Circle Line

The Circle Line: Going Places Faster

Building the Circle Line (CCL) was a feat that required innovations in design, engineering and construction. It took place in challenging soil conditions, a maze of underground structures, and under a densely packed surface of roads, expressways and buildings.

Proposals for the line began in the 1990s, and plans for the CCL evolved to:

cater to growing public transport demand,
distribute commuter traffic away from busy interchanges, and
create a greater number of connections and faster journeys.

As its name suggests, the 30-station CCL is a circular rail line linking the North-South, East-West and North East Lines to the city.

Estimated travel time between Bishan and Changi Airport

By intersecting existing train lines across key interchanges, and bypassing the busy City Hall and Raffles Place MRT stations, the CCL shortens trips between the north, east and west of Singapore, making travel more convenient.

Train and Station Features

Train and Station Features

Length of rail
35km

Number of stations
30

Number of interchanges
11

CCL is Singapore’s first medium-capacity line and will become a complete circle in 2026 with the opening of CCL6, which comprises three stations connecting HarbourFront to Marina Bay.

It is Singapore’s second MRT train line after the North East Line to be completely automated and driverless.

Each train on the CCL is 70m long (as long as 2.5 basketball courts) and weighs around 118 tonnes, or the equivalent of 15 adult Asian elephants. At its maximum capacity, each train can carry up to 931 passengers.

The rolling stock of the train is Alstom Metropolis C830 & Alstom Metropolis C830C. It has a maximum design speed of 80 km/hour. The third-generation of rolling stock, Alstom Metropolis C851E will enter service in 2026 with the opening of CCL6.

Design and Architecture

Design and Architecture

In 2000, to draw in good quality and innovative designs for Bras Basah and Stadium MRT stations on the CCL, LTA and Singapore Institute of Architects organised the Marina Line International Architectural Design Competition. Renowned local architectural firm, WOHA, won the competition for both stations.

The CCL features a series of art works that enhance commuting experience.

Bras Basah MRT station lies in the heart of the Historic Civic District in Singapore. As such, one of the design requirements during the international design competition was that the station should not block the Singapore Art Museum.

The winning underground design from WOHA retains the visual connection to the external environment, with a station roof that doubles up as a reflecting pool and skylight. This brings daylight into the deep station while creating a landscaped water garden for the museum on the surface. When viewed from the park, the pool mirrors the museum against the blue sky; from the station concourse, sunlight and shadows create a dynamic light show.

Located next to the National Stadium, station architects WOHA had to address the scale of the large buildings in the vicinity and accommodate for surge crowds during events at the Singapore Indoor Stadium and the National Stadium. An open-air concourse and plaza space at ground-level as well as fare gates at opposite ends of the station offer plenty of space for crowds to snake into queues. The form of the station was inspired by the dynamic flux of human traffic and inflected by the sweeping curves of the stadium. Contrasting a linear element against a curved one, the station design was conceived as a dramatic silver canyon that is breathtaking in scale. As one takes the downward escalators to the platform, the curved wall closes in to reveal a slit of daylight along the entire platform.

One of the exits at Marina Bay MRT station

Located in a public park, Marina Bay MRT station is an integral part of the Marina Bay development and an interchange station for the North-South and Circle lines. The station’s design integrates it into the park through landscaping. A translucent canopy allows natural light to penetrate deep into the underground concourse. To minimise the visual impact of the station on the surrounding park, only elements such as the lift, entrance glazed enclosure, lightweight canopy and reflective pool are visible on the ground level. As one exits from the station, commuters are greeted with a panoramic view of the landscape.

Construction Challenges

Construction Challenges

Construction began in 2002, and the line came into operation in phases from 2009. The story of the CCL’s long journey is marked by hard work, tenacity and innovation to overcome numerous challenges, such as:

Varying soil conditions, which posed safety and structural issues at both Promenade and Nicoll Highway MRT stations. Special techniques were used to tunnel in these areas as well as under the Kallang Basin. In the Mountbatten area, hard ground made it extra difficult to extract some 500 reinforced concrete and steel foundation structures (called piles) that had been placed as supportive structures, and explosives had to be used to break through the rock. Some of the special techniques (PDF) used include top-down construction (PDF, 648kb), and building a continuous bored pile wall (PDF, 475kb), a secant pile wall, and diaphragm (PDF, 371kb) and sheet pile walls (PDF, 372kb) (internal) (PDF, 243kb).
Tunnelling through a maze of existing tunnels and cables. The CCL tunnels run close to the Kallang-Paya Lebar Expressway tunnel, the Deep Tunnel Sewerage System, and cable tunnels near the Upper Paya Lebar/Airport Road junction, so extreme precision had to be exercised in building the CCL’s tunnels. The CCL also weaves through built-up areas, such as Dhoby Ghaut, the dense residential neighbourhoods of Bishan and Serangoon, as well as existing underground train lines and stations. In some cases, laborious manual digging had to be done to prevent disruption to commuters and ongoing train operations.