H&H led the design engineering team for this movable bridge rehabilitation project. The bridge carries pedestrians, trucks/cars and street cars with an ADT of 33,000 vehicles. The 100+-year-old Broadway Bridge, which spans the Willamette River in downtown Portland, is a rare double-leaf Rall-type bascule bridge and is also on the National Historic Register.
The main project objective is to replace the severely worn wheels and tracks that support the entire weight of this double-leaf bascule structure when the bascule spans are opened to allow for the passage of waterway traffic.
The major element includes replacing the 100-year-old cast steel wheels and tracks with a stronger/modern forged steel design. A temporary shoring and jacking system was also developed to support the two million-plus pound wheel loads so that the wheels can be removed and changed. The project required complex traffic control and extensive coordination with the US Coast Guard and river users. Traffic control measures included maintaining two lanes of traffic (one in each direction and at least one sidewalk at all times of construction. Additionally, one bascule leaf remained operational throughout construction, so smaller vessels could pass. Structural modifications to the truss were also required to accommodate the Rall Wheel installation.
Our design team worked closely with the selected general contractor for 18 months to vet out all project planning, traffic control, public involvement, fabrication, and construction-related issues to provide the greatest value for the available construction budget.
