Portland Milwaukie Light Rail bridge: First transit-only cable-stayed bridge offers unique capacity for shared use

Abstract

Tri-County Metropolitan Transportation District (TriMet) of Oregon is extending transit service from Portland State University to Milwaukie. As part of this extension, TriMet is constructing a cable-stayed bridge across the Willamette River. When completed, the Portland Milwaukie Light Rail (PMLR) Bridge will be the first transit-only cable-stayed bridge built in the United States and will include capacity for light rail, buses, bicycles, pedestrians, and streetcars in the future. The crossing features a 524 m (1,720 ft.) bridge with a 238 m (780 ft.) main span. A unique aspect of the PMLR Bridge is the sharing of the bridge by light rail transit and pedestrians. A rolling stock analysis was performed to ensure pedestrian comfort during dynamic excitation of the bridge from transit vehicles. A synchronized lateral excitation investigation further ensured pedestrian comfort under the condition of full pedestrian access across the entire bridge during special occasions when the bridge will be closed to transit vehicles.