Freeway bridges could aid wildlife
In what could be a first for Southern California, bridges may be built over a new Riverside County freeway for neither cars nor pedestrians, but wildlife.
In unveiling a preferred route recently for the $3.1 billion Mid County Parkway, a 32-mile east-west freeway that may be built next decade, officials said project features include two exclusive bridges for coyotes, bobcats and Stephens kangaroo rats.
Far from your typical bridge, the spans each would have a several-feet-deep base of dirt supporting native shrubs and grasses, John Standiford, a spokesman for the Riverside County Transportation Commission, said Wednesday. The commission is coordinating efforts to expand existing highways and build new ones in a bid to keep pace with Riverside County's rapid growth.
"The idea is to try to make them look like the natural environment so that the creatures will actually use them," Standiford said.
Construction on the freeway is expected to begin in 2011.
One of the bridges would be built south of Lake Mathews, between Temescal Canyon Road and Lake Mathews Drive; the other would be built farther east between Gavilan and Old Elsinore roads.
Emerging from a regional planning effort several years ago, Mid County Parkway is intended to relieve pressure on congested Highway 91, the major artery linking Riverside and Orange counties. Mid County Parkway also could become a second conduit for commuter traffic headed for Orange County, as it lines up with a potential route for a new highway tunnel under the Cleveland National Forest north of Lake Elsinore.
The wildlife bridges could be a first for Southern California's state highway system. Several wildlife experts said they were unaware of any existing such bridge in the region. And California Department of Transportation officials said currently there are no such bridges over highways in Riverside, San Diego and San Bernardino counties.
Meanwhile, Riverside County officials are proposing a similar, although slightly different artificial wildlife crossing at a county road in French Valley east of Murrieta.
Juan Perez, deputy director of transportation, said the county next spring will begin working to extend Clinton Keith Road east toward Winchester Road. In doing so, Perez said, the county will put the road in a culvert near the midpoint between Winchester and Interstate 215. He said the county will plant a vegetated crossing on top the structure, to provide a travel corridor for animals -- including the imperiled Quino checkerspot butterfly. A federal requirement to ease the road's impact on prime butterfly habitat is the driving force behind the crossing project.
At the same time, San Diego State University scientists are studying whether a wildlife bridge over eight-lane Interstate 15 would help mountain lions cross back and forth between Palomar Mountain and the mountains west of Temecula.
Matt Rahn, director of the university's field station programs, including nearby Santa Margarita Ecological Reserve, said scientists hope to unveil a plan for a bridge somewhere north of the Riverside-San Diego county line in two years.
Environmentalists, biologists and federal wildlife officials said Wednesday they generally support the transportation commission's proposal for two animal bridges over Mid County Parkway, which will cross western Riverside County's environmentally sensitive Lake Mathews area.
"This is a big step forward," said Paul Beier, a wildlife ecology professor at Northern Arizona University and an expert on Southern California's mountain lions, in a telephone interview. "And there is strong evidence where they have been studied -- mostly in Banff National Park -- that they do work very well."
Grizzly bears, wolves and elk have grown accustomed to using a pair of wildlife bridges in the Canadian national park, according to the park's Web site. Other bridges have been built or are proposed in states such as Washington and Colorado.
Beier said typically very few animals travel across such bridges at first, but after about two years they tend to catch on and use overpasses regularly.
The concept is hardly a perfect one, though, said Dan Silver, executive director for the Endangered Habitats League, an environmental group based in Los Angeles.
"It sounds like it might work for some species, not for others," Silver said, saying bridges are useful mostly for large animals. "At best, it's a partial mitigation measure."
It would seem that many animals wouldn't figure out the overpasses were meant for them, Silver said.
"It's not as though they can read signs," he said.
Still, Silver said building bridges is better than doing nothing, to help make up for the mammoth artificial obstacle of a six- to eight-lane highway teeming with cars moving along at an 80 mph clip.
"A lot of species are going to get killed trying to cross the road," he said.
Charles Landry, a project consultant for the transportation commission, said the overpasses would be about 220 feet long and at least 75 feet wide.
In several places, tunnels are planned. Tunnels are used widely to help animals move back and forth under state highways. But Landry said in a couple locations Mid County Parkway will be lower than the surrounding terrain, and that prompted officials to propose bridges.
The new multilane artery will connect Interstates 15 and 215 and Highway 79 along a corridor stretching from south Corona to Hemet. The freeway will have 14 interchanges.