C172 PLT READS BACK TAXI CLRNC INCLUDING INSTRUCTION TO USE A RWY FOR THAT PURPOSE. ATCT GND CTLR FAILS TO CORRECT HIM AND A CONTESTED RWY INCURSION RESULTS.

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THE TAXI CLRNC GIVEN TO ME BY THE GND CTLR WAS INCONCISE AND LACKED STANDARD PHRASEOLOGY. MY INTERP OF THE CLRNC WAS TO USE AN ACTIVE RWY AS A RTE OF TAXI TO MY DEST. I THOUGHT THIS TO BE ESPECIALLY STRANGE BECAUSE MY ARPT DIAGRAM DISPLAYED A SHORTER AND PROBABLY SAFER RTE FOR THIS. I DID NOT; HOWEVER; VOICE THIS CONCERN TO THE GND CTLR. INSTEAD; I READ BACK THE CLRNC CLRLY STATING THAT I WOULD BE USING THE ACTIVE RWY ON MY RTE OF TAXI. ALTHOUGH THE CTLR NEVER INSTRUCTED ME T HOLD SHORT OF OR CROSS THIS RWY FOR CONNECTION TO THE MORE EFFICIENT RTE; I WAS STILL EXPECTING THAT HE WOULD TELL ME MY READBACK WAS INCORRECT; AND ADVISE ME NOT TO USE THE RWY AS A LEG ON THE RTE. THE CTLR DID NOT CORRECT MY READBACK; BUT HE DID; HOWEVER; CORRECT MY TURN ONTO THE ACTIVE RWY; ADVISING ME TO HEAD BACK TO MY FLT SCHOOL SO I COULD GIVE HIM A CALL OVER THE PHONE; OR POSSIBLY PAY HIM A VISIT AT THE TWR. IN MY FOLLOW-UP PHONE CONVERSATION WITH THE GND CTLR; HE ACKNOWLEDGED MAINTAINING SILENCE WHEN IN QUESTION OF MY INCORRECT READBACK AND ITS POTENTIAL FOR A RWY INCURSION; AND I MADE HIM AWARE OF THE DEFICIENCIES IN HIS CLRNC. THESE EVENTS SERVE AS GREAT EXAMPLES OF THE RULE 'WHEN IN QUESTION; ASK.' I SHOULD HAVE VERIFIED THE CLRNC TO THE EXTENT OF ABSOLUTE CERTAINTY WITH THE CTLR'S DIRECTIONS; AND HE SHOULD HAVE VERIFIED MY READBACK TO THE EXTENT OF ABSOLUTE CERTAINTY WITH MY INTENTIONS.