NY bridge height,
1. NY's general rule of thumb is, If the bridge height says 12'6" it is actually 13'6".
2. If the sign say "Actual Clearance" 12'9" Then that bridge is that actual height. 12'9" not 13'9".
Why I dont know, but when I was on 278 in NYC I saw a sign that said 12'2" and I flew right under it. NY definitly needs to change their sign without a doubt.
Use those rules as general rules of thumb.
Hope that makes sense.
And...........
Welcome to the Empire State......