California’s First Major Vehicular Cable-Stayed Bridge

Construction of the Gerald Desmond Bridge Replacement Project (GDBRP) in Long Beach, California, has recently been completed. The new bridge is located at the Port of Long Beach and consists of approximately 2.6 km of bridge structure. The approach spans are made up of conventional cast-in-place box girders, while the main span over the Back Channel includes California’s first major vehicular cable-stayed bridge. This signature structure has a 304.8 m main span and 152.4 m back spans. Now that it has been built, the new bridge is the second-tallest cable-stayed bridge in the US, and has the highest vertical clearance of any cable-stayed bridge in the country. The replacement bridge is founded on a total of 352 cast-in-drilled-hole piles that range in size from 1.8 to 2.4 m in diameter. More than 100 reinforced concrete columns of varying heights support the superstructure, with the two towers supporting the main span featuring a hollow 156.9 meter-tall monopole design. The signature cable-stayed bridge span consists of a pair of 1.8 m deep steel edge girders with a box shape cross-section. Framing into the edge girders are variable-depth steel floorbeams with four lines of longitudinal stringers spanning between them. This floorsystem supports the full-depth precast concrete deck panels. The cross-section of the bridge has an out-to-out width of approximately 47.5 m to accommodate three lanes in each direction and emergency lanes on both sides (3.0 m shoulders). Seismic demands on the main span are dissipated with passive dampers at the towers and end bents. The superstructure of the low-level approach spans was built using conventional falsework; however, the high-level approaches were built using a movable scaffolding system (MSS). This project is the first time in the State of California that an MSS was used to build bridge superstructure elements. The MSS had a self-weight of 1.41 million kg. With the load from the concrete, the MSS bore approximately 3.2 million kg, supported by brackets mounted onto the columns. The main-span superstructure was stick-built with help from stiffleg derrick cranes on the deck, and two 178.3 m tall tower cranes, which were the tallest tower cranes currently in use at the time on any infrastructure project in the US. This paper will provide a general overview of the project from the program manager/construction manager perspective, and describe some of its key design and construction innovations and challenges. In addition, design-build lessons learned during the construction phase will be summarized.