B767 FLT CREW RPTS CONFUSION WITH TAXI CLRNC AT SFO INVOLVING TWO TXWYS LABELED 'S' LOCATED ON OPPOSITE SIDES OF RWY 10L.

Narrative

WE PUSHED BACK FROM THE GATE AT SFO AND STARTED ENGS. WE CALLED GND AND RECEIVED A TAXI CLRNC 'TAXI TO RWY 10L VIA TXWYS A; E; B; Z; AND S.' WE REVIEWED OUR DIAGRAMS AND STARTED OUR TAXI. WE WERE ON TXWY A SO WE FOLLOWED IT NORTHBOUND UNTIL WE INTERCEPTED TXWY E; MADE THE DOGLEG ON TXWY E TO INTERCEPT TXWY B; FOLLOWED TXWY B WESTBOUND AND CONTINUED WESTBOUND WHEN IT TURNED INTO TXWY Z. MY UNDERSTANDING OF THE CLRNC WAS THAT WE WERE CLRED TO TAXI ON TXWY Z UNTIL REACHING TXWY S; THEN TO FOLLOW TXWY S TO THE THRESHOLD OF RWY 10L; AND HOLD SHORT. LOOKING AT THE CHART; THE ONLY PLACE I SAW TXWY S WAS TO THE NORTHEAST OF RWY 10L; SO I PLANNED TO FOLLOW TXWY Z AROUND THE END OF BOTH RWYS 10R AND 10L; THEN INTERCEPT TXWY S. OOPS; IT TURNS OUT THERE IS A SMALL SEGMENT OF TXWY S THAT RUNS FROM TXWY Z TO THE THRESHOLD OF RWY 10R; AND CONTINUES TO THE THRESHOLD OF RWY 10L. WE PASSED THE FIRST INTXN OF TXWY S; THE GND CTLR SPOTTED US; AND HE HAD US TURN ON TO TXWY S2 TO INTERCEPT TXWY S; AND HOLD SHORT OF RWY 10L. I THINK THAT TXWY S SHOULD BE RELABELED ON EITHER THE LEFT SIDE OF RWY 10L; OR THE RIGHT SIDE OF RWY 10L (WHICH LEADS TO RWY 10R); OR THERE IS A POTENTIAL THAT ANOTHER ACFT COULD DO THE SAME THING; AND POSSIBLY HAVE A CONFLICT. IT DOESN'T; TO ME; MAKE SENSE TO HAVE THE TXWYS MARKED IN SUCH A WAY THAT A CLRNC CAN BE INTERPRETED IN TWO DIFFERENT WAYS; SO THAT THE PLT AND CTLR ARE NOT CLR ON WHAT IS EXPECTED; OR WHAT WILL HAPPEN.CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR INDICATED THAT THE FLT CREW HAD NOT OPERATED FROM THAT AREA OR RWY PREVIOUSLY. DUE TO THE WIND AND WX CONDITIONS THE ARPT WAS ON SOUTH OPERATIONS AND THE RPTR NEVER ENCOUNTERED THIS RWY DIRECTION. WX WAS RAINY AND THE TXWYS WERE WET; CAUSING SOME CONFUSION WITH THE LINES AND DIRECTIONS. THE RPTR INDICATED THAT HIS AND HIS FO'S LACK OF FAMILIARITY WITH THE ARPT OPERATIONS FROM THAT RWY WAS THE PRIMARY CAUSE OF THE CONFUSION. HOWEVER; HIS CONCERN WAS THAT THE MULTIPLE WAYS TO ARRIVE AT THE RWY VIA THE TXWY S IS CONFUSING AND HE SAID THAT CHANGING THE TXWY DESIGNATION MAY HELP WITH THE CONFUSION.