AN E145 CREW; TAXIING FOR TKOF AT ORD; UNABLE TO LOCATE 'BRAVO BRIDGE;' QUERIED GND CTL AS TO ITS LOCATION.

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AFTER PUSHBACK FROM THE CONCOURSE AT ORD; RAMP CTL INSTRUCTED OUR FLT TO SEQUENCE WITH TFC MOVING SSW ON THE TXWY B LINE AND MONITOR GND CTL. THIS WAS ONLY MY SECOND TRIP INTO ORD; BUT THE CAPT HAD MULTIPLE PREVIOUS VISITS IN THE PAST 2 YRS. AFTER APPROX 10 MINS; GND CTL INSTRUCTED OUR FLT TO 'TAXI TXWY A9 TO TXWY B; HOLD SHORT OF THE BRAVO BRIDGE.' I READ BACK THE CLRNC AND REPEATED THE INSTRUCTIONS TO THE CAPT; WHO HAD BEEN TALKING TO THE COMPANY ON COM #2 AND WAS NOT MONITORING COM #1. WE BEGAN TAXIING AND THE CAPT INDICATED THAT HE DID NOT KNOW WHERE THE BRAVO BRIDGE WAS LOCATED. SO I CONTACTED GND CTL FOR CLARIFICATION; ASKING 'WHERE IS THE BRAVO BRIDGE?' GND CTL WAS VERY BUSY AND NOW SEEMED IRRITATED WITH US. GND REPEATED HIS INITIAL TAXI INSTRUCTIONS; ADDING THAT 'THE BRAVO BRIDGE IS ON TXWY B; THAT'S WHY IT'S CALLED 'BRAVO BRIDGE'.' THE CAPT AND I STILL HAD NOT BEEN TOLD WHERE ON TXWY B THE 'BRAVO BRIDE' WAS; AND THE SEMI-CIRCULAR SHAPE OF THE TXWY TURNS THROUGH OVER 180 DEGS; FURTHER COMPLICATING THE TASK. WE TAXIED SLOWLY; AND IN DOING SO; LOCATED A NOTE ON THE ARPT DIAGRAM '2) CAUTION: NO ACFT ARE PERMITTED TO STOP ON BRIDGED TXWYS A AND B.' THE CAPT AND I DECIDED THAT THIS PROBABLY INDICATED THE 'BRAVO BRIDGE' AND STOPPED THERE; AND SWITCHED TO MONITOR TWR AS INSTRUCTED BY GND CTL'S LAST XMISSION. THE REMAINDER OF THE FLT WAS UNEVENTFUL. CONTRIBUTING FACTORS WERE NIGHTTIME; IMC; 1/4 MI VISIBILITY WITH RAIN AND FOG; A VERY BUSY TERMINAL AND EXTREMELY CONGESTED GND CTL FREQ. NEITHER CREW MEMBERS ARE BASED AT ORD; AND ARE UNFAMILIAR WITH LCL 'NORMS' AND TERMINOLOGY. WHILE LCL TERMS LIKE 'PENALTY BOX' AND 'SCENIC HOLDING PAD' ARE LABELED ON THE ARPT DIAGRAM; 'BRAVO BRIDGE' IS NOT; BUT MUST BE INFERRED FROM A NOTATION ON THE DIAGRAM. IT WAS DIFFICULT TO COMMUNICATE WITH GND DUE TO CONGESTION ON THE FREQ. MUCH; IF NOT ALL; OF OUR CONFUSION COULD HAVE BEEN AVOIDED IF GND HAD INSTRUCTED US TO TAXI TO RWY 32R VIA TXWY A9 AND TXWY B; HOLD SHORT OF THE RWY 32R ILS CRITICAL AREA. IT IS INTERESTING TO NOTE THAT THE 'BRAVO BRIDGE' IS NOTED ON THE CHART AS 'RWY INCURSION HOT SPOT #7.' PERHAPS OTHER PLTS HAVE NOT REALIZED WHERE THE 'BRAVO BRIDGE' IS EITHER.