LGT TAXIES PAST ASSIGNED TXWY ALMOST ENTERS RWY.

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WHILE TAXIING FROM GATE AT TERMINAL 2 AT PHX ARPT AND PREPARING FOR THE TAXI CHKLIST; WE WERE CLRED VIA TXWY E TO TXWY S FOR A RWY 26R DEP. THIS RAMP/TAXI AREA IS JUST S OF TERMINAL 2 AND CONCOURSE S. IT USED TO BE ONE TAXI/RAMP AREA; HOWEVER DUE TO INCREASED TFC AND CONGESTION IN THIS AREA IT HAD BEEN DIVIDED INTO 2; UNDIVIDED TXWYS (D AND E). THIS WAS TO ALLOW SIMULTANEOUS; 2-WAY TFC IN THIS AREA. WHILE PREPARING FOR THE TAXI CHKLIST; AND THINKING THAT I NEEDED TO CROSS ONE TXWY PRIOR TO REACHING TXWY E; I INADVERTENTLY MISTOOK TXWY E4 AS THE CONNECTING TXWY LEADING TO TXWY E. NOT REALIZING THAT I HAD IN FACT ALREADY PASSED THE UNMARKED TXWY D WHICH IS PART OF THAT RAMP AREA. I DO NOT RECALL THE 'HOLD SHORT' LINE FOR RWY 26L ON TXWY E4; HOWEVER I NOTICED THE WIDE WHITE RWY SIDE OR BOUNDARY LINE FURTHER AHEAD AND I IMMEDIATELY STOPPED. THE FO WAS ALSO PREOCCUPIED WITH PRE TAXI/TAXI DUTIES. THE FLT ATTENDANTS NOTICED THE ABRUPT STOP BUT NO PROB WAS CREATED IN THE CABIN AREA EITHER. I INDICATED/NOTIFIED GND CTL THAT I HAD MISSED THE TURN TO TXWY E AND WAS HOLDING SHORT OF RWY 26L. WE WERE THEN CLRED TO BACK TAXI ON RWY 26L AND TO REJOIN TXWY E AT TXWY E5 AND CONTINUE TAXI AS PREVIOUSLY CLRED TO RWY 26R. THERE WAS NO INDICATION BY US OR GND CTL THAT THERE HAD BEEN ANY ENCROACHMENT OR ANY TFC OR SAFETY PROB CREATED. THE WIDE; WHITE RWY SIDE LINES WAS WHAT REALLY STUCK OUT WHILE I WAS ALLOWING MYSELF TO BE DISTRACTED BY TAXI OUT PREPARATIONS AS WELL AS MY CONFUSION AS TO THE LOCATION OF TXWYS D AND E IN THAT AREA. I SHOULD HAVE ACCOMPLISHED MORE AFTER START AND TAXI PROCS PRIOR TO TAXI (IE; AIRSPD BUGS; CTR OF GRAVITY NUMBERS/WTS; AND FLAP SETTINGS) AND PAY CLOSER ATTN TO AREAS THAT ARE NOT AS CLRLY DEFINED AS THEY ARE AT MOST ARPTS.