The Broadway Bridge structure totals 1,613 feet in length and consists of three westerly approach Pennsylvania-Petit Through truss spans of 270 feet, 286 feet and 297 feet, a 278-foot double-leaf Rall bascule main channel draw span, and one Pennsylvania-Petit Through truss of 297 feet and one Warren Through truss of 185 feet on the eastern approach.
The bridge was constructed in 1911 and 1912. The bridge currently carries four lanes of traffic with an average daily volume of 30,000 vehicles. The overall width of the structure is 70 feet. Vertical clearance of the closed bascule span is adequate for the majority of river traffic, with openings necessary about 25 times per month, primarily to accommodate grain terminal ships.
The Broadway approach ramp on the west side is a combination of structures built in 1911 and 1927. The first 456 feet is a concrete roadway slab with retaining walls, originally 67 feet wide but later widened to 85 feet in 1927. The next 331 feet consists of six spans made up of a concrete deck supported by steel girders, floorbeams, stringers and columns. This section is connected to a steel Viaduct Intersection, which is 282 feet long, has four variable length steel girder spans, and connects the approach to the bridge structure. The Lovejoy Street approach ramp was originally constructed in 1927. This approach was recently torn down by the City of Portland and rebuilt as a shorter approach in order to allow for development of the new River District residential area.
The east approach to the bridge is a two-span continuous concrete deck girder bridge 84 feet long crossing over Interstate Avenue. The end abutment walls are approximately 20 feet high.
A very complicated bridge
Commuters sitting in traffic complain that Broadway openings take longer than other movable bridges. They're right. Average opening times for Morrison, Burnside and Hawthorne bridges run from five to eight minutes. On the Broadway, openings can take 20 minutes and longer. One reason for the delays is that Broadway is a very complicated drawbridge. Called a double-leaf bascule (means seesaw in French), the weight of the deck, or leaf, is balanced by a counterweight. Portland's two other bascules, Morrison and Burnside, have counterweights hidden out of sight inside their piers. Not the Broadway, however. Broadway's two counterweights are located above the bridge's deck. The Broadway bascule span is an unusual Rall-type bascule, invented by Theodore Rall. On this bridge, each leaf and its counterweight roll back and forth on giant bull wheels to allow maximum river clearance. Only three Rall-bascule highway bridges still exist in the U.S., the other two being much smaller than the Broadway. The bridge's draw span is unusually long. Each leaf measures about 140 feet, weighing more than 2,000 tons, making Broadway the seventh longest bascule bridge in the world.
The overall Broadway Bridge was designed by Ralph Modjeski of Chicago, IL. The bascule span was designed by the Strobel Engineering Company of Chicago, holder of the Rall patent. The Union Bridge and Construction Co. of Kansas City, MO constructed the substructure and the Pennsylvania Steel Co. of Steelton, PA fabricated and erected the steel and bascule spans. In 1927, another famous bridge engineer, Gustav Lindenthal of New York, designed part of the Lovejoy Street ramp as well as modifications to the truss spans.