Article snapshot taken from Wikipedia with creative commons attribution-sharealike license.
Give it a read and then ask your questions in the chat.
We can research this topic together.
The 20th Avenue NE Bridge (also known as the Ravenna Park Bridge) is a three-hinged, steel, lattice-arched bridge that spans a ravine in Seattle, Washington, United States' Ravenna Park. It was designed by Frank M. Johnson under the direction of city engineer Arthur Dimock. Built in 1913, the structure is both listed in the National Register of Historic Places and is a designated city landmark.
The structure is 354 ft (108 m) long. It has a 250 ft (76 m) arch that rises 41 ft (12 m) over the ravine. It supports an 18 ft (5.5 m) reinforced concrete roadway. Beginning on March 11, 1975, a four-month trial began wherein the bridge was closed to vehicular traffic. The bridge did not meet the standards for arterial roads at the time, and upgrading the bridge would have been cost prohibitive. The trial period was successful and the bridge has been closed to vehicle travel ever since, but it is accessible by pedestrians and cyclists.
The newly constructed 20th Avenue NE Bridge (now known as Ravenna Park Bridge), Seattle, Washington, U.S., 1914. Originally a bridge for automobiles, it was eventually pedestrianized.
A person rides a bike over the 20th Avenue NE Bridge.