Project Overview – Murray Morgan Lift Bridge
Location: Tacoma, Washington
Client: City of Tacoma
Hardesty & Hanover is the Engineer of Record for the rehabilitation of the Murray Morgan Bridge with General Contractor, PCL Constructors, Inc. This Design-Build project utilizes a combination of Local and Federal Funds with a cap on the maximum bid value ($47M). This required our team to focus on innovative ways to meet the project goals, while being cost effective in design and construction.
The bridge, designed by Hardesty & Hanover’s predecessor firm Waddell & Harrington in 1913, was placed on the National Register of Historic Places in 1982. Over the decades, Hardesty & Hanover has serviced the bridge, helping to keep the nearly 100-year-old structure safe for both the traveling public and waterway user.
Located at 11th Street over the Thea Foss Waterway, the bridge has a total length of approximately 1760 feet, and comprises three segments – the south approach, a multi-span steel girder structure built in 1913; the north approach, a multi-span concrete girder structure built in 1954 as a replacement to the original approach structure; and a three-span, steel through-truss main river section with a vertical-lift center span.
The structural rehabilitation was broken into three sections, the Main Truss; the Port Approach Spans and the City Approach Spans. To return vehicular traffic to the bridge without load restrictions, the project requires conversion of the bridge from four lanes to two lanes of traffic with two lanes being changed to bicycle and pedestrian lanes. Hardesty & Hanover performed structural rehabilitation design for the two through trusses, the through truss lift span, and the lift towers to be performed, removing the existing cantilevered sidewalks on these three trusses.
The four-counterweight sheave assemblies (counterweight sheaves, trunnion shafts and support bearings) will be replaced. Our team developed a unique concept design to incorporate spherical roller bearings into the counterweight sheave assemblies minimizing project costs and structural modifications. Extensive electrical systems work was required for the movable span and the bridge overall. The project will remove and replace the existing power rail system; upgrade the vehicle traffic control system; provide for a new bridge electric drive, power and control systems (including better emergency provisions).