The Issaquah Alps Trails Club is advocating for the inclusion of safe wildlife passages in the design for the expansion of SR-18, but why are these passages so important?

The beautiful landscape we call home is also an important habitat for many wildlife species. Large roads, like SR-18 or I-90, that run through them fragment this habitat and create danger for the animals that do try to cross them.

WSDOT reports that they receive 1,500 reports of vehicle collisions with wildlife each year. Out of those 1,500 collisions there are an average of 167 human injuries and one fatality. These numbers however, are likely low based on the number of roadkill removed from the highway each year. Most commonly, smaller species of animals are killed in these collisions such as raccoons, coyotes, opossums, and salamanders. Collisions with deer, elk, and larger mammals tend to be reported more frequently due to the property damage and human injury that is frequently involved.

Collisions are not only dangerous for animals and people, they can be expensive. The National Highway Traffic Safety Administration reports that deer-car collisions cost an average of $8,190 to repair and elk-vehicle collisions cost about $25,319.

Fortunately, it turns out that if given an alternative to crossing the road, many animals will take it.

If you’ve driven over Snoqualmie Pass recently, you will have seen a stunning example of what safe wildlife crossings can look like. Back in 2004, a coalition of organizations led by Conservation Northwest came together to advocate for the inclusion of high-quality wildlife passages in the I-90 expansion project. This advocacy resulted in the installation of four wildlife under-crossings and two wildlife bridges over the highway which have since been frequently used by wildlife of all kinds.

Many passages are much simpler in design than the bridges and are still effective. Wildlife passages can include underpasses, overpasses, amphibian tunnels, large culverts, and tunnels. The type of crossing needed depends significantly on the landscape and the animals involved- some prefer large open crossings areas, and others prefer smaller tunnels. This highlights the need for high-quality design and planning in these projects; no one wants to build a wildlife crossing that won’t work.

When it comes to SR-18, four areas have been identified as key for creating safe wildlife passages; Raging River, Deep Creek, Tiger Summit South, and Holder Creek all represent areas where habitat connectivity could be significantly improved with the inclusion of passages.