Wildlife Overpasses: A Testament to Human Ingenuity and Environmental Stewardship

As roads and highways expand, they often cut through natural habitats, disrupting animals’ natural movements, potentially trapping them in one area and putting them at risk. Wildlife overpasses have emerged as a practical solution, demonstrating how design minimizes harm and conflict between humans and the environment. 

What Is a Wildlife Overpass?

A wildlife overpass is a bridge-like structure that allows animals to cross over, and move through, different areas. These spaces are exclusive to wildlife — humans or vehicles don’t have access to these spaces. Cities usually build wildlife bridges over highways, roads and other spaces known to be dangerous to animals.

An overpass is one type of wildlife crossing bridge, but it can also come in different forms to accommodate other creatures. Depending on the area, you can find animal tunnels, culverts and viaducts in highway planning and road improvement plans.

These structures can look different from one another — the design will depend on the ecosystem and what creatures will likely pass through. For example, wide animal bridges might be necessary for larger mammals like mountain lions or moose, while small culverts would be enough to support local amphibians or reptiles.

While crossings are artificial structures, designing them with organic material is usually helpful to make them look more natural and inviting to these creatures. Many wildlife bridges have carpets of grass, moss, branches and rocks to make them look seamless with the surrounding ecosystem.

How Crossings and Ecological Corridors Help Wildlife

Effective animal bridges take research, resources and effort to create. However, they are often worth it primarily due to their ability to save lives and preserve the natural environment. Protecting biodiversity is crucial, as species die-offs can disrupt entire ecosystems.

Here’s how crossings help wildlife survive in the modern world:

Avoiding Vehicle Collisions

One of the biggest benefits of wildlife crossings is their ability to protect different species from road accidents. Millions of animals die, or get injured, each year from vehicle-related accidents. From 2023 to 2024, Americans filed around 1.8 million auto insurance claims involving animal collisions.

When roads cut through animals’ natural habitat, the animals might not be aware of the dangers of these new structures, causing them to walk into harm’s way. Highways are particularly dangerous, as vehicles move fast, and wildlife and humans might not have enough time to react appropriately.

An animal overpass or underpass solves this problem by providing appropriate space for these creatures. These structures provide a safe passage, keeping both animals and humans safe from accidents.

Reaching Food and Water

Animals sometimes need to move around in search of food and water, which can often change with the seasons. For example, wolves can travel as far as 30 miles each day to hunt and feed their pack. Swedish elk usually trek miles and swim across rivers to reach greener pastures where they can graze for the rest of the year. 

An animal bridge over a highway or an underground wildlife tunnel ensures they can still use their migration routes and have access to enough food and water to survive in their environment.

Finding Mates

Different species travel for various reasons, one of which is procreation. In 2021, researchers found a deer traveling over 200 miles in three weeks. While this case was an outlier, juvenile males often travel long distances to seek mates. 

For many species, traveling is necessary to find a mate that helps create better genetic diversity. Wildlife crossings allow species to find suitable mates and avoid inbreeding, which can cause higher mortality rates and more frequent hereditary abnormalities.

Animals unable to find suitable mates can’t reproduce. Populations could dwindle if this situation continues for an extended period, leading to species endangerment and even extinction.

Avoiding Conflict With Humans

Wildlife crossings help provide enough space and resources for animals to move around and live without running into people. Wild creatures can sometimes reach human-populated areas due to a lack of resources or habitat loss. 

Ecological corridors and crossings prevent humans and wildlife from unnecessary interactions and possible conflict.

Adapting to Environmental Changes

Climate change affects animal habitats — rising temperatures and changing weather patterns could cause certain areas to no longer become habitable. For example, trees require water to survive — over 50% of a tree consists of water. If an area experiences drought, animals relying on trees for food and shelter might seek another place capable of supporting them. The same is true for other plants and vegetation.

Freedom of movement is required for species to survive these changes and find suitable alternatives. While ecological conservation and fighting climate change are necessary, providing safe passageways keeps species safe in the meantime.

3 Wildlife Crossings Helping Animals Live

Animal bridges are slowly, but surely, being built all over the world. There are currently around 1,500 wildlife crossings across 43 states in the U.S., and more are under construction. These developments contribute to a promising outlook for wildlife conservation and environmental protection. Look for these structures when you drive around the country:

1. Under Construction: Wallis Annenberg Crossing, California

The Wallis Annenberg Crossing is the biggest wildlife crossing project in the country — it is 174 feet wide and 210 feet long, stretching over 10-12 lanes of U.S. Highway 101, one of the longest roadways in the U.S. 

The project has been in talks since 1990, broke ground in 2022, and is now standing and being filled with soil for native plants in 2025. Native plants make sense for these projects, as they are more likely to attract wildlife and restore natural environments. The crossing is taking shape, involving scientists and consultants who aim to make the bridge seamless with the natural landscape.

2. Highway 9 Wildlife Crossing Project, Colorado

There are currently over 40 crossings in Colorado, built through the leadership of the Colorado Department of Transportation (CDOT) in partnership with other government agencies.

The Highway 9 Wildlife Crossing Project is one of its largest, including two overpasses and five underpasses. Since its completion, the state has seen a 90% decrease in wildlife-vehicle collisions.

3. I-80 Wildlife Bridge, Utah

While smaller than some of the other wildlife overpasses, the I-80 Wildlife Bridge in Utah is another successful example of an animal crossing. Built in 2018, the structure has helped prevent vehicular collisions with creatures in the area. 

The state’s crossings currently enjoy an 80% success rate, meaning this percentage of animals that approach the overpass proceed to cross it. The state has also recently won a $5.5 million grant to build three more overpasses.

A Path Forward

Wildlife overpasses are a powerful example of how engineering and environmental responsibility can intersect. They allow humans to connect different habitats, improve safety and coexist peacefully with local wildlife, building a world where nature and progress can move forward together.