name the common serving line of bingen hauptbahnhof and saarbrücken hauptbahnhof ?
SELECT DISTINCT var_uri where brack_open dbr_Bingen_ attr_open Rhein attr_close _Hauptbahnhof dbo_servingRailwayLine var_uri sep_dot dbr_Saarbrücken_Hauptbahnhof dbo_servingRailwayLine var_uri brack_close