AN AIRBUS A319 FLC RECEIVED A TCASII RA DURING A ZID REQUESTED EXPEDITED DSCNT NEAR ROD.

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THIS CORRIDOR IS VERY BUSY. ZID DOES A GREAT JOB. IT GOES S IN A HURRY WHEN PLT/CTLR COM GETS JUMBLED. CMH ATIS IS A DANGER AS WELL (SHARES) SAME FREQ WITH OTHER ATC FACILITY. WE WERE IN THE DSCNT INTO CMH. ZID GAVE US AN INTERMEDIATE LEVELOFF AT FL240 WITH 'EXPECT LOWER ALT SHORTLY WHEN CLR OF TFC.' WE WERE THEN; AFTER PREVIOUS PHRASE; GIVEN DSCNT CLRNC TO FL210 'AND TO EXPEDITE.' THE FO (WHO WAS ACTING AS THE PF) SELECTED 'EXP' THE EXPEDITE BUTTON ON THE FCU AND BEGAN OUR DSCNT. AT APPROX FL234 WE WERE ALERTED BY THE TCASII OF A 'TA.' AT ABOUT THE SAME TIME ATC ASKED US OUR ALT AND AT THE SAME TIME OUR TCASII SYS UPGRADED THE TA TO AN RA AND TO 'CLB; CLB.' AT ABOUT THE SAME TIME I SAW THE MD80 ACFT OUT OF THE FO'S FORWARD WINDOW AND SIMULTANEOUSLY PULLED BACK ON THE STICK TO COMPLY WITH THE TCASII RA. I ALSO REPLIED TO ATC'S INQUIRY OF OUR ALT AS THAT WE WERE COMPLYING WITH A TCASII RA. THEY (ATC) THANKED US AND CLRED US TO FL190. FLC FOLLOWED ALL PROCS AND INSTRUCTIONS. TCASII MAY HAVE CAUSED LOSS OF SEPARATION. RADIO CONGESTION MAY HAVE CONTRIBUTED TO LOSS OF SEPARATION. CMH ARPT ATIS MAY CAUSE CREWS TO DIVERT THEIR FULL ATTN DEEP INTO DSCNT WHEN TFC CONFLICTS ARE AT THEIR GREATEST!