ACR MLG TAXIING WITHOUT CLRNC; CROSSED THE HOLD LINE FOR AN ACTIVE RWY.

Narrative

AFTER LNDG AT JFK ON RWY 22L; WE EXITED ON THE HIGHSPD TXWY AT J AND THE TWR CTLR GAVE NO INSTRUCTIONS (CONCERNING TAXI; SWITCHING TO GND FREQ; ETC). CONSTRUCTION PREVENTED CONTINUING ON TXWY J; AND; STILL WITH NO INSTRUCTIONS FROM THE TWR; WE TURNED ONTO TXWY Z; TOWARD RWY 13R/31L. THE LAST 1000 FT OF RWY 13R WAS NOTAMED CLOSED ON OUR FLT PLAN; AND THE ATIS HAD SAID RWY 13L/31R WAS CLOSED. I ALSO (MISTAKENLY) HAD THOUGHT THE ATIS BROADCAST HAD INCLUDED RWY 13R/31L IN THE RWY CLOSURES. I POINTED OUT RWY 13R/31L TO THE CAPT; ASSUMING WE WOULD STOP AND HOLD SHORT UNTIL HEARING SOMETHING FROM THE TWR. I WAS THEN DISTRACTED AS I LOOKED DOWN; STUDYING THE ARPT DIAGRAM TO SEE IF THERE HAD BEEN ANOTHER TAXI RTE. AS I LOOKED BACK UP; WE HAD CROSSED THE HOLD SHORT LINE FOR RWY 13R/31L AND ANOTHER PLANE WAS HOLDING IN POS FOR DEP ON RWY 13R. I POINTED OUT THE PLANE TO THE CAPT WHO THEN REALIZED THAT WE WERE APCHING AN ACTIVE RWY. SIMULTANEOUSLY AS HE BRAKED; I ASKED TWR IF WE WERE CLRED ONTO RWY 31L FOR TAXI (THAT PORTION WAS THE 1000 FT THAT WAS NOTAMED CLOSED) OR IF HE WANTED US TO SWITCH TO GND. HE THEN CLRED US TO TAXI DOWN RWY 31L AND EXIT ON RWY 4L/22R AND THEN CONTACT GND. CONTRIBUTING FACTORS INCLUDED: THE CONSTRUCTION RIGHT AT THE HIGHSPD TXWY AS WE EXITED; WHICH HAD NOT BEEN ON THE ATIS OR NOTAMS. ALSO; OUR LACK OF FAMILIARITY WITH THE AIRFIELD. ALSO; THE CTLR'S LACK OF INSTRUCTIONS WHEN WE EXITED THE RWY AFTER LNDG. ALSO; MY DISTR AS WE APCHED THE RWY 31L HOLD SHORT. ALSO; THE CAPT'S CONFUSION THAT WE WERE APCHING A RWY (31L) AND NOT ANOTHER TXWY. IT HAPPENED SO QUICKLY THAT I WAS ALSO CONFUSED IF THE CAPT HAD CONTINUED TAXIING BECAUSE OF THE NOTAM AND ATIS BROADCAST CONCERNING RWY CLOSURES. THE BOTTOM LINE IS STILL THAT WE SHOULD HAVE STOPPED AND HELD OUR POS UNTIL QUESTIONING TWR.