AGOURA HILLS, Calif. — Following five weeks of overnight lane closures, construction crews have completed the installation of 82 massive girders that will eventually support a wildlife crossing over the Ventura (101) Freeway near Agoura Hills, officials said Tuesday.

All southbound lanes of the 101 Freeway will be closed between Cheseboro and Liberty Canyon roads between 11 p.m. Tuesday and 4 a.m. Wednesday, so crews can remove the large crane that was used to install the girders over each side of the freeway.

All northbound lanes will remain open. No additional overnight closures in the area are immediately planned now that the girder work has been completed.

Installation of the girders began on April 15, starting on the southbound side of the freeway and prompting daily overnight closures of those lanes. At the beginning of May, the work shifted to the northbound side, prompting nightly closures of those lanes.

Each of the girders used for the project weighs between 126 and 140 tons, stretching from the center median to the freeway shoulder.

Construction on the wildlife crossing began in 2022, and it is expected to be completed by late 2025 or early 2026.

The fully landscaped crossing is designed to provide a connection between the small population of mountain lions in the Santa Monica Mountains and the larger and genetically diverse populations to the north. The crossing will be the largest of its type in the nation, officials said.

Decades of road construction and development have been deadly for animals trying to cross the area's freeways, while creating islands of habitat that have genetically isolated wildlife ranging from bobcats to birds and lizards.

Wildlife advocates hope the crossing can save the threatened local population of mountain lions from extinction, which could become inevitable if lions continue a historic pattern of inbreeding due to the limited numbers of cats in the area.

More information about the project is available online.