In addition to the enhancement works to Tanah Merah MRT station, LTA has also announced that existing MRT tracks will be extended to connect to the four-in-one depot at Changi, which will house trains from the East-West Line, Downtown Line (DTL) and the recently announced Thomson-East Coast Line (TEL), alongside a bus depot.

The four-in-one depot to be built together with the TEL by 2024, is a first in the world to integrate three train depots and one bus depot within a single site.

As the EWL, TEL and DTL train lines would run in the vicinity of the depot site, LTA optimised land usage by stacking three train depots above one another. With such integration, an area approximately the size of 60 football fields will be saved.

The DTL Depot is located underground, followed by the TEL Depot at-grade, and the EWL Depot elevated on the level above. The three train depots have been designed to operate independently of one another, though extensive planning has been conducted for them to share the same layout so that MRT lines with different number of train cars can be stacked on top of one another. The total stabling capacity of the integrated depot is around 220 trains.

Meanwhile, the bus depot is an independent three-storey structure located next to the train depots. The workshops are located on the first level while parking bays for around 550 buses are planned on the second and third levels.

Once the four-in-one depot is completed in the year 2024, LTA will start working on transferring the operations from the current Changi EWL depot to the new depot.