Downtown Line 3 taking shape as Singapore River diversion comes to completion

The Singapore River and its surroundings as seen before the diversion works began (above left), in November 2012 (top left) and this year (right). The process involved demolishing parts of the old river embankment while building a series of dams, har
The Singapore River and its surroundings as seen before the diversion works began (above left), in November 2012 (top left) and this year (right). The process involved demolishing parts of the old river embankment while building a series of dams, hardening the soil for tunnelling, and excavating a new canal 40m wide, 100m long and 7m deep.PHOTOS: LAND TRANSPORT AUTHORITY
The Singapore River and its surroundings as seen before the diversion works began (above left), in November 2012 (top left) and this year (right). The process involved demolishing parts of the old river embankment while building a series of dams, har
The Singapore River and its surroundings as seen before the diversion works began (above left), in November 2012 (top left) and this year (right). The process involved demolishing parts of the old river embankment while building a series of dams, hardening the soil for tunnelling, and excavating a new canal 40m wide, 100m long and 7m deep.PHOTOS: LAND TRANSPORT AUTHORITY
The Singapore River and its surroundings as seen before the diversion works began (above left), in November 2012 (top left) and this year (right). The process involved demolishing parts of the old river embankment while building a series of dams, har
The Singapore River and its surroundings as seen before the diversion works began (above left), in November 2012 (top left) and this year (right). The process involved demolishing parts of the old river embankment while building a series of dams, hardening the soil for tunnelling, and excavating a new canal 40m wide, 100m long and 7m deep.PHOTOS: LAND TRANSPORT AUTHORITY

Toughest part of construction, which involves underwater tunnelling, is almost over

SINGAPORE - The most challenging portion of building the new MRT Downtown Line 3, which involved the diversion of the Singapore River - not once but twice - is almost over.

The Land Transport Authority (LTA) said tunnelling under the river between the Chinatown and Bencoolen stations will be completed by year end. Work to reinstate the original flow of the waterway should finish by next year.

Downtown Line 3 will link Chinatown to Changi by 2017.

The task of diverting the river began over two years ago, when a part of it near Riverside Point was rechannelled. This involved demolishing parts of the old river embankment while building a series of dams, hardening the soil for tunnelling, and excavating a new canal 40m wide, 100m long and 7m deep. The redirected river came within half a car's length of the ceiling of the Central Expressway (CTE) tunnel nearby.

Asked if this caused any sleepless nights, LTA project director Chang Kin Boon said: "We are engineers. This is what we do."

"We looked at all the risks, from start to end. And every part of the project was well executed."

Mr Chang said none of the 200 monitors installed in the CTE to detect structural movements had triggered an alarm. The unusual construction method was necessary because the proximity of the CTE ruled out other methods.

The river had to be reinstated to its original path as a plot on its west bank - through which the redirected river flowed - was set for redevelopment. "It was a very tedious process," Mr Chang said. "But I think it's worth it."

Downtown Line 3, which connects towns like Kallang Bahru, Aljunied, Bedok and Tampines, is part of an ambitious race to double the rail network to 360km by 2030 after a building lull in the early noughties. Downtown Line 3 tunnelling is close to 90 per cent done, while stations are close to 75 per cent completed.

Downtown Line 2, linking Bukit Panjang to Rochor, is slated for completion by the first quarter of 2016. Civil works are completed, and electrical and mechanical works have commenced.

Elsewhere, the Tuas West Extension, which brings the East-West line close to the Second Link, is fast taking shape. It will be Singapore's first two-tier viaduct when it is up by 2016, with trains on the upper deck, and road vehicles on the lower.

Civil works have also commenced on the northern stretch of the Thomson-East Coast Line linking Woodlands in the north to Marina Bay in the south, before turning east towards Sungei Bedok.

It will open in stages from 2019 to 2024, and will eventually link up to Johor Baru. Construction for the East Coast stretch of the line will start in 2016.

Other lines such as the 50km Cross Island Line (linking Changi to Jurong), 20km Jurong Region Line to serve Choa Chu Kang, Boon Lay and Tengah, and Circle Line 6 (which will make the Circle Line a complete loop) are in the advanced stages of planning.

Mr Derek McCully, managing director of Aston Martin Lagonda (SEA), said he is looking forward to the completion of the Tuas West Extension. "One of the stations is barely 50m from our facility," he said, referring to his showroom-cum-workshop in Tuas Basin Link. "It will improve accessibility and it'd be great for our employees."

The next new line to open is the North-South Line extension to Marina South. It will bring Singapore's oldest line farther south to Marina South Pier, and should open by next month.

christan@sph.com.sg