MLG FLC TAXIES PAST HOLD LINE OF ACTIVE RWY.

Narrative

AT DETROIT CITY ARPT; WE PUSHED BACK FROM GATE. WE WERE CLRED TO TAXI SHORTLY THEREAFTER. OUR CLRNC; AS NEAR AS I REMEMBER; WAS 'TAXI UP TO RWY 25 BUT DO NOT TAXI ONTO THE RWY.' AT THE TIME; THIS MADE SENSE TO ME BECAUSE AN SMA X WAS HOLDING FOR TKOF JUST SHORT OF THE RWY EDGE ON THE N SIDE OF THE RWY. THERE WAS ALSO AN SMA Y HOLDING SHORT OF MY TAXI RTE ON ANOTHER XING TXWY. AS I STARTED TAXIING S ON TXWY A; THE SMA Y; WHO WAS FACING E ON TXWY I; WAS TOLD TO HOLD SHORT OF A TO 'LET ACR (US) GET BY.' AS I BEGAN TO TAXI; ANOTHER ACFT LANDED ON RWY 25 AS THE SMA X WAS HOLDING SHORT OF RWY 25 JUST NW OF THE WHITE LINES MARKING THE EDGE OF RWY 25 DISPLACED THRESHOLD. NEEDLESS TO SAY; IT WAS VERY CROWDED AND CONFUSING. AS I SLOWLY TAXIED TOWARD RWY 25; THE SMA X WAS CLRED FOR TKOF; AT WHICH TIME I MOVED MY ACFT TOWARD THE SPOT HE HAD VACATED. AT THE TIME I THOUGHT GND CTL WANTED ME TO GET UP NEXT TO RWY 25 WHERE THE SMA X HAD BEEN AND WAIT UNTIL THE SMA Y HAD TAKEN OFF. IN DOING THIS; I TAXIED PAST A 'DASHED' HOLD SHORT LINE THAT WAS ALMOST EVEN WITH TXWY I; WHERE THE SMA Y WAS STOPPED; SOME DISTANCE FROM THE EDGE OF RWY 25. AFTER I WAS CLRED ONTO RWY 25 TO TAXI TO RWY 33; I REALIZED I HAD POSSIBLY VIOLATED THE 'RWY ENVIRONMENT'. I TRIED TO ASK GND AND TWR IF THEY HAD MEANT FOR ME TO TAXI UP CLOSE TO RWY 25; BUT THE FREQ WAS SO BUSY THAT I WAS UNABLE TO GET AN ANSWER. ALSO; THE COCKPIT WAS BUSY WITH THE 'TAXI CHKLIST.' AS WE APCHED RWY 33; WE WERE CLRED FOR AN IMMEDIATE TKOF; SO I CONCENTRATED ON COCKPIT DUTIES; FINISHED THE CHKLIST; AND MADE A QUICK TKOF. I NEVER WAS ABLE TO TALK TO GND OR TWR ABOUT WHAT HAD HAPPENED. THE BOTTOM LINE IS THIS: I TRIED TO COMPLY WITH INSTRUCTIONS ISSUED BY GND CTL; AND THERE MAY HAVE BEEN A MISUNDERSTANDING DUE TO HVY TFC ON THE ARPT. CONTRIBUTING TO THE CONFUSION WAS THE VERY TIGHT SPACE ON THE TXWYS AT THE NE END OF RWY 25.