COMMUTER LTT TAXIES ONTO ACTIVE RWY.

Narrative

TAXIING FOR TKOF; RWY 28; AT TRAVERSE CITY; MI. THE MAIN RWY AND PARALLEL TXWY WAS PLOWED BUT HAD ACCUMULATED ADDITIONAL SNOW. A SECOND PARALLEL TXWY (TXWY E LEADING TO 1 OF THE GA PARKING RAMPS WAS NOT PLOWED. BECAUSE OF MY FREQUENT OPS FROM THIS ARPT; I TAXIED PAST THE FIRST TXWY E THINKING IT TO BE THE 1 LEADING TO THE PARKING AREA. AS IT TURNED OUT; I WAS TAXIING PAST THE SECOND PARALLEL TXWY B. NOTICING THAT THE TXWY LIGHTS WERE WHITE; INSTEAD OF BLUE; I IMMEDIATELY HAD THE FO TO ADVISE TWR THAT WE HAD TURNED ONTO THE RWY. UP UNTIL THIS POINT THE FO WAS OCCUPIED WITH THE LOAD MANIFEST; AND HAD HIS HEAD DOWN. THE FO INSTEAD OF STATING OUR PRESENCE ON THE RWY; ASKED IF WE COULD BACK-TAXI. TWR RESPONDED THAT THERE WAS AN ACFT AHEAD OF US. HE MAY HAVE SAID THERE WAS AN ACFT IN POS FOR TKOF; BUT I DON'T REMEMBER. HOWEVER; I DID LOOK DOWN THE RWY TO SEE A KING-AIR IN POS. AT THAT POINT THE FO SAID WE WERE ON THE RWY. TWR INSTRUCTED US TO MAKE A 180 TURN TO EXIT THE RWY AND CONTINUE TO TAXI. I DON'T KNOW IF STANDARD PROCS CALL FOR A TWR CTLR TO HOLD A DEPARTING ACFT IN POS WHILE ANOTHER ACFT TAXIING MAY RUN THE CHANCE OF AN INCURSION. I KNOW THE FIELD WAS OPERATING UNDER IFR CONDITIONS BUT I DON'T BELIEVE THAT THE RWY AND TXWY LIGHTS WERE TURNED ON. THE SNOWY CONDITIONS ARE VERY COMMON; AND REDUCED VISIBILITY OPS MAY INCLUDE EXTRA VIGILANCE ON MY PART ESPECIALLY AND I'M GLAD THAT THE TWR CTLR WAS ALSO OBSERVANT WHETHER OR NOT THEY ARE REQUIRED UNDER THESE CONDITIONS. BECAUSE THE SECOND TXWY E WAS NOT PLOWED; I DID NOT SEE IT; AND KNEW TO TURN AT THE SECOND TXWY; THUS LEADING TO THE INCURSION.