Tower Bridge, Sacramento

Approaching downtown Sacramento from West Sacramento, it's hard to miss the eye-catching Tower Bridge. The vertical lift bridge was opened to traffic in 1935. It replaced the original M Street Bridge, which at only about 25 years old was already causing concerns with traffic congestion. The old bridge had become inadequate as Sacramento's population and automobile traffic increased dramatically, while its swing span also caused delays and restricted river navigation.

The 209-foot-long lift section of the bridge weighs around 2.3 million pounds. Together with its counterweights, cables, and associated equipment, the total moving load is about five million pounds. Still, the clever use of balanced counterweights means that relatively little power is required to operate the bridge. When the bridge is up, it provides 100 feet of vertical clearance above high water for vessels sailing up the Sacramento River. The towers are 160 feet tall and stand on concrete foundations sunk to a depth of about 50 feet below the water surface.

The bridge's paint scheme has been changed several times over the years. The present metallic gold color, chosen by a local vote in 2002, replaced the yellow-ochre finish applied in the 1970s. More than 43,000 people took part in the vote, with the all-gold option receiving 48 percent.