C310 PLT TAXIES INTO DITCH AFTER ENCOUNTERING JETBLAST AND FOGGING WINDOWS.

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FIRST; I CARRY A SQUEEGEE; AND SQUEEGEED THE WINDSHIELD BEFORE THE START SEQUENCE. CLRED TO TAXI; I TAXIED. I WAS CHANGING THE GND FREQ IN MY #2 RADIO (BECAUSE #1 RADIO WAS BREAKING UP A LITTLE) AND PUTTING ATIS FREQ INTO #1; BUT I WAS HIT BY FAIRLY STRONG JETBLAST FROM THE LINE OF TFC HOLDING; WHICH CHANGED MY FORWARD DIRECTION AND ALSO HEAVILY REFOGGED MY PLEXIGLAS WINDSCREEN. I CONTINUED MY TAXI THOUGH; BELIEVING I WAS STILL CORRECTLY ON COURSE. THE AIRPLANE WAS NOW POINTED DIAGONALLY ALONG THE TXWY. AT THIS POINT; I KNEW THAT SOMETHING WAS AMISS; BUT I MISTAKENLY THOUGHT THAT I WAS R OF COURSE AND TURNED SOMEWHAT L. THEN I TURNED AGAIN TO THE R BTWN 2 SETS OF BLUE TXWY LIGHTS; BUT THE PROB HERE WAS; I WAS ON ANOTHER PART OF THE TXWYS THAN WHERE I BELIEVED I WAS; AND INSTEAD OF TURNING DOWN THE TXWY; I TURNED BTWN THEM AND DROPPED THE AIRPLANE INTO THE DITCH. CONTRIBUTING FACTORS: 1) THE JETBLAST FROM THE WAITING HVY METAL TFC. A) THIS TURNED MY AIRPLANE'S FORWARD MOVEMENT; AND IN LOW WINDSHIELD VISIBILITY B) CAUSED HVY FOG TO FORM ON THE WINDSCREEN. 2) I WAS BUSY IN THE COCKPIT A BIT CHANGING RADIO FREQS TO THE BETTER RADIO WHILE FORCES OUTSIDE WERE CHANGING MY COURSE. 3) MY BELIEVING; IN LOW VISIBILITY; THAT I WAS SOMEWHERE WHERE I WAS NOT; AND SOME OVERCONFIDENCE WAS FACTOR; AS I HAVE FLOWN THIS RTE 4 TIMES PER WK; 2 ROUND TRIPS PER NIGHT FOR 14 MONTHS AND I'VE BEEN ALONG THESE TXWYS OVER 1000 TIMES. FIXES MIGHT BE: 1) GREEN CTRLINE TXWY LIGHTS (OR EVEN REFLECTORS) ALONG THE DIAGONAL TXWY. THIS PARTICULAR TXWY IS DIFFICULT TO DISTINGUISH EVEN ON A CLR NIGHT AND A CLR WINDSHIELD THIS DIRECTION BECAUSE OF THE HIGH GLARE FACTOR FROM LIGHTS TO THE N SIDE OF RWY.