About 3.3 million passengers use the MRT everyday. The system is 199.6 km long and has 119 stations. Trains run from 5:30 am to 1:00 am every day except for the festive periods, such as Christmas Eve, New Year's Eve and Chinese New Year's Eve. A train comes every 2–3 minutes in peak hours, every 7 minutes during off-peak hours and 5–6 minutes for the weekend service. It is operated by Singapore's SMRT Corporation and SBS Transit.
There are currently 5 lines in the MRT system, where they are connected by special stops called interchanges. The lines are North South Line, East West Line, North East Line, Circle Line and Downtown Line. The Circle Line opened in four stages from 28 May 2009 to 14 January 2012. Stage 1 of Downtown Line opened on 22 December 2013 with its official opening made on 21 December 2013 by Prime Minister Lee Hsien Loong.
On 16 December 2011, the MRT network suffered what is likely to be the worst breakdown in its 24-year operating history. 'A power rail problem' made North-South Line trains suddenly lose power and stopped in darkness and without air conditioning for up to an hour accompanied only by light from mobile phones.
The MRT system only had two lines, the North South and East West Lines, for more than ten years until the opening of the North East Line in 2003. While plans for these lines, as well as those being built, were made long before, the Land Transport Authority's (LTA) proposal named ""A World Class Land Transport System"" in 1996 showed that the government wanted to greatly expand on the existing system. The plans allow for the long-term replacement of the bus network by rail-based transportation as the main way of public transportation. It called for the expansion of the 67 kilometres of track in 1995 to over 360 in the year 2030. It was expected that daily ridership in 2030 would have grown to 6.0 million from the current 1.4 million passengers.
The 43-kilometre Thomson-East Coast Line is planned to be completed by 2024 and consists of 32 stations. It will connect to the North South Line at Woodlands station, Orchard and Marina Bay, to the Circle Line at Thomson, Caldecott and Marina Bay, to the Downtown Line at Stevens and Sungei Bedok, and to the East West and North East lines at Outram Park. The first part, or stage, will open by the end of 2019.
The Thomson-East Coast Line was a result of a joining of two separate lines, the Thomson Line and the Eastern Region Line, which was announced on 15 August 2014. The Thomson Line consisted of the part from Woodlands North to Marina Bay, while the Eastern Region Line consisted of the rest of the joined line.
A new extension to the line was announced on 25 May 2019. The new extension will connect the line to Singapore Changi Airport, allowing people arriving from the airport to go to the city without changing to another train. The tracks of the East West MRT line that currently go to the airport will also be used by this extension, which means that trains on the line will go all the way to Tanah Merah station, and there will be no more East West line trains using these tracks. This extension will open by 2040.
To be opened by 2023, the 2-kilometre extension will run from Punggol through Punggol North including the new Punggol Downtown. The extension is for future residents in Punggol North to have train access to the city centre as well as other parts of Singapore.
The Downtown Line was built in three stages, with the first opening in 2013, the second in 2015, and the third in 2017. An extension to the third stage, known as Stage 3e, will open in 2024, being 2.2 kilometres long and with two more stations. On 7 March 2015, Senior Minister of Stage for Transport Janil Puthucheary said that there will be a new station called Hume, to be built between the already open stations of Hillview and Beauty World. This station will open in 2025. When Hume opens, the line will be 42 kilometres long and have 37 stations.
On 25 May 2019, the Land Transport Authority announced another extension to the second stage of the line to a new station, Sungei Kadut MRT station. This extension will open in the mid-2030s.
To be opened by 2025, the 4-kilometre extension will run from Marina Bay through Keppel, ending at HarbourFront, making the Circle Line a full continuous circle.
First proposed as a LRT line when originally announced in 2001, the Jurong Region Line is now going to be a medium capacity line. The new plan will serve West Coast, Tengah and Choa Chu Kang and Jurong. The line will open in stages from 2026.
The 50-kilometre Cross Island Line will go across the island of Singapore, passing through Tuas, Jurong, Sin Ming, Ang Mo Kio, Hougang, Punggol, Pasir Ris and Changi. The addition of the new line brings commuters with another way for east–west travel to the current East West Line. It will also connect to all the other major lines to serve as a key transfer line, adding to the role currently fulfilled by the orbital Circle Line. The first stage will open by 2029, and other stages are expected to open by 2031.
On 25 May 2019, the LTA announced two new stations to be built on the North South line. Brickland station will be built between Bukit Gombak and Choa Chu Kang, while Sungei Kadut will be built between Yew Tee and Kranji. Both stations will open in the mid-2030s.
In the LTA's Land Transport Master Plan (LTMP) 2040, there will be studies to see if a new line can be built, between Woodlands, and Greater Southern Waterfront areas. If the line is built, it will be about 30 kilometres long, and will be completed as early as 2040. The line could serve around 400,000 houses, and lower the time needed for travel to the city by up to 40 minutes.
Every station has ticket machines, restrooms (toilets), a passenger service center, which controls what is happening in the train station and has wired radio with the train operator, payphones (public phones) and access for disabled. Some of them have automated teller machines, kiosks and a bus interchange nearby.
All stations in Singapore are either elevated or underground, with the exception of Bishan. Underground stations and trains are air-conditioned and have full-height platform screen doors. Elevated stations have half-height platform screen doors.
A total of 11 types of rolling stock are used on the MRT lines. Almost all of them are powered by 750 voltage current from a third rail, except those on the North East MRT Line, which uses 1500 voltage current from overhead wires.
For the East West and North South Lines, six types of rolling stock are used. The oldest is the C151, built in 1986-89 by a collaboration between Kawasaki Heavy Industries and three sub-companies, Kinki Sharyo, Nippon Sharyo and Tokyu Car Corp. 66 trainsets are in operation, which were upgraded between 2006 and 2008. 19 more C651s were purchased in 1994 from Siemens AG, followed by 21 more C751B sets, built in 1999-2000 by Kawasaki Heavy Industries and Nippon Sharyo. Two companies, Kawasaki Heavy Industries and CSR Sifang, have collaborated to build 3 types of rolling stock. The fourth rolling stock in operation is the C151A. They were built between 2010 and 2014, and started operations in 2011. The next rolling stock that started operations is the C151B, which began operations on 16 April 2017. The newest rolling stock, being built between 2017 and 2018, is the C151C, and it began operations on 30 September 2018.
On the North East Line, 25 six-car trainsets of the C751A were built from 1999 to 2002 by Alstom. A further 18 trainsets, the C751C, were built by Alstom and Shanghai Electric and entered operation on 1 October 2015.
For the fourth MRT line, the Circle Line, 40 three-car trainsets of C830s were built from 2005 to 2008 and began operations in 2009. Together with the C751Cs, the same companies made 24 C830C trainsets which began operations on 26 June 2015.