LGT TAXIED ONTO ACTIVE RWY WHILE TAXIING FOR TKOF. RWY INCURSION.

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AFTER PUSHBACK FLT WAS GIVEN TAXI INSTRUCTIONS TO RWY 33 TO CROSS RWY 28. OUTBOUND; GND SAID THAT RWY 28 WAS AVAILABLE FOR TKOF AND WE ELECTED IT WITH INSTRUCTIONS TO CROSS RWY 22 ENRTE VIA OUTER. AT THE 'S' TURN TURNING TO PARALLEL RWY 28; I PICKED UP RWY 22 IDENT SIGN WITH THE TURN BUT FOLLOWED THE YELLOW TAXI LINE THAT CROSSED RWY 28 TOWARD RWY 33 TKOF END. SAW ACR B TAKING POS ON RWY 33 AND FOLLOWED; ENTERING RWY 28. GND ADVISED THAT WE WERE HEADING TO RWY 33 AS WE CROSSED RWY 28 BY MISTAKE AND ASK IF WE COULD USE RWY 33. WE CONFIRMED. WE WERE IN THE PROCESS OF DOING CHKLIST AND CONFIRMING WTS. BOTH CAPT AND FO CHKED BOTH WAYS AND 'RPTED' NO TFC TO EACH OTHER BEFORE XING THE WRONG RWY. SAME BARRICADE ON THE L WERE NOTED PRIOR TO TURN TO CROSS RWY 28. CTLR DID NOT SEEM CONCERNED; PROBABLY BECAUSE THERE WAS NO CONFLICTING TFC. TAXI INSTRUCTIONS WERE CLR BUT DISORIENTATION OCCURRED DUE TO CHKLIST AND PERHAPS ACR B AHEAD TAKING OFF ON RWY 33. SEEMED 'LOGICAL' TO FOLLOW; BECAUSE OF THE INTXN OF 3 RWYS NEAR THAT POINT 'HOLD SHORT INSTRUCTION PROBABLY BETTER THAN 'TAXI TO!' CAPT HAD NOT BEEN TO BWI FOR QUITE A WHILE!