CPR X RWY INCURSION.

Narrative

DURING TAXI TO RWY 21L AT DTW I INADVERTENTLY CROSSED THE RWY AND STOPPED ON THE OTHER SIDE INSTEAD OF HOLDING SHORT PRIOR TO THE RWY INTXN AS INSTRUCTED. FROM TXWY S5 AT DTW; THE ONLY WAY TO TAXI TO FULL LENGTH RWY 21L IS TO CROSS THE RWY AND TAXI DOWN RWY 9/27 TO THE END. MY INITIAL REACTION WAS TO DO JUST THAT AND KEPT A LOOKOUT FOR THE SIGNS FOR RWY 9/27. BEFORE I KNEW IT I HAD CROSSED RWY 21L (ONE OF THE 3 ACTIVE PARALLEL RWYS) WITHOUT EVEN NOTICING. IT WAS DARK AND WELL INTO THE NIGHT AND FATIGUE WAS SETTING IN. I AM UNSURE AS TO THE PLACEMENT OF RWY MARKINGS FOR RWY 21L AND I MIGHT HAVE MISSED IT DUE TO THE WIDTH OF TXWY S. I WAS ASKED TO CONTINUE R ON RWY 9/27 TO HOLD SHORT OF RWY 21L AFTER THE CTLRS DISCOVERED THE INCURSION. THERE WAS NO COMPROMISE TO SAFETY. THE SAME NIGHT ARRIVING AT SYRACUSE HANCOCK INTL; I LANDED WITHOUT EVER BEING TURNED OVER TO THE TWR FROM APCH CTL; CLRED FOR THE VISUAL TO RWY 28. THEY SAID IT WASN'T A PROB. FLYING WAS WITHOUT INCIDENT! CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED HE WAS FLYING SINGLE PLT. ALSO STATED HE WAS VERY TIRED BECAUSE OF BEING AT THE ARPT ALL DAY. HE SAID HE HAD ARPT TAXI CHART OUT BUT WAS HARD TO READ BECAUSE OF NIGHT CONDITIONS. DTW FACILITY SUPVR STATED THERE ARE HOLD LINES AND SIGNS AT RWY INTXN TXWY S5.