The Steel Bridge is a through truss, double-deck vertical-lift bridge across the Willamette River in Portland, Oregon, United States, opened in 1912. It is the only double-deck bridge with independent lifts worldwide and the second oldest vertical-lift bridge in North America, after the nearby Hawthorne Bridge.

The bridge was completed in 1912 and replaced the Steel Bridge that was built in 1888 as a double-deck swing-span bridge. It opened in July 1912 to rail traffic and on August 9, 1912, to automobiles.

The lift span of the bridge is 211 feet (64 m) long. At low river levels, the lower deck is 26 feet (7.9 m) above the water, and 163 feet (50 m) of vertical clearance is provided when both decks are raised. Because of the independent lifts, the lower deck can be raised to 72 feet (22 m), telescoping into the upper deck but not disturbing it. 

The machinery house sits atop the upper-deck lift truss. The operator’s room is suspended from the top of the lift-span truss, directly below the machinery house, so that the operator can view river traffic as well as the upper deck. After the 2001 addition of a pedestrian walkway on the lower deck, cameras, and closed-circuit television monitors were added to allow the operator to view the lower deck walkway.

According to en.wikippedia. Source of photos: internet