HVY LGT USED A WT RESTRICTED TAXIWAY AT BHM.

Narrative

UPON TAXI OUT FROM RAMP (LOCATED ON NE TIP OF TERMINAL) WE REQUESTED RWY 23 FOR DEP. CURRENT WX HAD WIND AT 040 DEG AT 4 KTS; RWY 5 IN USE; WE WERE CLRED TO TAXI TO RWY 23 FOR DEP. WE THEN ASKED GND FOR SPECIFIC TAXI INSTRUCTIONS; AND ASKED IF WE SHOULD TAXI TO RWY 23 VIA TAXIWAY N AND TAXIWAY G. GND CTL THEN ASKED US IF WE REQUIRED THE FULL LENGTH OF RWY 23 FOR DEP. WE RESPONDED THAT WE DID REQUIRE FULL LENGTH FOR DEP. THEN GND SAID OK THEN TAXI TO RWY 23 AS REQUESTED; IMPLYING TO US TO TAXI VIA TAXIWAY N AND G. UPON APCHING RWY 23 TO HOLD SHORT WE REALIZED THE NOTE ON THE TAXIWAY DIAGRAM THAT INDICATES TAXIWAY N RESTR TO ACFT WEIGHING 50000 POUNDS OR LESS. WE WERE THEN CLRED FOR TKOF; AND RESUMED A NORMAL FLT. THERE WAS NO SUBSEQUENT CORRECTIVE ACTIONS ABLE TO BE MADE. CAUSE OF PROBLEM: 1) DID NOT SEE NOTE ON ARPT DIAGRAM WARNING ABOUT TAXIWAY N'S WT RESTRICTION. 2) GND CTL DID NOT ADVISE US AS TO WHICH WAY TO TAXI TO RWY; OR ADVISE ABOUT TAXIWAY N'S WT LIMIT. PREVENT RECURRENCE: 1) TRY TO EXAMINE AND READ ARPT DIAGRAM MORE CLOSELY. 2) INSIST UPON BETTER TAXI INSTRUCTIONS FROM GND CTL (IT WAS MY FIRST TIME AT BHM). CONTRIBUTING FACTORS: 1) FIRST TIME BHM; AL. WAS NOT FAMILIAR WITH NORMAL TAXI RTES. 2) WAS READING ARPT DIAGRAM IN DIMLY LIT COCKPIT USING A MAP READING LIGHT. P.S. THE WAY THAT TAXIWAY N IS INDICATED BY AN ARROW COULD SUGGEST THAT TAXIWAY NM; E OF TAXIWAY G; IS THE ONLY PORTION THAT HAS A WT RESTRICTION. THAT COULD BE UP TO INDIVIDUAL INTERP.