A COMMUTER TURBOPROP EXITED THE RWY SHORT OF A TXWY DURING LIMITED VISIBILITY. ONLY THE S ROW OF THE TXWY LIGHTS WERE VISIBLE AND THE CAPT COULD NOT SEE ANY RWY LIGHTS. THE ACFT BECAME STUCK IN A BERM AND THE PAX HAD TO BE DEPLANED AND TRANSPORTED TO THE TERMINAL.

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I WAS CAPT OF A FLT FROM CMH TO CVG. THE ACFT WAS LANDED ON RWY 36R AT CVG BY THE FO; AND AS I ATTEMPTED TO EXIT THE RWY ON TO TXWY T6; THE ACFT ENCOUNTERED A SNOW BANK AND BECAME STUCK. THE ACFT WAS UNDER COMPLETE CTL AT ALL TIMES. THERE WERE NO INJURIES TO CREW OR PAX. THERE APPEARED TO BE NO DAMAGE TO THE ACFT. IN HINDSIGHT IT IS APPARENT THAT MY ATTEMPT TO ENTER TXWY T6 (IT IS A HIGHSPD TXWY) WAS PREMATURE. THE ENVIRONMENT AND RWY CONDITIONS AT THIS TIME WERE NOT GOOD. IT WAS DARK; IT WAS SNOWING AND RWY LIGHTING WAS NOT OPTIMAL DUE TO EXTENSIVE SNOW COVER. I BELIEVED I KNEW WHERE I WAS; BUT I WASN'T THERE. I AM QUITE FAMILIAR WITH THE ARPT; BUT THAT WAS ALSO PART OF MY MISTAKE. I RECALLED PASSING TXWY T5; A REVERSE HIGH SPD FOR RWY 36R; AND I THOUGHT TXWY T6 WAS PRACTICALLY ADJACENT TO IT; BUT IT IS NOT. THE ONLY LIGHTING I RECALL SEEING WAS THE BLUE EDGE LIGHTS OF WHAT I THOUGHT WERE TXWY T6; I DID NOT SEE ANY RWY EDGE LIGHTS AS I BEGAN MY EXIT. I ALSO FELT UNDER A PERCEIVED PRESSURE TO GET OFF THE RWY. DEPS WERE BEING DELAYED BECAUSE OF THE SNOW AND ARRIVING TFC. I ALSO BELIEVE FATIGUE PLAYED A PART. I WAS INTO MY 10TH HR ON DUTY; 5TH LEG OF THE DAY; AND 10TH LEG IN 2 DAYS. SO MY LEVEL OF ALERTNESS WAS NOT OPTIMUM. I FOLLOWED VISUAL CUES THAT WERE INCOMPLETE AND SITUATIONAL AWARENESS THAT WAS INCORRECT. CRM COULD HAVE BEEN BETTER ALSO; I SHOULD HAVE ASKED MY FO FOR HELP IN FINDING THE TXWY AND OF COURSE; HE COULD HAVE SPOKEN UP ALSO IF HE WAS UNCOMFORTABLE. HE DID; BUT IT WAS TOO LATE. SUPPLEMENTAL INFO FROM ACN 325443: AS THE LNDG AND TAXI LIGHTS BEGAN TO REFLECT OFF THE SNOW BERM CREATED BY THE PLOWING OF THE RWY (RWY EDGE); IT BECAME APPARENT TO ME THAT THE CAPT HAD MISCALCULATED THE TXWY T6 CTRLINE AND WAS COMMITTING HIMSELF TO A L TURN. WE TAXIED OFF THE RWY EDGE INTO A SNOW BERM SHORT OF TXWY T6. PAX AND CREW WERE NOT INJURED. TWR WAS ADVISED OF SIT AS WELL AS THE FLT ATTENDANT AND PAX. COMPANY MAINT CTL WAS NOTIFIED. ACFT WAS SECURED AND ENGS SHUT DOWN PER CHKLISTS. PAX WERE UNLOADED INTO A COMPANY SHUTTLE BUS AND TRANSPORTED TO TERMINAL.