ACR B757 FLC BECOMES CONFUSED WHEN ISSUED RETURN TO GATE TAXI INSTRUCTIONS AND TURNS ONTO ANOTHER ACTIVE RWY. TWR GND CTLR RECLRS ACFT VIA ANOTHER RETURN RTE SO AS NOT TO IMPACT TFC TURNING FINAL. FLC BELIEVES TXWY AND RWY SIGNAGE IN THE AREA OF INTERSECTING RWYS IS NOT CLR; CAUSING CONFUSION. CAPT; ON CERTIFICATION CHK RIDE; FIRST TIME ON ARPT.

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WE WERE HOLDING SHORT OF RWY 9 ON TXWY B AT THE TXWY B HOLD POINT. WE EXPERIENCED A MECHANICAL PROB WITH THE ACFT REQUIRING A RETURN TO GATE. WE WERE CLRED TO TAXI INTO RWY 9. AS WE TAXIED TO RWY 9; WE CROSSED WHAT APPEARED TO BE A CLOSED ASPHALT AREA. IT LATER PROVED TO BE THE OVERRUN FOR RWY 9/27. WE TAXIED TOWARD RWY 4L; BELIEVING IT TO BE RWY 9. TWR INSTRUCTED US TO QUICKLY TAXI ACROSS RWY 4L DUE TO AN ACFT TURNING BASE FOR RWY 4L. WE WERE THEN CLRED ONTO TXWY V AND HOLD SHORT OF RWY 9. WE RETURNED TO THE GATE; CONTACTED TWR AND WERE TOLD THAT NO LOSS OF SEPARATION OR TFC CONFLICT HAD OCCURRED. CONTRIBUTING FACTORS: 1) I WAS NOT FAMILIAR WITH BOSTON ARPT. 2) THERE WERE NO CLR SIGNS OR MARKINGS TO IDENT RWY 9 AT INTXN B. 3) BOS 10-9 CHART DOES NOT CLRLY IDENT THIS LOCATION OF ARPT. SUGGESTIONS: 1) INSTALL CLR MARKINGS AND SIGNAGE FOR THIS LOCATION OF ARPT. 2) IMPROVE THE BOS 10-9 CHART. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATES HE COULD NOT CLRLY IDENT THE ASSOCIATION BTWN TXWY B AND THE RWY 9/27 STOPWAY. ON TXWY B; IT WAS CLRER WHEN APCHING THE RWY 4L/22R STOPWAY. WHEN TOLD TFC WAS ON BASE LEG FOR RWY 4L; SIGNAGE WAS CLR AHEAD FOR TAXIING ACROSS THE RWY 4L/22R STOPWAY ONTO TXWY V. THE RPTR'S THOUGHT FOR IMPROVEMENT IS BASED ON THE FACT THE 'MOST TFC' TO BOS IS ITINERANT; AND THE ARPT SHOULD ERR ON EXTRA SIGNAGE. MAYBE PAINTING '9' ON THAT PORTION EFFECTING THE RWY 9 STOPWAY AND '4L' FOR THE RWY 4L STOPWAY WOULD BE CLRER FOR THOSE USING THAT AREA. FOR INCLEMENT TIMES; ADDITIONAL SIGNS TO MARK THE AREA. CALLBACK CONVERSATION WITH FACILITY SPECIALIST REVEALED THE FOLLOWING INFO: DESCRIBED THE AREA IN QUESTION AS CLRLY MARKED. HE ADVISED THERE HAD BEEN 'VERY FEW INCIDENTS' THIS YR IN THAT AREA. THE STOPWAY AREAS ARE CHEVRONED AND PAVED. HE WAS AWARE OF ONLY 1 INCIDENT INVOLVING AN ACR; OCCURRING WITHIN THE LAST COUPLE MONTHS. THE OTHER INVOLVED GA TFC.