The American Institute of Steel Construction published a story I wrote for their monthly newsletter’s ” Bridge of the Month” feature. The story follows:
Waddell & Harrington, Consulting Engineers of Kansas City, built many of their patented bridges at many locations throughout the U.S. One example is the Hawthorne Bridge in Portland, OR, spanning the Willamette River. This bridge is configured as several individual spans that connect to the vertical lift span. This bridge truss however, is configured as a “four sheave” design with its counterweights concealed within the vertical, tower trusses. The lift span is 250 feet long, and can raise 110 feet for a total clearance of 160 feet above the river. Cables carry two 424-ton counterweights that are adjusted for tension with turnbuckles. The lift span is operated by two 125 hp motors.
The Hawthorne Bridge has been described as the oldest extant example of this type of a four sheave vertical lift bridge in the U.S.
Credit:
Darrel G. Babuk, AIA, MRAIC is an architectural historian who specializes in presentations of early industrial age structures. His presentation topics may be seen at www.learnaboutchicago.com.
Image 1: Photo from Library of Congress, Prints and Photographs Division, Historic American Buildings Survey or Historic American Engineering Record, Reproduction Number HAER ORE, 26-PORT, 10-8.
Image 2: Photo from Library of Congress, Prints and Photographs Division, Historic American Buildings Survey or Historic American Engineering Record, Reproduction Number HAER ORE, 26-PORT, 10-23.
As a sidenote, Waddell and Harrington designed and built several “Center Lift Span” bridges in the Chicago area, including the Pittsburgh, Fort Wayne & Chicago Railway, Calumet River Bridge, (1912 – 1913) and the Pennsylvania Railroad Bridge at 18th and Stewart Street (1910).