New West Mission Bay Drive Bridge Opens

The Largest Bridge Replacement in San Diego’s History

On April 4^th, the new West Mission Bay Drive Bridge opened to drivers, pedestrians, and cyclists. The bridge is located on West Mission Bay Drive between Interstate 8 and Sea World Drive, approximately 1.25 miles west of the I-5 / I-8 interchange within the City of San Diego. The Federal Highway Administration (FHWA) Highway Bridge Program (HBP) funded $138 million of the project cost, and the bipartisan Infrastructure Investment and Jobs Act (IIJA) funded $80 million.

The New West Mission Bay Drive Bridge features two new parallel bridge structures with three travel lanes in each direction, along with Class 1 bike paths on both structures.

Originally constructed in the early 1950s to meet the demands and standards of its time, the West Mission Bay Drive Bridge hosted four travel lanes, five-foot-wide sidewalks, concrete pier walls on timber piles, and a concrete median barrier. Sixty-five years later, with the daily traffic volume on the bridge exceeding its current capacity, Caltrans evaluated and classified the bridge as functionally obsolete.

An environmental mitigation plan included 12 acres of wetland restoration to protect avian species and marine mammals.

With Caltrans’ declaration of obsolescence in 2018, the City of San Diego, working in coordination with Caltrans, awarded the contract to Flatiron West, Inc. as the general contractor. The scope of work included replacing the original four-lane bridge with two separate, three-lane structures to create an improved transportation link across the San Diego River.

In order to meet ongoing traffic demands, a unique construction method was used to avoid interrupting traffic along the existing bridge. A temporary construction bridge was built next to the northbound side of the existing bridge to hold the construction equipment needed to build a new three-lane northbound structure.

Crews from Condon Johnson & Associates then drove pipe piles into the ground between the existing bridge and the new temporary construction bridge. With the bridge piers in place, the new bridge deck was constructed on top of them. Nucor Skyline supplied the drilled shaft pipe piles for the bridge foundations.

To see a time lapse animation of the bridge construction, click here: https://www.sandiego.gov/sites/default/files/west_mission_bay_drive_bridge_-_construction_animation_0.mp4

Once the northbound bridge was completed, the temporary construction bridge was removed and then rebuilt along the southbound existing bridge and the process was repeated.

The successfully completed bridge project features:

Two new parallel bridge structures with three travel lanes in each direction;
Class 1 bike paths on both bridges;
Roadway widening and improvements along Sports Arena Boulevard, West Mission Bay Drive and the westbound I-8 off-ramp;
Enhanced architectural features; and
Environmental mitigation for the surrounding wetlands.

The bridge crosses over the San Diego River and a sensitive animal habitat. To protect that habitat, an environmental mitigation plan for the project included 12 acres of wetland restoration at two sites and a noise-abatement program to protect avian species and marine mammals during the construction phases.

Project Partners

Owner: City of San Diego Engineering & Public Works Dept.
General Contractor: Flatiron West, Inc.
Engineer: Rick Engineering Co.
Driving Contractor: Condon Johnson & Associates

Big thanks and a tip of the hard hat go out to Andy Boswell of Flatiron West for his contributions to this story.