Construction on “the world’s largest wildlife crossing” will close a portion of the Los Angeles County’s 101 Freeway overnight on weekdays for several weeks starting Monday.

The crossing will span 10 lanes of highway and aim to provide safe passage for wildlife – especially mountain lions – from the Santa Monica Mountains into the Simi Hills of the Santa Susana mountain range.

The California Department of Transportation (Caltrans) began constructing the crossing in April 2022, CNN previously reported. As the project nears completion in 2025, the bridge will be covered in soil and native plants to blend in with the natural surroundings.

Officials say major highways are barriers to wildlife, affecting animals’ movement and gene pools.

Caltrans says the crossing will be the largest of its type in the US, while the project’s official website says it will be the largest in the world and “will serve as a global model for urban wildlife conservation.”

Starting Monday, all southbound lanes of the highway in the Agoura Hills area will be closed from Cheseboro Road to Liberty Canyon Road for about five hours beginning at 11:59 p.m. PT on weekdays, according to Caltrans.

Closures will shift to northbound lanes as work on the crossing progresses, the department said.

“These closures are for the safety of the public while crews place girders over the freeway to construct the Wallis Annenberg Wildlife Crossing, a vegetated bridge across Highway 101 to reconnect wildlife habitat,” Caltrans said.

The schedule is subject to change because of weather conditions or operational reasons, and detours on local streets will be provided.

More than 5,000 individual contributions were made for building the crossing, Caltrans said when the project began. It is named for the president and CEO of the Annenberg Foundation, a family foundation that supports non-profits.

“We can coexist side by side with all kinds of wild instead of paving it over and choking it off,” said Wallis Annenberg at the groundbreaking ceremony. “It is about bringing more attention to an ingenious solution so urban wildlife and ecosystems like this one cannot only survive, but thrive.”

The crossing will provide habitat access to coyotes, bobcats, deer, snakes, lizards, toads and even ants, but cougars will be among its chief beneficiaries, the National Parks Service has said.

Mountain lions typically have a territory of 150-200 miles but in Los Angeles, they have been restricted to a freeway-ringed “urban island,” causing inbreeding, according to the NPS.

“Genetic analyses indicate that lions in the Santa Monica Mountains have among the lowest genetic diversity of any mountain lion population ever documented,” the NPS said.

The project’s website notes the crossing will “provide the connectivity needed to fix this genetic collapse by allowing for the cats living north of the Santa Monica Mountains to travel into the range and for animals living south of the freeway to disperse out of the area.”

Famed mountain lion P-22 was born in the Santa Monica Mountains and had crossed two busy Southern California highways, only to become isolated and roam Los Angeles’ sprawling Griffith Park.

The beloved cougar was euthanized in late 2022 after suffering severe injuries consistent with being struck by a vehicle and chronic conditions that impaired his ability to function in the wild, according to the California Department of Fish and Wildlife.