AN LGT STOPPED IN THE MIDDLE OF THE DISPLACED THRESHOLD OF THE LNDG RWY CAUSING AN LTT TO TAKE EVASIVE ACTION.

Narrative

GND CTL TOLD US (ACR LGT) TO EXPEDITE TAXI AND CROSS RWY 4L AT THE END; TFC ON FINAL. BECAUSE OF CONSTRUCTION; WE HAD TO TAXI AND CROSS RWY 4L AT THE VERY END OF THE DISPLACED THRESHOLD; WHERE THERE'S A LOT OF PAVED SURFACE THAT IS NOT MARKED WELL; NOR IS THERE GOOD SIGNAGE. I SAW THE ACR Z LTT TWIN ENG ON SHORT FINAL AS I TURNED THE CORNER. I DID NOT LIKE THE SEPARATION; SO I STOPPED; EXPECTING TO HOLD SHORT OF RWY 4L. IN FACT; I STOPPED IN THE MIDDLE OF THE DISPLACED THRESHOLD. EVEN THOUGH I REALIZED MY MISTAKE AND CONTINUED TAXIING; THE ENGS DID NOT SPOOL UP QUICKLY; AND TWR TOLD THE COMMUTER TO GAR. HE SAID HE COULD FLY OVER US AND CONTINUE SINCE WE WERE (BY THEN) MOVING AGAIN. I'M NOT SURE IF HE WENT AROUND. BOSTON IS NOT AN EASY PLACE TO TAXI OUT FOR RWY 9 BECAUSE ONE MUST CROSS RWY 4L/22R AT SIERRA. BY HAVING US GO BEYOND SIERRA AND CROSS AT THE END BECAUSE OF CONSTRUCTION; THE EXTENDED CTRLINE OF RWY 4L/22R; MEANING THE DISPLACED THRESHOLD AREA; IS VERY HARD TO DEFINE. I WAS NOT HAPPY WITH THE EXPEDITED TAXI CLRNC; YET I ENDED UP EXACERBATING EVENTS BY STOPPING SMACK IN THE MIDDLE. ALSO; I AM A CHK AIRMAN; AND THIS WAS THE VERY FIRST LEG OF A BOSTON FO'S IOE. NEXT TIME; I WILL NOT ACCEPT AN EXPEDITED CLRNC. I'LL JUST TAXI NORMALLY AND HOLD SHORT. WITH A STUDENT; I NEED A SLOWER PACE.