PLT OF AN SMA SEL FAILED TO FOLLOW TAXI INSTRUCTIONS AFTER LNDG RESULTING IN TAXI ON THE WRONG DIRECTION TXWY.

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I STUDIED THE REEDR3 STAR THAT WOULD BRING ME TO THE APCH ROUTING; THE SL13.SLI SID FOR THE DEP; AND THE ARPT DIAGRAM FOR ANY POSSIBLE GND TAXIING. I READ THE STANDARD TAXI ROUTING AND NOTED THE ATC NON-VISIBLE AREA ALONG THE TXWY 48; 49 ROUTING; WHILE MENTALLY COMMENTING ON THE NUMERICAL DESIGNATIONS VERSES PHONETIC ALPHABET LABELING NORMALLY SEEN. THE LNDG WAS UNEVENTFUL BUT I WAS IMMEDIATELY REQUESTED TO 'TURN L NEXT TXWY WITHOUT DELAY.' THIS WAS TXWY 47. I WAS GIVEN A CLRNC TO TAXI ACROSS RWY 24L EITHER WITH THE VERBIAGE 'IMMEDIATELY OR WITHOUT DELAY' THE URGENCY TO COMPLY WAS MENTALLY SENSED. PLT INACTION -- UPON INITIAL GND CONTACT DID NOT REQUEST A 'PROGRESSIVE TAXI' NOR DID THE GND CTLR ASK WHERE WE WERE PARKING. AFTER CLRING RWY 24L GND CLRED US TO 'TURN R TANGO INNER (?) L ON TXWY 49 HOLD SHORT OF KILO INNER; CONTACT GND 121.75' (THIS IS MY BEST MEMORY USING THE CHART FOR VALIDITY). I REMEMBER READING BACK A TXWY NUMBER; EITHER 49 OR 48 AND THE WORD 'L.' HAD THE TAXI INSTRUCTIONS SAID FIRST L; OR SECOND L FOR TXWY 49? I DO REMEMBER '40' SOMETHING AND 'L.' THE GND CTL FREQ WAS VERY BUSY; AS WAS THE TAXIING TFC AROUND OUR ACFT. I ALSO WAS TRYING TO DETERMINE WHERE I WOULD HAVE TO CROSS THE OTHER 2 ACTIVE RWYS TO ARRIVE AT THE GENERAL AVIATION RAMP. MY MENTAL WORKLOAD WAS HIGHER NOW THAN ACTUALLY ON THE APCH; THE RADIO TFC; HEAT AND JET EXHAUST ADDED TO THE ENVIRONMENT. I TURNED L (1ST L?) ONTO WHAT I PERCEIVED TO BE TXWY 49 AND PROCEEDED TO TAXI TOWARD THE 50 YD LINE. AT THIS TIME I WAS STILL MONITORING THE CONGESTED N GND FREQ; BUT THEY COULD NOT SEE MY ACFT. I HAD THE CHART ON MY CLIPBOARD ORIENTED CORRECTLY FOR THE DIRECTION OF TRAVEL. I HAD EVEN HIGH-LIGHTED THE TXWY 49 ROUTING FOR QUICK REF. WHILE TAXING I NOTED THAT THERE WAS NOT A PARALLEL TXWY TO MY L; BUT I WAS BUSY LISTENING FOR MY N NUMBER ON THE RADIO AND TAXIING THE ACFT. SOMETHING WAS WRONG WITH THE 'PICTURE;' BUT THE PERCEPTIONS HAD NOT BEEN ASSIMILATED. AS WE APCHED TXWY L48 I NOTED AN ACFT OPPOSING OURS (757?) AT TXWY J OUTER (?) I COULD NOT JUDGE IF HE COULD TURN R OR L PRIOR TO OUR ACFT. I COULD NOT BREAK INTO THE RADIO TFC TO QUERY GND SO I STOPPED THE ACFT PRIOR TO L48 (STILL THINKING; MAYBE HE WILL TURN L ON L48?). I HAD SWITCHED TO GND COMPLEX S BUT COULDN'T GET A WORD IN. FINALLY WE WERE ASKED IF WE COULD TURN ONTO L49. IN SPITE OF HAVING L48 ON MY R; I STILL PERCEIVED; VIA THE CHART; FOR OUR ACFT TO BE ON TXWY 49 AND THAT WOULD HAVE REQUIRED A L TURN -- BUT THERE WAS NO TXWY TO MY L. SO I QUERIED; 'WHAT DIRECTION OF TURN?' NOW MY PERCEPTIONS OF OUR POS WERE TOTALLY AMISS. A COMMUTER FLT THAT HAD A VISUAL ON OUR ACFT BARKED ON THE RADIO THAT WE 'COULD' TURN R ONTO L48 TO REJOIN TXWY 49. WE TURNED R ONTO TXWY 49 AND CONTINUED WITH AN ESCORT BY THE OPS COORDINATOR. ONLY AFTER STOPPING WAS THE ERROR FULLY REALIZED. THERE WAS NEVER A 'SAFETY' ISSUE BUT THE DELAYS FOR THE JETLINERS WAS SURELY NOT APPRECIATED. NOT UNTIL RETURNING HOME THAT NIGHT DID I SEE HOW WE COULD HAVE MADE THE WRONG TURN ONTO THE NBOUND TXWY.