AFTER LNDG AND EXITING THE RWY; AN ACR FLC RECEIVED INSTRUCTIONS TO TURN L ON A TXWY WHICH; UNKNOWN TO THEM; THEY HAD ALREADY PASSED. WHEN THE FLC TURNED L AS INSTRUCTED; THEY DISCOVERED THAT THEY WERE ON A RWY INSTEAD.

Narrative

AFTER LNDG ON RWY 36L; WE CLRED THE RWY AT TXWY 'WL' TO HOLD SHORT OF RWY 36R; AS PER TWR INSTRUCTIONS. AFTER PASSING ALL TXWY INTXNS AND APCHING RWY 36R TO HOLD SHORT; TWR INSTRUCTED US TO TURN L ON TXWY 'E' AND HOLD SHORT OF TXWY 'Y.' I INTERPRETED THE INSTRUCTION TO CONTINUE TAXIING; SINCE I SAW THE SIGN MARKED TXWY 'F;' THINKING THAT THE NEXT TXWY MUST BE TXWY 'E.' WE THEN REALIZED THAT ON APCHING TXWY 'F' THAT WE HAD CROSSED RWY 36R WITHOUT CLRNC. TWR THEN GAVE US INSTRUCTIONS TO PROCEED L OF TXWY 'F' HOLD SHORT OF TXWY 'Y;' WHICH WE DID WITH NO FURTHER COMPLICATIONS. IN ANALYZING WHY WE HAD CROSSED THE RWY WITHOUT CLRNC; SOME OF THE FACTORS WERE: RECEIVING AN IMPOSSIBLE INSTRUCTION TO TURN ON A TXWY THAT WE HAD PASSED (WITHOUT REALIZING IT); AND ASSUMING TXWY 'E' WAS NEXT TO TXWY 'F.' THERE WAS SOME DISTR IN ACCOMPLISHING THE AFTER LDNG CHKLIST. AT THE SAME TIME THE TWR WAS GIVING INSTRUCTIONS; THE SO ASKED ME IF I STILL WANTED THE LNDG LIGHTS ON AND THAT THE #3 ENG COULD BE SHUT DOWN IF I SO DESIRED. SUPPLEMENTAL INFO FROM ACN 324597: WHILE ON TXWY WL AND AFTER PASSING ALL TXWY INTXNS; WE SLOWED TO STOP SHORT OF RWY 36R. BEFORE WE CAME TO A STOP; THE TWR INSTRUCTED US TO TURN L ON TXWY E AND HOLD SHORT OF TXWY Y. WE PROCEEDED ON TXWY WL TOWARD WHAT WE THOUGHT WAS TXWY E AND REALIZED WE WERE XING RWY 36R. ON TXWY WL APCHING TXWY F; THE TWR TOLD US TO TURN L ON TXWY F AND HOLD SHORT OF TXWY Y. THE REST WAS NORMAL OPS. HUMAN FACTORS CONSIDERATIONS: JUST CLRING A RWY IS A VERY BUSY TIME TO RECEIVE 2 CLRNCS. WHILE TAXIING UP TO HOLD SHORT OF A RWY WE RECEIVED INSTRUCTIONS TO TURN L ON A TXWY. THE ONLY TXWYS AVAILABLE FOR US TO TURN ON WERE AHEAD ON THE OTHER SIDE OF A RWY. WX COULD HAVE BEEN A FACTOR. DUE TO IFR WX; RAIN AND FOG; THE TWR MAY NOT HAVE BEEN ABLE TO SEE THAT WE WERE ALREADY THROUGH THE INTXN THEY DIRECTED US TO TURN ON. POSSIBLE CORRECTIVE ACTIONS: SITUATIONAL AWARENESS; STANDARD RWY/TXWY MARKINGS; AND RECEIVING EXECUTABLE CLRNCS. SUPPLEMENTAL INFO FROM ACN 324450: WE LANDED ON RWY 36L DFW AND TAXIED CLR OF THE RWY. ATC GAVE INSTRUCTIONS TO TURN L ON TXWY E. THE FO READ BACK THE CLRNC AND THE CAPT (I BELIEVE) ACKNOWLEDGED. I THEN PROCEEDED TO DO MY AFTER LNDG PANEL CHK TO READY FOR ENG(S) SHUTDOWN. I COMPLETED; AND UPON TURNING FORWARD IN MY SEAT; I FOUND US XING RWY 36R. (UNAUTH?)