AN UNFAMILIAR TO THE ARPT; C172 PVT PLT INADVERTENTLY TAXIED PAST THE RWY HOLD SHORT LINE RESULTING IN A RWY INCURSION.

Narrative

AFTER LNDG ON RWY 19 AT GMU; CTLR ASKED WHERE I WAS GOING ON FIELD. I RESPONDED WITH; 'TO WHATEVER FBO YOU HAVE.' HE RESPONDED BY SAYING THEY HAD 2 -- 1 ON THE L; AND 1 ON THE R.' I STATED I WANTED THE ONE ON THE R. HE TOLD ME TO TURN R AT NEXT TXWY. I TURNED R AT TXWY G. I MISSED THE TURN DOWN TXWY H WHILE TRYING TO COMPREHEND AN UNINTELLIGIBLE INSTRUCTION FROM THE CTLR. CTLR THEN INSTRUCTED ME TO TURN R AT NEXT TXWY. THE NEXT TXWY TURNED OUT TO BE RWY 10/28 (I WAS PAST THAT TXWY (TXWY A) BEFORE THE TURN INSTRUCTION). CTLR ISSUED AN INSTRUCTION TO STOP IMMEDIATELY. ALTHOUGH I NEVER WAS ON THE WY; I CLRLY SHOULDN'T HAVE TAXIED AS FAR AS I DID. CTLR THEN CLRED ME TO CONTINUE DOWN RWY TO NEXT TXWY. CONTRIBUTING FACTORS: UNFAMILIARITY WITH ARPT. THE MISUNDERSTOOD INSTRUCTION TURNED OUT TO BE A COMMENT ABOUT INDECISION ON MY PART. I AM STILL BAFFLED BY THE COMMENT. ALTHOUGH IT WAS VERY APPARENT I WAS UNFAMILIAR WITH THE ARPT; THE CTLR INITIALLY WAS NOT GIVING PROGRESSIVE TAXI INSTRUCTIONS UNTIL I MISSED THE TURNOFF. I SHOULD HAVE SPECIFICALLY REQUESTED A PROGRESSIVE TAXI.