ACR CROSSES RWY WITHOUT CLRNC.

Narrative

FLT WAS CLRED TO TAXI TO RWY 9L IN MIA. CREW THOUGHT CLRNC WAS TO RWY 9R. CROSSED 12/30 (RWY) ENRTE TO 9R. WE THOUGHT WE WERE CLRED TO CROSS A RWY ENRTE. THIS IS AN EXAMPLE OF A PROBLEM RESULTING FROM THE RULE THAT CLRS ON TO CROSS ALL RWYS ENRTE TO AN ASSIGNED RWY. HAD WE REQUESTED CLRNC TO CROSS 12; THE GND CTLR MAY HAVE CAUGHT THE ERROR AND CORRECTED US. THERE WAS NO TFC USING 12 AT THE TIME AND NO CONFLICT RESULTED. ALSO IF I HAD THE FO ASK THE CTLR PERMISSION TO CROSS 12 IT WOULD HAVE BEEN CAUGHT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO. RPTR STATES THERE WAS NO EXCUSE FOR PROBLEM BUT HIMSELF. HE HAD A MIND SET ABOUT RWY IN USE AS MIA USUALLY HAS DEPS ON 9R AND LNDGS ON 9L. CTLR GAVE NO TAXIWAY GUIDANCE SO HE TOOK MOST DIRECT RTE TO WHERE HE THOUGHT THEY WERE CLRED. HAD A GUT FEELING JUST BEFORE XING RWY THAT THEY SHOULD CONFIRM CLRED TO CROSS. AFTER FACT; CTLR ASKED IF HAVING TROUBLE; THEN GAVE GUIDANCE TO GET BACK TO 9L; THEN ASKED IF THEY WOULD LIKE 9R. RPTR HAS STRONG FEELINGS ABOUT STANDARDIZING RWY NUMBERING SYSTEMS. FEELS LGW AND DEN HAVE EXCELLENT AND EASY TO FOLLOW SYSTEMS. LGW HAS CONSECUTIVE NUMBERING AND RED LIGHTS IN TAXIWAY AT RWY XINGS. THEY ARE DIRECTLY IN FRONT OF PLTS. DEN HAS COLORED LINES TO FOLLOW. ALSO FEELS IT WOULD BE EXTREMELY HELPFUL TO PAINT TAXIWAY IDENT ON THE TAXIWAY ITSELF. THAT IS WHERE PLT ATTN IS FOCUSED WHILE TAXIING; NOT ON SIDE AREAS.