20th Avenue NE Bridge, Steel arch bridge in Ravenna Park, Seattle, United States

The 20th Avenue NE Bridge is a three-hinged steel lattice-arched bridge spanning a ravine in Ravenna Park. It is 354 ft (108 m) long, with a 250 ft (76 m) arch rising 41.5 ft (12.6 m) from its footings. The bridge carries an 18 ft (5.5 m) reinforced concrete roadway and a 5 ft (1.5 m) sidewalk.

Designed by Frank M. Johnson under city engineer Arthur Dimock, the bridge was built in 1913. It was listed on the National Register of Historic Places and is also a designated Seattle city landmark. A four-month trial closure to vehicles began on March 11, 1975, and the bridge has remained pedestrian and cyclist only since.

The bridge is a designated Seattle city landmark as well as a National Register listing. Its popular name, Ravenna Park Bridge, ties it to the ravine it crosses. Since the 1975 closure to cars, pedestrians and cyclists have used the deck as a car-free route through the park.

The bridge has been open to pedestrians and cyclists since 1975 and provides a direct link between residential neighborhoods. The path through the natural area is straightforward to use and accessible for various visitors.

The structure uses a three-hinged steel design that achieves maximum stability with minimal materials. This thoughtfully engineered system from 1913 allowed a lean structure to be built that continues to perform well today.