Downtown Line

The Downtown Line (DTL) is the fifth (Mass Rapid Transit) MRT lines in Singapore. It opened on 22 December 2013 for Stage 1, and due to be opened in 2016 and 2017 for Stage 2 and 3 respectively. When fully completed, the line will be about 42 km (26 mi) long with 34 stations and will serve about half a million commuters daily, making it the longest underground and driverless MRT line in Singapore. Travelling from one end to the other will take about 65 minutes. The line is coloured  blue  in the rail map. It is maintained by SBS Transit  .

Overview
The line will connect the North-Western and Central-Eastern regions to the new downtown of Singapore. Transfers to this line from the North East Line will be available at Chinatown and Little India, the North South Line at Newton, the East West Line at Bugis, Tampines and Expo, the Circle Line at MacPherson, Bayfront, Promenade and Botanic Gardens and Bukit Panjang LRT at Bukit Panjang. This line is the third in Singapore to be entirely underground (apart from the Gali Batu Depot). Once fully completed, this line will also be the longest automated rapid transit line, surpassing the record set by the Circle Line.

History
On 14 June 2005, the Land Transport Authority (LTA) announced that it would construct the (then known as) Downtown Extension of the Circle Line, to serve the Downtown at Marina Bay (DTMB) area, where an integrated resort (Marina Bay Sands) and Singapore's second botanical garden (Gardens by the Bay) will be located. The 3.4-kilometre fully underground line was estimated to cost S$1.4 billion. Construction of the extension was slated to begin in 2007. Bayfront and Marina Bay stations effectively opened on 14 January 2012.

On 27 April 2007, it was announced that Stage 1 of the line will connect Promenade with Bugis. As such, the former Downtown Extension of the Circle Line became known as the Downtown Line Stage 1, a 4.3 km 6 station segment running fully underground from Chinatown on the North East Line to Bugis on the East West Line, due to be operational in 2013, a year later than originally planned. Three new stations will be constructed underground, linking Bugis on the East West Line, Promenade on the Circle Line and Chinatown on the North East Line. Two stations, Bayfront and Downtown, will be built to serve the DTMB area. Another station, Telok Ayer, will be built along Cross Street near the Chinatown area. During this period of time, the line was designated  brown .

In its preliminary plans, Stage 2 of the Downtown Line was called the Bukit Timah Line, supposedly a 20-kilometre line that would connect the new downtown with the Bukit Panjang, Upper Bukit Timah and the Bukit Timah corridor. It was to intersect the Circle Line and all other current lines along the way. It was expected to alleviate the heavy traffic along Bukit Timah, Dunearn Road and Upper Bukit Timah after completion. Provisions were made at Promenade which would have been the line's southern interchange with the Circle Line. Stage 2 of the Downtown Line will be 16.6 km long, consisting twelve stations, including three interchange stations, and is scheduled to be completed by 2016. On 15 July 2008, the LTA announced the exact location, alignment and tentative name of the twelve stations to be built. Commencement of construction for Stage 2 began on 3 July 2009 with a groundbreaking ceremony at Beauty World Station.

In its preliminary plans, Stage 3 of the Downtown Line was part of the Eastern Region Line, a 40-kilometre rectangular loop that would have complemented the existing East West Line and enhance inter- and intra-town travelling in the eastern region. It would have looped around the Jalan Besar and East Coast areas, intersecting the Circle Line and other current lines along the way, benefiting residents in Tampines, Bedok, Marine Parade, MacPherson and Kaki Bukit. Stage 3 now only comprises the northern segment of the original plan, from Chinatown to Expo. Provisions were made at Chinatown, which would have been the line's western interchange with the North East Line and the Downtown Extension. The northern segment of the loop was to be constructed first, passing through Jalan Besar area and eastwards to parts of Bedok, Tampines and Expo Station to serve the Singapore University of Technology and Design (SUTD) next to Upper Changi and Singapore Expo which will move there when the new campus is completed in 2018. Being 21 km-long, the sixteen stations would have been completed by 2018. In 2008, the government decided to accelerate the sector's opening to 2016. Station locations and their working names for Stage 3 were officially announced on 20 August 2010. At the same time, the then Transport Minister, Mr Raymond Lim also announced a delay of the completion of Stage 3 by a year to 2017 to accommodate the construction of an additional station at Jalan Besar. Similar to Stage 2, preliminary work by the LTA had begun. The finalised names for the Stage 3 stations were announced on 19 August 2011.

A new MRT depot, the Gali Batu Depot, is built at part of the former Kwong Hou Sua Teochew Cemetery off Woodlands Road.

On 29 August 2011, the LTA appointed SBS Transit (SBS Transit DTL Pte Ltd) as the operator of the Downtown Line, subsequently changing the line colour to  blue .

The 30 October 2012 edition of The Straits Times reported that the final costs of building the line may reach an estimated S$20.7 billion, up more than 70% from an initial estimation of S$12 billion.

On 17 January 2013, Land Transport Authority announced 'Downtown Line Extension' which will run from Expo and through East Coast area. It is to be completed by 2025. On 24 June 2013, LTA announced that work has stopped on the King Albert Park, Sixth Avenue and Tan Kah Kee stations, after Alpine Bau GmbH, the previous main contractor, filed for insolvency on June 19 and it will take some three to six months for new contractors to resume work on three stations on the upcoming Downtown Line Stage 2 (DTL2).

On 29 August 2013, LTA announced that it has appointed McConnell Dowell South East Asia (SEA) Private Limited and SK E&C (Singapore) to complete the work on the three stations. As a result of the delay, the completion of Downtown Line Stage 2 has been pushed back from December 2015 to the middle of 2016.

On 7 October 2013, Transport Minister Lui Tuck Yew announced at the opening ceremony of the inaugural Singapore International Transport Congress and Exhibition, that Downtown Line Stage 1 will open on 22 December 2013.

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.

Marina Boulevard sinkhole incident
Marina Boulevard had to be temporarily closed and traffic was diverted on the morning of June 18, 2008 after soil on a construction site next to the road sank. Urban Redevelopment Authority said the hole measured 5 metres wide and was 2.5 metres deep. It sank at about 9:10 am. This caused a hole next to the Marina Boulevard slip road leading towards East Coast Parkway. URA said the soil subsidence is located within the construction site where construction works for the common services tunnel is being carried out. No one was injured. About 25m of the rightmost two lanes on Bukit Timah Road has been closed off to traffic after a nearby drain embankment caved in on 17 January 2012 in the course of tunnelling works for the Downtown Line. LTA said that its engineers found a 14m precast segment of the Bukit Timah canal wall near the junction of Bukit Timah Road and Clementi Road dislodged, and some gaps in the ground were formed around that segment of the canal. It then stopped its tunnelling works to ensure safety and has begun to inject cement to stabilise the ground.

Evans Road casualty incident
On 11 March 2012, a worker was killed at a site between the Botanic Gardens and Stevens station after a concrete slab fell on him. 35-year-old Masud Al Mamun was operating an excavator deep in the ground when the slab fell on him. Rescuers had to use a breaking tool kit to break a portion of the concrete slab. It took nearly five hours to reach the man lying motionless on the ground. This is the first casualty case in the construction of the Downtown Line.

Bugis casualty incident
On 18 July 2012, two Chinese workers died after a temporary scaffolding, about four metres high, used for the construction of the new Downtown Line Bugis station subway link roof slab gave way. The incident happened at about 6:50 am. The eight other injured workers who were working on top of the structure, were sent to the nearby Raffles Hospital before rescuers arrived. They had minor injuries and five of them have since been discharged. Of the remaining three workers who were warded, one suffered from abdominal and chest injuries, while another suffered a back injury and the last had a finger injury. Seven of the injured are from Bangladesh while the eighth is from China. The Ministry of Manpower(MOM) has ordered all construction work to stop, while the Building and Construction Authority (BCA) has revoked the construction permit for the site while investigations are underway. MOM said that based on preliminary information gathered, workers were pouring concrete, also known as the casting process, into the formwork when the structure supporting the formwork collapsed. The formwork, located between the new and old sections of the station, was part of the structure being built to form the underground linkway, which is about three to four metres deep. The area affected is localised, measuring about five metres by 10 metres and the entire station is about 7,500 square metres. The Land Transport Authority said the station structure is substantially complete and structurally sound, and that the incident posed no risk to surrounding developments and the public.

On 22 August 2013, the main and sub-contractor Soletanche Bachy and Koh Brothers at the construction site were charged in court over the collapse. The two companies were said to have failed to take measures to ensure that the workplace was safe and without risks to health to every person within the premises on 18 July 2012.

Woodlands Road sinkhole incident
Excavation works for the Downtown Line 2 caused a massive sinkhole on Woodlands Road on 16 March 2013. The construction destabilised the soil, which ruptured an underground water pipe. The rupture which was as wide as one of the road's lanes, appeared near West View Primary School, next to where construction work for Downtown Line 2 is being carried out.