GA ACFT INADVERTENTLY CROSSED AN ACTIVE RWY DUE TO TAXIWAY CONFUSION.

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I RECEIVED IFR CLRNC AND TAXI INSTRUCTIONS FROM ACK TWR. I PROCEEDED TO TAXI ON THE OUTER TAXIWAY ACCORDING TO INSTRUCTIONS TO WHAT I THOUGHT WAS TO BE THE TKOF POINT; TAXIWAY ALPHA AND RWY 24. FROM ACK ATIS I KNEW THAT 33 WAS THE ACTIVE LNDG RWY AND 24 WAS THE ACTIVE TKOF RWY. AS I WAS TAXIING CLOSE TO 15/33 I WAS PAYING MORE ATTN TO WHAT WAS HAPPENING ON THAT ACFT RWY SINCE I WOULD BE XING IT. A TWIN HAD LANDED AND WAS TAXIING TOWARDS THE INNER TAXIWAY AND I COULD SEE ANOTHER ACFT OUT ON FINAL. I CROSSED THE END OF 33 ABOUT THE TIME THAT THE TWIN TURNED OFF ON THE INNER TAXIWAY AND PROCEEDED TO THE BEGINNING OF 24; WHERE I THOUGHT THAT TAXIWAY ALPHA WAS. I DID MY RUNUP AND PRETKOF CHKS AND CALLED ACK TWR. ACK TWR INSTRUCTED ME TO CALL THEM UPON ARR AT MY DEST. I ASKED IF THERE WAS A PROBLEM AND THEY SAID IT WOULD BE DISCUSSED ON THE PHONE. FINALLY I REALIZED THAT I WAS NOT AT THE INTXN OF TAXIWAY ALPHA AND RWY 24. TAXIWAY ALPHA WAS ON THE S SIDE OF 15/33. THERE WAS NO INCIDENT OR ACFT COMING ANYWHERE NEAR EACH OTHER AS A RESULT OF MY XING 15/33 WHEN I ACTUALLY WAS NOT CLRED TO DO SO. CONTRIBUTING FACTORS; PERCEPTIONS; ASSUMPTIONS: I ASSUMED THAT TAXIWAY ALPHA WAS AT THE BEGINNING OF RWY 24. I FLY INTO TETERBORO WHERE THIS IS THE CASE (TAXIWAY ALPHA INTERSECTS WITH RWY 24). I NEVER SAW THE TAXIWAY ALPHA SIGN WHICH I MUST HAVE PASSED WHEN I WAS MORE CONCERNED WITH WHAT WAS HAPPENING ON 15/33. I HAVE NOT YET BEEN BACK TO ACK BUT I AM CURIOUS WHY I MISSED THE ALPHA SIGN AND IF IT IS NOT AS VISIBLE FROM THE OUTER TAXIWAY. I ALMOST ALWAYS ASK CONFIRMATION TO CROSS A RWY BEFORE I DO SO. THE TWIN TAXIING ON 15/33 REINFORCED MY BELIEF THAT GOING ACROSS WAS OK. IF I'M NOT SURE WHERE I AM SUPPOSED TO GO ON AN ARPT I STOP AND ASK. I THOUGHT I WAS DOING THE CORRECT THING. PS: AFTER ARR AT MY DEST I CALLED ACK TWR AND HAD A FRUITFUL DISCUSSION OF MY ACTIONS WITH THE TWR CHIEF. HIS OPINION WAS THAT INADEQUATE TAXIWAY MARKINGS IN GENERAL LEAD TO ERRORS AND HE WAS QUITE SYMPATHETIC TO WHY I MADE THIS ERROR. LOOKING BACK AT THE WHOLE THING IT SHOWS THAT EVEN IF A SITUATION APPEARS NORMAL YOU CANNOT ASSUME THINGS; AND I DOUBT THAT THIS WOULD HAPPEN TO ME AGAIN. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO. FACILITY SUPVR CLAIMS THAT THEY HAVE NOT HAD ANY PROBLEMS WITH PLTS CONFUSING TAXIWAY FOR THE END TAXIWAY. HE STATED THAT THERE ARE TAXIWAY SIGNS IN THE AREA TO IDENT ALL TAXIWAYS AND RWYS; AND SUSPECTS THAT PLT WAS NOT LOOKING IN THE RIGHT DIRECTION. DOESN'T THINK THAT THERE IS A PROBLEM WITH ARPT SIGNAGE. ANALYST MENTIONED THAT THE NOAA ARPT DIAGRAM INCLUDES TAXIWAY NAMES; BUT THE COMMERCIAL CHART DOES NOT. RPTR INDICATED THAT ALL TAXIWAY SIGNS ARE ALSO LIGHTED.