GA SMT DEPARTING AIRSHOW EVENT HAD MONITORED TAPE RECORDING AND THOUGHT IT OK TO TAXI ON THE N SIDE OF RWY 9L. BEGAN TAXI FROM NE CORNER OF ARPT AND TAXIED DOWN RWY 23. APCHING RWY 9L; NORMALLY A TXWY; WAS INTERCEPTED BY VEHICLE AND TOLD TO TURN AROUND. AT THAT TIME A SMALL JET WAS DEPARTING RWY 9L. RPTR REALIZED HE SHOULD HAVE PASSED BELOW THE TWR ENRTE TO RWY 9L.

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AT THE CONCLUSION OF THE DAY'S EVENTS; MANY ACFT WERE DEPARTING THE ARPT USING 2 RWYS; RWY 9 AND THE TXWY PARALLEL TO RWY 9. NO AIR TO GND COM WAS USED; ONE WAY ONLY FROM A TAPE WHICH DIRECTED TFC TO 'TAXI TO RWYS 9 AND 9L VIA 'THE PERIMETERS.' ALMOST ALL DEPARTING ACFT WERE ON THE S SIDE OF THE ARPT. WHEN I LEFT THE EXHIBIT AREA AND WALKED TO MY ASSIGNED PARKING AREA I OBSERVED MANY ACFT TAXIING IN LINE ON THE S SIDE OF THE ARPT; BUT NONE ON THE N SIDE. I WALKED ALONG THE S PERIMETER TXWY TO THE E END; N PAST THE END OF RWY 27 AND NW TO MY ACFT WHERE WITH A FEW OTHERS; IT HAD BEEN PARKED BY GND CREW DIRECTION NEAR THE NE END OF RWY 23. THERE WERE NO FAA OR VOLUNTEER GND PEOPLE IN EVIDENCE ANYWHERE IN THIS AREA. AFTER LISTENING TO THE RECORDED INSTRUCTIONS; I ASSUMED; INCORRECTLY; THAT I WOULD FIND THE 'PERIMETER TXWY' BY TAXIING SW ON RWY 23. THERE STILL WERE NO GND PERSONNEL TO BE SEEN. AFTER A SHORT TAXI I STOPPED TO RESTUDY THE SIT. THE SETTING SUN MADE VISION TO THE W ALONG THE GND VIRTUALLY NIL. AS I STOPPED A SMALL WHEELED VEHICLE DRIVEN BY A RED-VESTED MAN PULLED ALONG SIDE; AND THEN IN FRONT; MOTIONING TO ME TO TURN BACK. AS I TURNED A SMALL DEPARTING JET; JUST AIRBORNE PASSED ACROSS RWY 23. WHAT I HAD ASSUMED WAS 'THE PERIMETER TXWY' WAS THE PARALLEL! NOT MARKED AS A RWY AND NOT VERY PLAIN TO SEE ON THE SMALL SCALE OF THE ARPT DIAGRAM. I THEN REALIZED THAT DESIRED ROUTING WAS PAST THE BASE OF THE TWR. SUGGESTIONS: OBVIOUSLY I SHOULD HAVE STUDIED THE AVAILABLE ROUTES TO THE W END MORE CAREFULLY; ESPECIALLY SINCE NO OTHER ACFT WERE MOVING ON THE N SIDE AT THAT TIME WHILE DOZENS OF ACFT WERE MOVING ON THE S SIDE. GND CTL CREW SHOULD HAVE BEEN STATIONED AT ALL RWY/TXWY INTXNS IN THE ABSENCE OF RADIO CTL. THE INTXNS WITH THE TEMPORARY RWY SHOULD HAVE BEEN WELL MARKED WITH SIGNS. IT WOULD HAVE HELPED IF THE RECORDED VOICE HAD DIRECTED TFC ON THE N TO 'TAXI VIA THE TWR APRON' OR WORDS TO THAT EFFECT; A ONE PAGE HANDOUT TO ARRIVING PLTS SHOWING DEP TAXI ROUTING AND PROC WOULD BE VERY USEFUL. QUITE A NUMBER OF THINGS COULD BE CHANGED TO MAKE THIS KIND OF PROB LESS LIKELY IN THE FUTURE.