US-101 Liberty Canyon Wildlife Crossing
A FIRST FOR CALIFORNIA
Caltrans proposes to build a wildlife crossing across U.S. Route 101 (US-101) just west of Liberty Canyon Road in the City of Agoura Hills in Los Angeles County. The purpose is to help maintain wildlife populations that travel between the Santa Monica Mountains and Simi Hills, and ultimately to the Sierra Madre Mountain Range. This linkage has been identified in numerous county, city and regional plans and publications as a critically important connection for wildlife. Such wildlife crossings have been built and used successfully in other states and countries. The Liberty Canyon Wildlife Crossing would be the first of its kind in California.
The purpose of the proposed project is to provide a safe and sustainable wildlife passage across the freeway in order to help create an important linkage in the region. The crossing would help reduce wildlife mortality, ease animal movement across habitats, and allow for the exchange of genetic material. In particular, large mammals such as mountain lions and bobcats need large connected habitats in order to hunt, breed, and thrive. US-101 divides this previously contiguous ecosystem into isolated habitat fragments; for mountain lions, this has resulted in inbreeding, territorial fighting, and a decrease in genetic diversity. Without the addition of a wildlife crossing, the ecological and environmental impacts on wildlife movement that resulted from the original construction of US-101 will persist. The proposed project would also help mitigate anticipated future effects of climate change on the current distributions of species across habitats.
|Alternative 3 (for reference only, design currently under review) - rendering courtesy of Clark Stevens, Resource Conservation District f the Santa Monica Mountains|
The proposed project currently has 3 alternatives:
No Build – Alternative 1
The No Build Alternative would maintain the existing freeway configuration and would result in the continued restriction of wildlife movement into and out of the Santa Monica Mountains.
Build - Alternative 2
A 165-foot wide x 200-foot long bridge constructed across US-101 immediately west of Liberty Canyon Road at mile marker 33.0. The bridge would be vegetated to resemble natural wildlife habitat, and include a hiking trail. Features such as soundwalls and vegetation on the overcrossing would mitigate traffic noise, block light, and aesthetically blend the crossing with the surrounding natural landscape.
Build – Alternative 3
Same as Alternative 2 with an extension of the vegetated bridge over Agoura Road south of US-101. The slope between the end of the bridge and Agoura Road would be built up to grade before descending to join the existing ground. Associated retaining wall systems would also be constructed. The expectation is that the crossing extension would help alleviate wildlife impacts and mortality on Agoura Road.
Two other alternatives exist for this project, but were not fully developed due to recommendations from Caltrans’ Project Delivery Team. Both alternatives proposed to construct a tunnel under US-101 to serve as a wildlife crossing. Neither tunnel would convey wildlife across and to the south of Agoura Road since they would have entrances to the north of Agoura Road, adjacent to US-101.
The first, smaller, tunnel was a 13’ x 13’ jacked box culvert located west of Liberty Canyon Road. This tunnel would not accommodate the same wide range of wildlife species as an overcrossing. A tunnel study, originally done by the Federal Highway Administration Central Federal Lands Highway Division (FHWA-CFLHD) in 2010 and updated in 2015, estimated the cost at approximately $19.7 million (see the Project Study Report, Attachment I). It was agreed that the cost-benefit would not achieve the goals of the project.
The second, larger, tunnel was a 32’ wide x 15’ high cast-in-place rectangular culvert located west of Liberty Canyon Road. This tunnel was not considered feasible due to constructability considerations and high traffic impacts. Specifically, such a large tunnel would require using the cut-and-cover technique and the closure of US-101, one of the busiest freeways in the region. In addition, it was estimated that such a large tunnel would be more costly than an overcrossing.
Who is Involved
This project presents a unique opportunity for public-private partnership. Current partners in the project include Caltrans, the Mountains Recreation and Conservation Authority, the Santa Monica Mountains Conservancy, the National Park Service, and the Resource Conservation District of the Santa Monica Mountains. Additional support and partnership is being provided by Senator Fran Pavley, Assemblymember Richard Bloom, LA County Supervisor Sheila Kuehl, the National Wildlife Federation, Congressman Ted Lieu, Ventura County Supervisor Linda Parks, the City of Agoura Hills, the City of Thousand Oaks, and the State Coastal Conservancy.
Where We’re At In The Process
The project is currently in development and is in the Project Approval & Environmental Document (PA/ED) phase.
A joint Initial Study/Environmental Assessment (IS/EA) is being prepared as per to the California Environmental Quality Act and the National Environmental Policy Act.
January 14, 2016 - Public Scoping Meeting
The public comment period will be open from December 14, 2015 to January 29, 2016.
California Department of Transportation
- Location Map
- Drawings of Alternatives
- Alternative 1 (No build) - Current view looking northeast
- Alternative 2 – Build crossing over US-101 (for reference only, design currently under review)
- Alternative 3 -Preliminary design profile (for reference only, design currently under review)
- Alternative 3 – Build with extension over Agoura Road (for reference only, design currently under review)
- Proposed crossing location (preliminary draft)
- http://www.cbsnews.com/news/60-minutes-mountain-lions-of-los-angeles-2/ http://www.topangamessenger.com/story_detail.php?ArticleID=8071
District 7 Links
Phone: (213) 897-3656