.1 mi) five-station segment stretching from Bartley to Marymount, was the first section of the line opened, on May 28, 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 August 17, 2009. Stages 1 and 2 started operations on April 17, 2010; Stages 4 and 5 on October 8, 2011. and the final Circle Line Extension on January 14, 2012.

On 17 January 2013, the Land Transport Authority announced 'Circle Line Stage 6' which will close the circle, running between Marina Bay and HarbourFront via Keppel. It will be a 4 km extension and is planned to be completed by 2025.

Nicoll Highway collapse
On 20 April 2004, a section of the tunnel being built for the Circle Line collapsed, apparently when a retaining wall used in the tunnel's construction gave way. This occurred near what was planned to become the Nicoll Highway Station on the Circle line, not far from the Merdeka Bridge. The accident left a collapse zone 150 metres (490 ft) wide, 100 metres (330 ft) long, and 30 metres (98 ft) deep. Four workers were killed, with three more injured.

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.

As a result of this accident, the first phase of the Circle Line, previously scheduled to open in 2008, was completed in 2010 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 had 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.

Other incidents
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 metres (23 ft) stretch of two lanes sank about 20 centimetres (7.9 in), close to the junction of Telok Blangah Road and Alexandra Road in the evening, resulting in a halting of tunnelling works.

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