SMT'S UNAUTHORIZED TAXI CREATES A RWY INCURSION.

Narrative

I MISINTERPRETED TAXI INSTRUCTIONS ON THE ATIS. PROCEEDED FROM FUEL SVC TO RWY WITHOUT TAXI CLRNC. I WAS MONITORING TWR FREQ AND WAS PROCEEDING TO RWY 36; WHICH WAS ACTIVE RWY. I BEGAN TO TAXI ONTO RWY 29 (APCH END STEMS OFF OF 36) READY TO ADVISE TWR; 'READY FOR DEP 36.' APPARENTLY THE ACFT; WHICH LOOKED TO BE HOLDING FOR 36; DECIDED TO DEPART 29. I SAW HIM START TO DO A 180 DEG TURN. I KNEW I HAD A PROBLEM. AT NO TIME WERE PERSONS OR PROPERTY IN DANGER OF INJURY OR DAMAGE. TWR INSTRUCTED ME TO PROCEED ACROSS AND CLR 29 FOR DEPARTING ACFT. I HAVE NEVER HAD ANY PROBLEMS WITH ATC BEFORE AND FEEL I AM FAIRLY WELL VERSED IN GND AND AIR PROCS. THE PROBLEM WAS CAUSED BY POOR COCKPIT AND PRIORITY MGMNT. I HAD 5 AERIAL RECON MISSIONS TO FLY AND WAS ORGANIZING FLT MAPS WHILE LISTENING TO ATIS. FOR THIS SITUATION NEVER TO HAPPEN AGAIN I MUST PRIORITIZE MUCH MORE EFFICIENTLY. IN OTHER WORDS; WHEN IT'S TIME TO FLY; IN THIS CASE TAXI; CONCENTRATE ON THE TASK AT HAND. TAKE CARE OF THE PLANE AND FOLLOW PROCS. IF I WANT TO ORGANIZE SOMETHING DO IT PRIOR; NOT DURING THE RECEIVING OF IMPORTANT INFO.