Could someone please describe how bad of a climb these bridges in NYC really are?

I mapped out the manhattan bridge as a route on www.mapitpronto.com and don't see any big deal. But I don't think the elevation data includes the bridge itself (only land). How much of a climb are the bridges? How steep of a climb are the bridges?

The following link shows the ride I mapped out:
www.mapitpronto.com

(just enable the elevation graph at the bottom of the page) It goes all the way to 0 feet, but I think that is because the elevation data only includes land and not the bridge.

In any case, I try my best to stay in my 3rd ring, I only drop to my second ring when absolutely necessary. Granny, out of the question.... unless I'm dead. I have used the granny maybe 3 or 4 times this summer tops in 1600 miles of riding. I'm guessing that I'm probably not being as efficient as I could because I definately have a mental block. Stay off the granny.... Stay off the granny.... Are there any good sites out there that describe how best to use your gears?