When South Nyack, N.Y., Mayor Bonnie Christian rode her bike as a child across the Tappan Zee Bridge at its grand opening more than six decades ago, she had little idea she would one day witness construction of the $4-billion, 3.1-mile structure that would replace it. “You personally never thought of a time span on it,” she says.
The New York State Thruway Authority’s ambition is for the new two-span bridge crossing the Hudson River 25 miles north of New York City to have a 100-year useful life—so the South Nyack mayor who welcomes the next bridge probably isn’t even born yet.
Because it can moderate the damaging effects of earthquakes, base-isolation is a technique used primarily in seismically active regions. ENR takes a look at some of the largest applications of base-isolation technologies in the world.