Wildlife crossing near Zakrzów, Poland © bbsferrari/Getty Images

Roads solved one problem but quietly created another. People could travel faster than ever, while wildlife faced highways cutting across routes they had followed for generations. The result was more collisions, fragmented habitats and isolated wildlife populations. That challenge led to wildlife crossings called ecoducts: bridges or tunnels designed to reconnect habitats and give animals a safe way across busy roads. Some of the earliest modern examples appeared in France during the 1950s, while the Netherlands later refined the concept with broad, green bridges covered in soil and native vegetation.