C208 PLT TAXIED WITH ASSUMED CLRNC CONFIRMATION AND HAD A RWY INCURSION AT PIT.

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PITTSBURGH WAS USING RWY 10L FOR ARRS AND RWY 14 FOR DEP; I WAS THE LAST OF FIVE CARGO FLTS FOLLOWING A LARGE ACR CARGO AIR BUS FROM THE RAMP N OF RWY 28R. I CALLED AND RECEIVED AN IFR CLRNC AND SWITCHED TO GND CTL AND WAITED BEHIND THE OTHER ACFT FOR A BREAK IN THE CHATTER. I CALLED GND; AND GOT A REPLY 'WHO IS THE LAST ACFT IN LINE?' I ANSWER BACK 'ACFT X.' GND CAME BACK WITH 'ACFT X... (TRANSMISSION BROKE UP)... CROSS RWY 28R TO RWY 14.' I READ BACK 'GOING TO RWY 14 ACFT X.' I BELIEVE MY READ BACK MAY HAVE BEEN BLOCKED BY ANOTHER CALL. AFTER CROSSING THE RWY AND PROCEEDING DOWN TXWY NOVEMBER; GND CTL CALLED AND ASKED 'ACFT X; DID I TALK TO YOU?' I REPLIED 'YES; YOU CLRED ME TO CROSS RWY 28 TO RWY 14.' HE REPLIED 'I DON'T THINK I CLRED YOU' OR; 'I DIDN'T OR SOMETHING LIKE THAT. WHEN I REACHED MY DEST; FSS TOLD ME TO CALL THE PITTSBURGH TWR. I THINK SOME OF THE CONTRIBUTING FACTORS ARE: 1)GND CTL TRYING TO HURRY SIX ACFT ACROSS AN ACTIVE RWY. 2)POOR COM DUE TO AMOUNT OF CALLS AND PLTS AND CTLRS BLOCKING ONE ANOTHER. 3)NONSTANDARD RADIO CALLS.