ACR LGT FOLLOWED WRONG TXWY AND CROSSED ACTIVE RWY WITHOUT CLRNC.

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PRIOR TO THE BEGINNING OF THIS PARTICULAR ROTATION; THE CAPTAIN REQUESTED WE ADHERE TO COCKPIT STERILITY DURING TAXI AS WELL AS OTHER PHASES OF FLIGHT. HE EMPHASIZED THAT THERE WILL BE NO READING MATERIAL IN THE COCKPIT OR IN OUR FLIGHT KITS. NOTHING WAS THERE TO PROVIDE ANY OUTSIDE DISTR FROM OUR DUTIES. THE COCKPIT DURING TAXI WAS STERILE. I AM A FAIRLY NEW FIRST OFFICER ON AN LGT AFTER 8 YEARS AS FLIGHT ENGINEER. I HAD NOT BEEN TO BOSTON LOGAN IN A FEW YEARS. IT WAS NIGHT AND I HAD A SMALL PROBLEM FIGURING OUT WHERE WE WERE TAXIING. SO; I PULLED THE TAXI CHART OUT AND CLIPPED IT TO THE CONTROL YOKE. THE CAPTAIN; USED TO FLY OUT OF BOSTON; WHILE PREVIOUSLY BASED THERE. I THEREFORE ASSUMED HE KNEW WHERE HE WAS GOING; AND IF HE WASN'T SURE; I HAD MY CHART RIGHT THERE AND HE COULD ASK ME FOR HELP OR DIRECTION. (BAD ASSUMPTION...) WE WERE CLRED TO TAXI TO 33 ON CHARLIE; HOLD SHORT OF 27. WE'RE TAXIING DOWN CHARLIE. I LOOKED DOWN AT MY CHART AND THE TWR CLRED US TO CROSS 27. AS I READ BACK THE XING CLRNC; I LOOKED UP AND THERE WAS A LIGHTED RUNWAY (THEY WERE DEPARTING ON BOTH 27 AND 33) RIGHT IN FRONT OF US; AND A YELLOW RECTANGULAR SIGN ON THE SIDE OF THE TAXIWAY WITH 27 CLIMBING TO ON IT. LOOKING OFF TO THE RIGHT; THERE WERE 3 ACFT LINED UP FOR FINAL; EVENLY SPACED WITH ABOUT 3 TIMES AS MUCH ROOM BETWEEN THE THRESHOLD AND FIRST ACFT THEN SPACING BETWEEN THEM (LEAVING THE APPEARANCE THAT THERE WAS A GAP WHICH IS WHY GND CLRED US TO CROSS). THE CAPTAIN ADDED POWER AND ACROSS WE WENT. WE CROSSED RUNWAY 33. WE SHOULD HAVE TURNED TO THE RIGHT AND PARALLELED 33; XING 27 ALONG THE WAY TO THE DEPARTURE END OF 33. THE 27 CLIMBING TO SIGN WAS ACTUALLY TELLING US TO CONTINUE ALONG THE TAXIWAY TO GET TO 27--NOT THIS IS 27 RIGHT IN FRONT OF YOU. INACTIONS: I SHOULD HAVE KNOWN EXACTLY WHERE WE WERE. WE WERE NOT WHERE I THOUGHT WE WERE EXACTLY. I SHOULD HAVE WATCHED CLOSER. HOWEVER; I DON'T FEEL I SHOULD HAVE TO BE WATCHING A CAPTAIN LIKE A HAWK. THAT IS WHAT HE IS THERE FOR. I SHOULDN'T ASSUME HE'LL ASK IF HE DOESN'T KNOW WHERE HE IS GOING. I HAD THE FURTHER ASSUMPTION THAT HE WAS INTIMATELY FAMILIAR WITH THE AIRPORT SINCE HE USED TO BE BASED OUT OF THERE. ANOTHER LESSON LEARNED WITHOUT HURTING ANYONE... EVEN PLAYING BY THE RULES DOESN'T PREVENT MISTAKES. SUPPLEMENTAL INFORMATION FROM ACN 96535: THE GND CONTROL FREQ WAS JAMMED AND HARD TO CLARIFY INSTRUCTIONS DUE TO CONGESTION. THE TAXIWAY SIGNS AND LIGHTS WERE DIRTY; NON-ILLUMINATED AND IN GENERAL HARD TO SEE. WE WERE CLRED TO CROSS 27 TO GET TO 33L. WE USED TAXIWAY C AND DUE TO A MISUNDERSTANDING; CROSSED 33L (GOING TO CROSS 27 AND THEN VIA A CIRCUITOUS ROUTE BACK TO 33L FOR DEPARTURE.