The Wallis Annenberg Wildlife Crossing on U.S. Highway 101 in Los Angeles, funded by various organizations, aims to protect biodiversity and reconnect wildlife habitats. Caltrans reports substantial progress in construction, with completion expected in 2026. The design includes sound walls, darkened areas and high fencing to guide wildlife and minimize impacts from traffic. C.A. Rasmussen oversees the project with a large fleet of equipment and dedicated teams to ensure steady progress.
Caltrans photo
The first girder on the Wallis Annenberg Wildlife Crossing is lowered into place.
After years of planning, C.A. Rasmussen Inc. has made significant progress on the construction of the Wallis Annenberg Wildlife Crossing on U.S. Highway 101 in Los Angeles County.
It's a $90 million project that the California Department of Transportation (Caltrans) is building, and various environmental organizations are financing.
Caltrans awarded a contract to C.A. Rasmussen with money provided by sources including the Annenberg Foundation ($25 million), the California Wildlife Conservation Board ($25 million), the state of California ($20 million) and other grants and private donations.
One of the main reasons for the initiative is to protect biodiversity, emphasizing the mountain lions/pumas that reside in the area. The life of a male mountain lion, P-22, who lived in the urban Santa Monica Mountains in Los Angeles, highlighted the need for the bridge to ensure that the local population would have access to the genetics of species on the opposite side of the highway. That population was essentially isolated by major highways.
"Caltrans is pleased with the progress of this project," Caltrans Public Information Officer Michael Comeaux said in late October. "Construction is substantially complete for the reinforced concrete structure including the bridge deck which spans this very busy freeway. This will reconnect wildlife habitat on both sides of the roadway and restore an essential natural corridor for wildlife to survive and thrive."
The current structure is Stage 1 of the project (the crossing over the freeway, U.S. Highway 101 or the Ventura Freeway).
"In Stage 1, we have placed more than 13,447 tons of structural concrete — that's more than 26.9 million pounds," Comeaux said. "The concrete is reinforced with more than 1,082 tons of rebar, equal to more than 2.1 million lbs. In Stage 2, we anticipate using larger quantities of both concrete and bar reinforcement than are used in Stage 1. Stage 2 will involve utility relocation, construction of the crossing over Agoura Road — a city street parallel to the freeway — and significant earthwork. Stage 2 is expected to go out to bid in the near future."
In the first stage, a waterproofing layer is being installed on the bridge deck. Next, a drainage system and an aggregate base layer will be placed on the bridge deck.
"At this time, soil is being prepared — one might say the soil is being curated or cultivated — and will be placed on top of the bridge deck starting late this year, approximately," Comeaux said. "Vegetation that will be planted in the soil has been grown in a nursery near the project site. The plants grew from seeds that were collected within a 5-mi. radius of the project site. As a result of this process, the vegetation on the crossing will be ideally suited to the location. The goal is to create a vegetated bridge deck that is a living part of the natural wildlife habitat on both sides of the freeway."
The construction phase of the bridge project began in spring 2022. Completion of both stages is expected in 2026.
A Caltrans construction advisory in September illustrated the progress.
"Crews are constructing sound walls and concrete barriers on the wildlife crossing above traffic lanes," it stated. "Crews are removing temporary supports [steel beams, timber posts and diagonal bracing] next to traffic lanes under the wildlife crossing."
Comeaux is pleased that wildlife is already aware of the project, explaining how an owl was among the first customers.
"This part of U.S. Highway 101, also called the Ventura Freeway at this location, is one of the busiest freeways in Los Angeles County," he said. "It is used by about 300,000 vehicles a day, on average. Scientists and researchers report that traffic noise and bright illumination from vehicle headlights at night are deterrents to the movement of wildlife. In 2024, while girders were being placed above the traffic lanes — which created a large, darkened area over the freeway — an owl was seen flying over the wildlife crossing, which is believed to be the first known instance of wildlife crossing over the still-unfinished Wallis Annenberg Wildlife Crossing.
"The project employs methods, such as sound walls, to dampen traffic noise to create a quiet crossing over the freeway," he added. "Also, the project design includes methods to reduce the impact of artificial lighting on wildlife. For example, the roadway lighting provided for motorists will have a lower color temperature than is normally used at a highway bridge. Also, the pigment in the concrete used for this crossing gives the concrete a darker shade to reflect less light which will help darken the area of the crossing at night, further reducing the impact on wildlife."
Fencing 12 ft. high will be installed along both sides of the freeway to guide wildlife to the crossing. The fencing is an essential element of the project. A convenient observation point will be constructed nearby to enable in-person viewing by visitors who wish to see the crossing in use.
"Caltrans and the state of California place high importance on reducing impacts on wildlife from the state transportation system," Comeaux said. "Caltrans has taken meaningful steps to enhance wildlife corridors in California and plans to continue doing so."
The bridge was designed by a variety of state agencies, including Caltrans.
"The weight of the completed crossing will include a layer of gravel, topped by a layer of soil — roughly three feet of soil on average, though the soil depth will vary between approximately one foot and four feet deep at various locations on the bridge," Comeaux said. "The bridge is 174 ft. wide, and it is 210 ft. long. It crosses eight traffic lanes, plus entrance/exit lanes which run between successive interchanges. Therefore, the bridge crosses 10 lanes of pavement. The bridge is wide enough that if it had been designed for vehicles, it could accommodate five or six lanes in each direction, depending on their configuration."
Forty-one girders span the southbound lanes of the freeway, stretching from the southern abutment to the median; another 41 girders span the northbound lanes. After those girders were placed, concrete was placed on top of them to construct the bridge deck.
Dave Dubois, C.A. Rasmussen's project manager and an experienced bridge builder, is elated to be constructing a bridge for wildlife.
"Temporary support during construction of the bridge was a challenge," he said. "One hundred board ft. of lumber was placed along with over 11,000 ¾-inch bolts to temporarily support the structure during construction."
Dubois said the construction process is rigorous and methodical.
"We started the project by installing shoring for the abutments," he said. "Once the abutments were complete, we built the center bent consisting of 10 concrete columns varying in height from 20-25 feet. We placed 82 precast concrete girders on the abutments, with the center bent weighing 60 tons each and over 100 ft. in length. We used a 500-ton crane to set each individual girder. The concrete deck was poured with concrete pumps and a Bidwell bridge paver."
Dubois' management team consists of Project Engineer II Daniel Gonzales and Project Engineer I Alex Carillo.
"Self-performing much of the work has allowed us to control the schedule and impacts on the public," Dubois said. "Since we started, there has been over 50,000 field man-hours on the project. This project has utilized all trades carpenters, operators, cement masons and laborers. Some of our key subcontractors are Malcolm Drilling, Integrity Rebar, Coreslab, Comet Electric."
Busy days have 40 C.A. Rasmussen and subcontractor employees on-site.
The amounts of excavated materials and new materials have not been finalized.
C.A. Rasmussen has a large fleet and having equipment in tip-top shape is essential for steady progress on its projects.
"C.A. Rasmussen owns and operates a large equipment fleet of over 300 pieces of iron," Dubois said. "The majority of the earthwork fleet is made up of John Deere and Caterpillar machines, with the asphalt paving equipment being Roadtec. The project will utilize excavators, loaders, dozers and the asphalt paving spread to complete the [work]."
C.A. Rasmussen is supported by Coastline Equipment for John Deere, Quinn for Caterpillar and Hermann Equipment for Roadtec.
"Our equipment division, led by Chris Quillen, is in close contact with all our dealers to ensure we minimize downtime," Dubois said.
Irwin Rapoport
A journalist who started his career at a weekly community newspaper, Irwin Rapoport has written about construction and architecture for more than 15 years, as well as a variety of other subjects, such as recycling, environmental issues, business supply chains, property development, pulp and paper, agriculture, solar power and energy, and education. Getting the story right and illustrating the hard work and professionalism that goes into completing road, bridge, and building projects is important to him. A key element of his construction articles is to provide readers with an opportunity to see how general contractors and departments of transportation complete their projects and address challenges so that lessons learned can be shared with a wider audience.
Rapoport has a BA in History and a Minor in Political Science from Concordia University. His hobbies include hiking, birding, cycling, reading, going to concerts and plays, hanging out with friends and family, and architecture. He is keen to one day write an MA thesis on military and economic planning by the Great Powers prior to the start of the First World War.
Read more from Irwin Rapoport here.
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