any metro trains in the city of Xian

Well, there is metro system in the city indeed, but only line 1 and line 2 is in operation now. Let me know what attractions you would like to visit so that I can tell you if they will lead you there.

Anyway, for the most famous terracortta warriors, it cannot take u there directly. You are suggested to take local public bus to XA Railway Station, on the east square of which, you can take tourist bus line 5 (no. 306), 914 or 915 to the museum directly.