Bridge piers are like icebergs: There's more than you think below the surfaceEvery time you drive by an overpass, you see the cement-and-steel columns that support the roadway.
Bridge piers are like icebergs: There's more than you think below the surfaceEvery time you drive by an overpass, you see the cement-and-steel columns that support the roadway. There could be only a few on a small overpass, or more than a dozen in larger overpasses like the ones atWhat you don’t see is just how low they go.
A typical bridge column drops down about 80 feet underground – about the height of an eight-story building. Each pier includes a cylinder of rebar steel about 6-8 feet in diameter, woven into a lattice that creates hundreds of squares no more than 1 foot across. Each of those squares is tied together – by hand – to strengthen the concrete that is poured on top to create what's known as a caisson .The bridge columns are in place not only to hold the overpass up but to keep it steady. It’s essential that each overpass be held firmly in place.