These stations are Napier, Maxwell, Shenton Way and Marina Bay which will be stacked stations where the running tunnels are directly on top of each other instead of side-by-side as in island platform stations. As such, the platforms will be located on one side of the train as well. Here's an image of the tunnel set up at Marina Bay station.
|B1 - Circle Line extension|
B2 - North South Line tunnels
B3 - Transfer linkway and subway to new TSL entrance
B4 - Thomson Line southbound tunnel
B5 - Thomson Line northbound tunnel