101 Freeway to experience overnight closures for construction on wildlife crossing in Agoura Hills

The 101 Freeway will experience a series of overnight closures due to construction on the Wallis Annenberg Wildlife Crossing in Agoura Hills. 

As construction enters its next phase, crews will begin installing the massive concrete beams over the entire freeway starting on Monday evening at around 11:59 p.m. near the Liberty Canyon Road ramps. 

The first closure will impact southbound lanes between Cheseboro Road and Liberty Canyon Road until 5 a.m. on Tuesday. The overnight closures will repeat every night through Friday. 

The closures are necessary as crews lift and install the large concrete beams, also called girders, over the freeway. Each is said to weigh between 126 and 140 tons and will stretch from the center median to the freeway shoulder, according to the California Department of Transportation. 

As soon as the girders are installed on the southbound side of the freeway, the work will shift to northbound lanes. 

Overall, the girder operation could span between six and eight weeks, according to Caltrans. In all, they expect that 82 total girders will be installed. 

"We are very excited to celebrate this big milestone in the construction of the Wallis Annenberg Wildlife Crossing," said a statement from Beth Pratt, the California Regional Executive Director for the National Wildlife Federation. "With the placement of the horizontal supports, the structure is truly going to start looking like the bridge it will become. We know that closures of the freeway do have impacts on traffic and the community, and we apologize for any inconvenience this may cause."

As a result of the closures, Caltrans has created a series of detours for drivers. Those who need to head through the area are urged to consider using the 118 Freeway as an alternate between SR-23 and the 405 Freeway. 

"Caltrans has a thorough plan for detours, and we trust their excellent team to manage this to minimize disruption," Pratt's sttement said. "These 'Closures for Cougars' are for a good cause — helping to save the area mountain lions from extinction and ensuring a future for all wildlife in the Santa Monica Mountains."

The wildlife crossing's construction began in 2022 and is expected to be completed no later than early 2026. 

Once finished, it will span over the entirety of the freeway, allowing a connection between the small population of mountain lions located in the Santa Monica Mountains and the more diverse populations in the north. 

Advocates are hopeful that the crossing will save the lives of not only the threatened local mountain lions, but dozens of other animals native to the area including rabbits, coyote and deer.