Long Beach International Gateway Bridge

The gateway to an American economic centerpiece is as architecturally striking as it is crucial to daily commerce in Southern California.

About 15% of all North American maritime container traffic crosses the Long Beach International Gateway Bridge, and freighters pass under it when entering the Port of Long Beach’s back piers. It’s a critical infrastructure link and a vital component of the regional and national economy.

The new bridge is also a landmark of a city best known for its port--and a first-of-its-kind bridge in the state.

The $1.5 billion, 9,996-ton bridge opened in 2020, replacing the 51-year-old Gerald Desmond Bridge that carried six lanes of Interstate 710 over the port’s back channel. The replacement project didn’t just create a bridge designed to last 100 years and secure long-term port access. It birthed California’s first major cable-stayed bridge and an aesthetically pleasing addition to Long Beach’s waterfront cityscape. It also pushed the envelope of seismic design for bridges.

In 2011, the Gerald Desmond Bridge had been open for 43 years, was seismically deficient, and exceeded its useful life. The Port of Long Beach—in partnership with the California Department of Transportation (Caltrans), the Federal Highway Administration, and Los Angeles Metro—invited several teams to provide design-build bids for a replacement project, which included replacing the main span bridge, overhauling the bridge’s elevated approach structures, and rebuilding the major freeway interchanges that feed them.

Caltrans and the port expected the replacement bridge would be a two-tower, six-lane cable-stayed bridge with a 100- year service life, providing seismic resilience and adequate vertical and horizontal clearance to accommodate the newest generation of cargo ships—all within an affordability limit. Steel provided a lightweight superstructure for an economical and innovative approach to seismic design.

The final product is a 2,000-ft-long by 150-ft-wide bridge fabricated from A709 HPS-50W plate. It has fracture critical elements, trapezoidal box edge girders, I-beam floor beams, complex box end girders, pier skin plates, and cable stayed anchor boxes. A 2,000-ft bike and pedestrian structure cantilevers off the south end.

Trusted Towers

The owner mandated a tapered mono-pole tower after an architectural study of form and proportion involving a world-renowned bridge architect. The design-build team responded to the architectural vision by designing a unique tower form that tapers from an octagon to a diamond. The tower design emerged from aesthetic, constructability, and seismic performance considerations.

The 515-ft-tall mono-pole towers support the 1,000-ft main span. The non-redundant towers must remain undamaged in the 1,000-year seismic design event, with a peak spectral acceleration of 1.4g. Those requirements are met by an array of seismic dampers that isolate the superstructure from the substructure, allowing 32 in. of movement in any direction.

The towers are designed to be extremely flexible, allowing the top to displace more than 8 ft in the design event, with peak strains remaining well below essentially elastic limits. Layers of beyond-design- basis performance were provided, including ductile detailing, capacity protection, provision of structural stops to protect dampers, capacity protection, and explicit analysis of 125% of design ground motions.

The octagonal tower geometry successfully merges two occasionally competing objectives: construction efficiency and aesthetic distinction. To facilitate an efficient jumping formwork system for the towers, only four of the eight sides were tapered, meaning half of the vertical formwork components remained unchanged with each jump. The tapered faces are orthogonal to the bridge’s primary axis.

Keeping the diagonal faces constant resulted in a diamond geometry, simultaneously resolving the geometric conflict between cable stays and the section corners and creating a unique and instantly recognizable tower form. The octagon-to-diamond solution uses light and shadow to identify the structure’s unique design while facilitating optimized construction methods and structural performance. Seismic detailing drew upon prior research into seismic design of concrete chimneys to understand behavior of tall hollow reinforced concrete cantilevers in high seismic zones.

The faceted shape combines elegance with economy, and the light and shadow interplay creates definition. Box girder approaches provide for clean lines, and the tall, slender columns respond to the shape of the tower with architectural column flares to articulate the connection between the substructure and the superstructure. A dramatic aesthetic lighting scheme brings the bridge to life at night.

An innovative moveable scaffold system (MSS) allows long spans at high elevation while avoiding utility constraints. The double Texas U-turn on land eliminated two flyover ramps, cutting costs and returning valuable real estate to the port. Foundation savings were also found through an innovative manchette tube tip grouting system.

A Seismic Superstar

To achieve the extreme seismic requirements of the site with a cable-stayed structure, the bridge towers and end bents feature a unique design to remain essentially elastic during seismic events. The bridge deck is isolated from the towers and end bents by 34 structurally fused viscous hydraulic dampers, which activate only during major seismic events. After the fuse is released, the viscous dampers dissipate the energy of the quake.

The unique seismic design reduces maintenance requirements for the port, ensuring uncompromised performance during the design-basis seismic event and improved life cycle resilience. Fuses and dampers were designed with the port’s resilience concerns at the forefront, featuring integrated pressure gauges, observation windows, and transducers to facilitate routine maintenance. The dampers were further optimized to make their size manageable for installation or replacement by the contractor. Towers and end bents were also simplified to contain fewer items to inspect and maintain, improving constructability and cost efficiency.

Taylor Devices International (TDI) in Buffalo, N.Y., supplied and manufactured the dampers, which have a force capacity of up to 884,000 lb and a mid-stroke length of up to 20½ ft. The dampers underwent a rigorous prototype and production testing program at TDI’s facility and at the University of California San Diego.

Post-seismic inspection and resetting were critical to the design. Comprehensive access facilities have been included with the bridge and were designed to accommodate the full range of seismic movements so maintenance personnel can easily access any damper after an earthquake.

Tell-tales on the dampers will indicate whether the fuse has activated, and jacking positions are provided in the bridge to facilitate recentering and replacement of fuses. The bridge allows for full traffic even after fuses have been activated, with no disruption during post-seismic inspection and fuse replacement.

A comprehensive and strong motion monitoring system with accelerometers on the bridge and ground facilitates evaluation of earthquake events for bridge operation and research purposes.

Community Impacts

The innovations introduced to the project directly translate into material savings, which reduced the carbon footprint. The double Texas U-turn alone saved approximately 5,000,000 kgCO2e and avoided environmental risks associated with installing deep foundations through a known hydrocarbon contaminant plume near the proposed flyover structure.

The U-turn was part of the traffic engineering plan that reduced physical infrastructure while still achieving the required functionality, significantly reducing local environmental impacts and embodied carbon. Environmental impact reduction also came from the long spans of the approach bridges and the selection of the MSS construction method, which minimized the disturbance to the ground.

The bridge is not exclusively for cars. The 1.5-mile-long Mark Bixby Memorial Bicycle Pedestrian Path along the south side offers spectacular views of the San Pedro Bay, the port, and much of the city’s coastline. The path is named after one of Long Beach’s leading bicycle advocates, Mark Bixby, who helped create the city’s Bicycle Master Plan and founded the Long Beach Bicycle Festival. He also spearheaded the successful grassroots effort to include a bike path in the design of the new bridge.

Active public engagement throughout construction led to substantial community involvement and awareness, including a highly active social media campaign and regular public tours of the site. The community has welcomed the bridge and gave it a new name, the Long Beach International Gateway Bridge, by public vote.

Project Team

• Owner: California Department of Transportation, Sacramento, Calif.

• Owner’s representative: Port of Long Beach, Long Beach, Calif.

• General contractor/erector: SFI (Shimmick/FCC/Impregilo) JV, Irvine, Calif.

• Structural engineer: Arup, New York

• Steel team:

  • Fabricator: Stinger Bridge & Iron, Coolidge, Ariz. *AISC full member; AISC-Certified fabricator and erector*

  • Detailer: SSP Engineering, Queen Creek, Ariz. *AISC associate member*