The whole train setup is so inefficient. Even before the opening of the the mid-field concourse, why would T2-T1-Gate40/60 requires a switch of train, despite the three being in the straight line?

And what makes most sense is a circular track (or one with a dead-end reverse cross-over track), so trains can operate in a continuous loop at much higher frequency. All it requires is to have one or two staff to make sure all departure passengers get off at the 200 gates; and all arrival passengers get off at T1 arrivals immigration.