For motorists, a freeway is a way to get from Point A to Point B (usually) quickly and safely. But for the wildlife whose habit is fragmented by roadways, a freeway is a barrier — a barrier that constrains migration, limits food supplies, and threatens biodiversity. Recognizing the challenges that freeways can create for animal populations, Caltrans continues to look for ways to mitigate impacts on wildlife, which you can read about here and here.
And here. The LA Times today has an interesting article about how US 101 (and the Pacific Ocean and agricultural fields) are constraining the mountain lion population in the Santa Monica mountains. Caltrans Senior Environmental Planner Barbara Marquez was interviewed for the story.
Currently, Caltrans is seeking funding for a study that would examine alternatives for constructing a wildlife crossing across US 101 at Liberty Canyon, which is part of an important wildlife corridor connecting the Santa Susana Mountains and the Santa Monica Mountains.
What sort of alternatives would the study look at? Possibly a tunnel, an overcrossing, fencing, or most likely, some combination of strategies. Here's an example of a culvert used as a wildlife crossing across SR-23, a strategy that has proven effective in reducing mortality rates at this location:
And here's some raccoons, also using an SR-23 culvert:
Caltrans cleans out the culverts regularly to ensure that animals can get through. Here's an example of a beautiful wildlife overcrossing in Canada's Banff National Park over the Trans-Canada Highway:
Once funding is secured for the Liberty Canyon study and an appropriate solution is selected and designed, the next major hurdle will be to get funding for construction.
For more information on wildlife crossings, check out “critter crossings” on the Federal Highway Administration site.