NMAC. TCASII. ARPT RWYS 34R AND 35 CTRLINES CONVERGE S OF ARPT. TFC LNDG ON RWY 35 USE DIFFERENT TWR FREQ THAN THOSE ON RWY 34R. TFC LNDG SIMULTANEOUSLY ON BOTH RWYS CONVERGE VERY CLOSE AND IN THIS INSTANCE; AN NMAC -- AND NEITHER ACFT HEARS THE OTHER ON THE RADIO.

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WE WERE ON DOWNWIND FOR RWY 34L AT SLC WHEN THE TWR OFFERED US RWY 34R. WE ACCEPTED AND WIDENED OUR BASE LEG. I NOTICED A TARGET ON TCASII AT ABOUT OUR ALT AND APPARENTLY LINED UP FOR RWY 34R. I ASKED THE OTHER CREW MEMBERS IF THEY COULD SEE HIM SINCE I WAS IN A 30 DEG L TURN AT THE TIME. MY CREW SAW HIM AND TOLD ME HE WOULD PROBABLY BE CONTINUING EBOUND OVER HWY 2100 FT. WE SUBSEQUENTLY GOT A TA FROM THE TCASII AND I STEEPENED MY BANK AND CLBED TO KEEP CLR. WE PASSED VERY CLOSE AND ABOVE THE TARGET; WHICH THE FO DESCRIBED AS A LOW WING. THE FO THEN QUERIED THE TWR; WHO RESPONDED WITH 'MY APOLOGY; THAT ACFT IS ON FINAL FOR RWY 35. HE IS ON THE OTHER TWR FREQ.' I HAVE ALWAYS FELT THAT SIMULTANEOUS OPS ON RWY 34R AND RWY 35 ARE EXTREMELY HAZARDOUS AND POSITIVELY SHOULD NOT BE CONDUCTED. THE EXTENDED CTRLINES INTERSECT WITHIN A SHORT DISTANCE; MAKING SIMULTANEOUS STRAIGHT-IN FINAL APCHS IMPOSSIBLE. THE 2 RWYS HAVE DIFFERENT TWR FREQS; MAKING IT IMPOSSIBLE FOR THE FLCS TO ESTABLISH SITUATIONAL AWARENESS. THIS INCIDENT REINFORCES THAT OPINION. ADDING TO THE WORKLOAD WAS THE FACT THAT I WAS TRYING TO SPACE MYSELF ON A B737 AHEAD OF US. HAD I BEEN ADVISED OF ANY TFC FOR RWY 35 I WOULD NOT HAVE ACCEPTED THE VISUAL FOR RWY 34R. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR CAPT CONFIRMED THE NMAC WAS EXTREMELY CLOSE; THOUGH BEING IN THE L SEAT AND STEEPENING HIS BANK; HIS FLC SAID 200/100 FT. HAD HE KNOWN THAT APCHS WERE IN PROGRESS ON RWY 35; HE WOULD HAVE REFUSED THAT RWY. THE FLC SAW THE TFC ON TCASII; BUT ASSUMED IT WAS VFR TFC FOLLOWING RTE 2100 WHICH IS A HEAVILY TRAVELED VFR CORRIDOR. RPTR CAPT HAS COMPLAINED FOR A LONG TIME ABOUT THE ACFT PROCS REGARDING THOSE RWY PROBS.