SMT CROSSED ACTIVE RWY WHILE MLG WAS TAKING OFF; LESS THAN STANDARD SEPARATION.

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AFTER LISTENING TO ATIS; I OBTAINED CLRNC ON 127.6 AS SMT X TO DEPART THE DEN TCA VFR NBND; MAINTAIN 7000'; DEP FREQ 126.9; SQUAWK XXXX. AFTER READING BACK THE CLRNC; I ADVISED CLRNC DELIVERY THAT I WAS READY TO TAXI FROM FBO RAMP WITH THE ATIS. I WAS ADVISED TO MONITOR GND ON 121.9 FOR TAXI CLRNC. (I REMEMBER THINKING THAT THIS WAS SOMEWHAT UNUSUAL; SINCE THE E-W TWR FREQ IS NORMALLY USED FOR ALL ACFT TAXIING OUT OF THE S SIDE OF THE ARPT; ESPECIALLY WHEN THE E-W RWYS ARE ACTIVE; AS THEY WERE TODAY.) (SOME CONFUSION IS INDICATED HERE. THE CTLR APPARENTLY THOUGHT I WAS AT THE N CARGO RAMP.) I ADVISED GND CTL THAT I WAS REQUESTING TAXI FROM FBO RAMP EXPECTING TO BE SWITCHED TO TWR ON 118.3 FOR TAXI. INSTEAD; GND CTL ADVISED ME TO EXPECT A RWY 7 DEP; AND INSTRUCTED ME TO HOLD SHORT OF RWY 8R AT BRAVO 4. A SHORT TIME LATER; I WAS ISSUED A CLRNC WHICH I HEARD AS FOLLOWS: 'SMT X HOLD SHORT OF 8L NOW AND MONITOR TWR ON 118.3.' SINCE THE FREQ WAS BUSY; I REPLIED WITH ONLY; 'SMT X ROGER;' AND; SEEING A MLG Y APPARENTLY HOLDING IN POS AT THE DEP END OF RWY 8R; PROCEEDED ACROSS THE RWY W/O DELAY; TUNING IN THE TWR FREQ 118.3 AT THE SAME TIME. AS I WAS XING RWY 8R I NOTICED THAT THE MLG Y WAS BEGINNING HIS TKOF ROLL AND REALIZED INSTANTLY THAT A PROB EXISTED. HOWEVER; IT WAS TOO LATE TO STOP AT THAT POINT; SO; ALREADY COMMITTED; I CONTINUED TO CROSS THE RWY VERY QUICKLY; THEN STOPPED AS SOON AS I WAS CLR; WAITING FOR THE INEVITABLE CALL FROM TWR. THE PLT IN THE RIGHT SEAT OF MY ACFT; ALTHOUGH HE SAID THAT HE WAS NOT REALLY PAYING CLOSE ATTN TO THE RADIO XMISSIONS; INDICATED THAT HE DID NOT SENSE ANY PROB AT THE TIME. IN RETROSPECT; SINCE I COULD HAVE AVOIDED THE INCURSION BY QUESTIONING THE CLRNC I THOUGHT I HAD BEEN ISSUED; I LARGELY ASSUME RESPONSIBILITY FOR THE INCIDENT. HOWEVER; I FEEL THAT THE INCIDENT WOULD NEVER HAVE OCCURRED HAD ANY ONE OF THE RECOMMENDATIONS BELOW BEEN FOLLOWED. RECOMMENDATIONS: 1) PLTS SHOULD READ BACK ALL CLRNCS AND QUESTIONS THOSE WHICH MAY IN ANYWAY BE CONFUSING. SUCH ACTION WOULD ALSO CATCH THE OCCASIONAL ERROR THAT A CTLR COULD MAKE IN ISSUING A CLRNC. 2) TAXIING ACFT SHOULD; WHENEVER POSSIBLE; BE ASSIGNED THE ACTIVE RWY TWR FREQ BEFORE APCHING THE RWY. IN THAT WAY; ALL PLTS OF POTENTIALLY CONFLICTING ACFT WOULD BE IN COM WITH THE SAME CTLR; AS WELL AS ABLE TO MONITOR ONE ANOTHER'S XMISSIONS. 3) IF POTENTIALLY CONFLICTING ACFT MUST; FOR SOME REASON; BE ASSIGNED DIFFERENT FREQS; THEN CTLRS SHOULD REFRAIN FROM RESTATING A CLRNC THAT HAS ALREADY BEEN ISSUED AND COMPLIED WITH. TO REISSUE SUCH A CLRNC ONLY RAISES THE POSSIBILITY THAT THE PLT WILL MISINTERPRET IT AS A NEW CLRNC. 4) IF A CTLR WISHES TO REINFORCE A CLRNC THAT HAS PREVIOUSLY BEEN ISSUED AND COMPLIED WITH; HE SHOULD PRECEDE THE REPEAT OF THE CLRNC WITH WORDS 'CONTINUE TO.' MANY CTLRS NOW USE THIS PHRASEOLOGY AND IT WORKS WELL. IN THE ABOVE INCIDENT; THERE WOULD HAVE BEEN NO DOUBT OF THE GND CTLR'S INTENT HAD HIS LAST XMISSION TO ME BEEN; 'SMT X CONTINUE TO HOLD SHORT OF 8R; MONITOR TWR NOW ON 118.3.' SUPPLEMENTAL INFO FROM ACN 82085: DURING TKOF NOTICED TWIN ENG AIRPLANE XING 8R FROM RIGHT TO LEFT DOWNFIELD. TWR SAID; '(TWIN) YOU WERE NOT CLRED TO CROSS. MLG Y CANCEL TKOF CLRNC.' AT THIS TIME MY AIRSPD WAS 100+ KTS AND THE TWIN WAS CLR OF THE RWY. I REPLIED; 'WE SEE HIM AND WE'RE CLR.' I CHOSE NOT TO ABORT AND CONTINUED TKOF. ON RETURN TO DEN ABOUT 3 HRS LATER; I CALLED DEN TWR. THE SUPVR SAID THEY HAD REVIEWED THE TAPES AND THE TWIN WAS TOLD TO HOLD SHORT OF RWY 8R. THE SUPVR ALSO SAID HE THOUGHT I SHOULD HAVE ABORTED SINCE THE TWR HAD TOLD ME TO DO SO. I REPLIED; THE TWR'S EXACT WORDS WERE; 'CANCEL TKOF CLRNC.' THE DECISION TO ABORT IS MINE AND SINCE MY AIRSPD WAS ABOVE 100 KTS; AND THE TWIN WAS CLR OF THE RWY; I DECIDED THE SAFEST COURSE OF ACTION WAS CONTINUING THE TKOF.