3.1 miles of bridge does not equal 3.1 miles of on grade highway.  In fact, it’s not even close.  In order to build the new New York Bridge, which is replacing the existing Tappan Zee bridge that crosses the Hudson River, 14 miles of main span cables, 50 miles of foundation pilings, 300 thousand cubic yards of concrete, and 220 million pounds of steel are needed to complete the structure.  Oh, it’s also going to take another 2 years to build, on top of the 3 they’ve already been working on it.