One thing is quite certain here is that for the SG side, the RTS connecting station will be adjacent to the Woodlands North MRT station, located next to the Republic Poly, which is also the last station on the Thomson Line.
This line and station are all underground.
If the RTS is going ahead, the connecting station will be built adjacent to it.
However, for the connecting station, which has to incorporate the CIQ can be also underground or above ground if they decide to built the line above the Straits. (imagine Paya Lebar interchange station)
If the line runs under the Straits and the first station is at Bukit Chagar, then there might be a bit of problem here.
With the PC development underway, a possible route will be coming from SG towards the front of MCS Cyberport building and run parallel or along Jln Lingkaran Dalam then swing westwards towards Bukit Chagar.
But imagine the line running under the Straits and emerging on JB side at Bukit Chagar, it will be a very steep climb upwards.
Even if the Station is 3 storey deep at Bukit Chagar, the line gradient will be as steep if not steeper than the current road up the CIQ in JB which is technically impossible for train.
And if the line runs above the Straits, then the gradient will be a lot gentler but the noise will be a nuisance for the PC residents!