Hello,
I'm new but I used a Junction Kit by Andi06 originally in trs06 and recently in ts12 - it has move-able switch rails. In ts12 though, it seems the levers and therefore arrows {green/red} are not in the ts12 version - you click the track area and they switch. The help-file on the wiki states you can add the levers in ts12, but the link for that is missing or broken.
The kit kuids are:
122285:79051 pack 1
122285:79052 pack 2
122285:79053 pack 3
You can find all the bits on the DLS, I typed JK in the name filter and it showed them all.
There are probably others too, but I used the old pack in TRS06 and it's all I have tried in TS12.
I hope this helps chap,
Mackers