As early as the first half of next year, commuters will be able to take an MRT train to the western tip of the island and get a panoramic view of Singapore's industrial heartland along the way.
Details have been revealed of the new MRT Tuas West Extension, which will feature Singapore's tallest viaduct at 23m above ground - almost twice the height of the average MRT viaduct. At Gul Circle, the first of the extension's four stops, the station ceiling will be 33m above ground - about the height of a 10-storey Housing Board block.
There are two reasons for the heights. First, the 7.5km, $3.5 billion extension goes over the Ayer Rajah Expressway viaduct at the Pan-Island Expressway interchange. Second, a 4.8km portion of the line is being integrated with a road viaduct, which runs below the rail line.
It will be the first twin-tier viaduct in Singapore, with the new elevated dual three-lane road designed to relieve Tuas' infamous heavy traffic load, which is set to become heavier once the port is moved there in 2030.
The structure is supported by a series of massive columns, each designed to bear 13,000 tonnes of weight. Columns at existing rail viaducts carry 5,300 tonnes of weight each.
Project director Andrew Yap said the piles for the columns go as deep as 60m into the ground.
Mr Yap, 62, a Land Transport Authority veteran who built the first MRT line in the 1980s, said most of the columns are already up and more than half of the horizontal beams are in place.
"Overall, the project is over the halfway mark," he said.
Work started in late 2011, and is slated to be completed next year. Mr Yap would not commit to a more specific time, but going by the progress so far, it could be ready by the first half.
The most challenging parts of the project have already been tackled. Mr Yap said these include diverting major utilities serving Tuas and upgrading a 1km-long drain in Tuas Road.
The MRT extension is expected to carry 100,000 commuters a day to Tuas, an area currently not well served by public transport.
The project includes a 26ha depot that can hold 60 trains. It will join depots in Changi, Bishan and Ulu Pandan that serve the East-West Line.
Mr Yap said structural provisions have been made for a Tuas South extension.
The Gul Circle station will incorporate a platform serving the Tuas South extension that accommodates a split-viaduct design. Instead of eastbound and westbound tracks facing each other across a platform, one is above the other. While this design has been employed in underground lines, Mr Yap said this will be the first time for an elevated line.
The northern end of the Tuas West Extension includes a 300m overrun track, a braking buffer that can also facilitate future extensions of the line.
