Passageway 1 Overpass | I-15WildlifeCrossing

Overpass Design

Why Choose A Overpass

Our Overpass design creates a bridge over the I-15 freeway that connects two currently isolated habitats. The goal of this design is to increase wildlife connectivity, especially between two Mountain Lion habitats, and in turn lower the risk of inbreeding and vehicle collisions that these populations currently face. This design is ideal because it blends with the surrounding landscape to create an easily accessible and attractive crossing for wildlife to use. The Overpass design also has an important impact on public awareness of wildlife and connectivity issues since it will be seen by the public more than a Culvert or Underpass would. Our design makes the most of this fact by covering the Overpass in artwork that depicts its usage and peaks the public's interest. The Overpass design is also preferred over other methods because a wide range of different wildlife species have been seen to use Overpasses more than Underpasses (according to 17-year-long study on Banff National Park’s wildlife infrastructure).

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Satellite Location

Yellow dots is an indication of California Mountain Lion movement. Data found during Winston Vickers', of US Davis, research into the California Mountain Lion in the Temecula area. The highlighted interstate is part of I-15 Wildlife Crossing, project location. Two Sites were found to be suitable for an Overpass, linked below are the tables that were used to determine the ideal site.

Site Selection Criteria

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Our Design

Alternative 1

Traditional- Wildlife Crossing Design

Alternative 2

Innovative-

Hypar-Nature Wildlife

Crossing Design

Vegetation Design

In keeping with the natural landscape of Temecula, CA, our vegetation design focuses on coastal sage scrub plants. These plants were picked due to their commonality in the area, ground cover ability, root structure that is appropriate for a Wildlife Overpass, durability in drought conditions, and lastly their desirability to the native animals. Coastal sage scrub plants selected: California Sagebrush, Black Sage, California Buckwheat, Sugar Bush, Brittlebush, California Poppy, White Sage, and Purple Needle Grass. Bahia Grass, native to Southern California, will be used as an additional ground cover. The Vegetation design includes berm walls on both sides of the Overpass to help mitigate traffic noise and act as a barrier. Geofoam will insulate the centers of the berm wall to reduce overall weight and amount of soil used.

Research For Design

The design of Passageway 3 is a Wildlife Overpass structure that provides a safe, natural corridor for Mountain Lions to cross. Throughout our project, the Overpass Design Team has established two possible overpass site locations. The coordinates for Site #1 are 33°27'4.10"N 117° 8'7.26"W and Site #2's coordinates are 33°27'16.33"N 117° 8'8.04"W. We chose these locations based on a carefully selected and researched set of criteria. Some of the criteria used were conserved land on both sides of the freeway, wildlife accessibility, light pollution, constructability, and human activity. The overpass design features two possible design alternatives. The first alternative is a traditional wildlife overpass that was developed with the use of design element considerations. These elements consisted of recommendations for Wildlife Overpasses, Caltrans standards, and also a structural analysis to test for feasibility. The second design alternative is a prototype design referred to as the "Hypar-Nature Design." The elements used in these design considerations were cost, installation, the ability for alterations, innovation, animal capacity, and visual effects. These design alternatives were being considered at both sites. The locations we chose can support either of the design alternatives. As a team we determined that site 2 with either alternative is best and will benefit the Mountain Lions most significantly. The information we have on this website has been developed by our research and feedback from experts ranging from engineers to wildlife specialists.