One of the most immediate impacts of a world without surface roads would be a huge freeing up of space across the globe.
In rural areas, this could mean more land for farming or for reseeding, to help boost wildlife. draw carbon from the air. It would also alleviate one of the huge problems with roads: they fragment landscapes.
For animals, roads can act as a barrier, separating species from each other or from their prey. Global expansion of road networks threatens all top predator conservation efforts, says a recent article, including reducing their genetic connectivity and increasing poaching, with sloth bears and tigers being most at risk. Increased fragmentation also leads to more carbon emissions because it increases the amount of forest edges, where there are higher tree mortality.
Roads can also interrupt the flow of water, says Alisa Coffin, research ecologist at the US Department of Agriculture. It points to the Tamiami Trail, a road connecting Tampa and Miami that has had disastrous effects for the Everglades by blocking the flow of water, leading to an increase in forest fires and affecting plants and animals. “It’s an example of how a road was built without really understanding what the impacts would be,” Coffin said.
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Collisions between animals and cars are another big problem. Sarah Perkins, Lecturer at Cardiff University, coordinates Project splashes, a decade-old citizen science research project that monitors wildlife killed on Britain’s roads. He receives around 10,000 reports of dead animals each year, she said, but Perkins believes that’s a fraction of the actual total. Some studies put the number of road deaths at hundreds of millions a year in Europe alone.
Putting the roads underground “could reduce collisions between wildlife and vehicles”, says Perkins – provided the animals do not use the tunnels. It would also eliminate light and noise pollution, which can affect animal behavior around roads, she adds.
Despite these huge ecological impacts of removing roads, it would be in cities, which are expected to be home to 70% of the world’s population by 2050, that the newly freed space would have the greatest impact on people.
“Can you imagine how cities will be transformed? asks Tom Ireland, director of tunnel projects at engineering firm Aurecon. “If you want to revitalize downtown, you walk the roads.” It would open up space for trees, linear parks, landscaping, sidewalk cafes and dozens of other public amenities.