The East Coast Integrated Depot, incorporating three MRT depots as well as one for buses, will save $2 billion in taxpayer money, said Minister for Transport Khaw Boon Wan.
In a Facebook post yesterday, he said the cost of construction of the depot is about $3.2 billion, 40 per cent less than what it would have cost had the four depots been built separately.
He also noted that building the depots separately would have used up an additional 44ha of land, twice the land size of Changi Airport's Terminal 4.
The new depot complex, scheduled to be completed in 2024, will replace the existing Changi depot for the East-West Line. It will include depots for the East-West and Downtown MRT lines, as well as the upcoming Thomson-East Coast Line.
The Land Transport Authority (LTA) first revealed plans for the depot - said to be the first such facility of its kind - in 2013.
In 2016, South Korean firm GS Engineering & Construction won a $1.99 billion contract to build the East Coast Integrated Depot. Other contracts, such as those for electrical and mechanical works, make up the rest of the $3.2 billion cost.
GS Engineering & Construction was also involved in the building of the Gali Batu Depot in Woodlands Road, as well as the Fort Canning and Tampines East stations, all on the Downtown Line.
The train depot complex will comprise three levels, with the Downtown Line depot located underground, the Thomson-East Coast Line depot at ground level and the depot for the East-West Line above that.
The three train depots have been designed to operate independently of one another, said an LTA spokesman. "Careful planning has been done for them to share the same layout so that MRT lines with different numbers of train cars can be stacked on top of one another," the LTA added, noting that the depot can house around 220 trains.
A bus depot, which can house 760 buses, will be located next to the MRT depots.
Mr Khaw credited LTA rail engineer Adrian Teo and his project team for the depot.
Mr Khaw, who is also Coordinating Minister for Infrastructure, said the team succeeded in coming up with an "out-of-the-box creative solution" that was "future-proof, safe and also cost effective".
"The East Coast Integrated Depot was the team's innovative answer to our growing infrastructure needs in land-scarce Singapore," he said.
In his Budget speech on Monday, Finance Minister Heng Swee Keat also cited the depot as an example of how government agencies were looking to become "more efficient and effective".
