Crabs' Migration Reveals Unexpected Insights for Modern Infrastructure Planning

In various parts of the world, roads have become more than just paths for vehicles. They are now spaces where humans and wildlife coexist, creating a unique blend of nature and civilization.

On the remote Colombian island of Providencia, every year, an annual mass migration of black crabs takes place. To ensure the safety of these migrating crabs, the military on Providencia has a "crab watch division" to prevent roadkill. Similarly, on Christmas Island, an Australian territory, tens of millions of red crabs migrate seaward in October and November. To help these crabs safely cross a busy road, the government installed its first "crab bridge" in 2012. The bridge has significantly reduced the number of crabs getting crushed along the road.

Roads, however, can have a significant ecological impact. They can prevent animal migration and mating, repel songbirds, and kill wildlife with tire particles. In the United States, roadkill claims more than a million vertebrate victims per day. To mitigate this, infrastructure that connects with the land rather than conquering it has emerged.

One such example is the highway in Brazil that winds through a state park near São Paulo. Every night, this highway closes to protect animals, and its design thwarts high speeds, forcing drivers to drive at a leisurely pace. The highway winds sinuously through the forest, crimped by frequent hairpin turns, and rises and falls like a gentle rollercoaster.

In contrast, the rebuilt highway in Montana includes 41 wildlife crossings: tunnels, underpasses, and a bridge. These crossings have allowed thousands of animals to safely navigate the road. Similarly, in Denali National Park, private vehicles are generally prohibited from most of the central park road, allowing wildlife to migrate safely during prolonged gaps in traffic.

The Denali National Park bus system unites its riders in the common pursuit of spotting wildlife, turning tourism from a solitary experience into a communal one. Some societies have also developed traditions to honor animals that are affected by roads.

However, roads can also pose a true existential threat to vanishingly rare species like Iran's Asiatic cheetah. Cars provide a primary way for humans to experience national parks and forests, but they can also disrupt the natural habitat and endanger wildlife.

The concept behind infrastructure that does not conquer the land but connects with it is to build roads or pathways that integrate harmoniously with the landscape and communities, fostering unity rather than division. Such a road in Brazil is the "Trans-Amazonian Highway," which was designed to connect remote regions without overwhelming or dominating them but promoting integration with the vast Amazon region.

As we continue to develop and expand our infrastructure, it is essential to consider the impact on wildlife and the environment. By building roads that coexist with nature, we can preserve the beauty of our world while still meeting the needs of a growing population.