RWY TRANSGRESSION. CROSSED HOLD SHORT LINE.

Narrative

INSTRUCTED BY SFO GND (121.8) TO TAXI FROM GATE 10 AND TO FOLLOW A B-757 OUT TO RWY 1R. WE FOLLOWED THE B-757 OUT TXWY B TO THE APCH END OF RWY 1R. THE B-757 TAXIED INTO POS AND WAS HOLDING ON THE RWY WHILE WE WERE HOLD SHORT. (USED DIAGONAL TXWY) AFTER B-757 DEPARTED WE WERE CLRED INTO POS TO HOLD BY TWR AND WERE ASKED BY TWR IF WE HAD SEEN TXWY MARKING ON THE TAXI-RTE WE HAD FOLLOWED. WE DID NOT. WE HAD SIMPLY FOLLOWED THE B-757 OUT TO THE RWY AS INSTRUCTED BY GND CTL. IF ATC DOESN'T WANT THE DIAGONAL TXWY TO RWY 1R USED; IT SHOULD EITHER BE X'ED OUT OR GND CTL SHOULD ADVISE ACFT TO TAXI OUT USING FULL RWY LENGTH. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THOUGH RPTR SAYS HE DOESN'T KNOW WHY TWR QUESTIONED THEM ABOUT TXWY MARKINGS; AND THAT THEY HAD DONE EXACTLY AS THE ACFT IN FRONT OF THEM; APPARENTLY THEY MUST HAVE CROSSED THE HOLD SHORT LINE. THE HOLD SHORT MARKING ON TXWY B IS CLRLY VISIBLE AND XING IT COULD BE THE ONLY REASON FOR THE TWR TO REPRIMAND THE FLC. RPTR SAYS TWR CTLR SEEMED UPSET WITH THEM; SO THEY SUBMITTED RPTS.