Structure
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. Each deck has it own counterweights, two for the upper and eight for the lower, totaling 9,000,000 lb (4,100 metric tons).
The machinery house is above the upper-deck lift span with an operator's room suspended below the house so that the operator can view river traffic as well as the upper deck. The average daily traffic in 2000 was 23,100 vehicles (including many TriMet buses), 200 MAX trains, 40 freight and Amtrak trains, and 500 bicycles. The construction of the lower-deck walkway connected to the Eastbank Esplanade resulted in a sharp increase in bicycle traffic, with over 2,100 daily bicycle crossings in 2005.
Read more about this topic: Steel Bridge
Famous quotes containing the word structure:
“A committee is organic rather than mechanical in its nature: it is not a structure but a plant. It takes root and grows, it flowers, wilts, and dies, scattering the seed from which other committees will bloom in their turn.”
—C. Northcote Parkinson (1909–1993)
“Communism is a proposition to structure the world more reasonably, a proposition for changing the world. As such, we have to analyze it and, if we deem it reasonable, act upon it.”
—Friedrich Dürrenmatt (1921–1990)
“Women over fifty already form one of the largest groups in the population structure of the western world. As long as they like themselves, they will not be an oppressed minority. In order to like themselves they must reject trivialization by others of who and what they are. A grown woman should not have to masquerade as a girl in order to remain in the land of the living.”
—Germaine Greer (b. 1939)