Roads to riches or ruin? Global infrastructure expansion must balance social benefits and environmental hazards

[Extract] We are living in the most explosive era of infrastructure expansion in human history (1, 2). In the next 3 years, paved roads are projected to double in length in Asia’s developing nations (3); in the next three decades, the total length of additional paved roads could approach 25 million kilometers worldwide—enough to encircle the planet more than 600 times (1). Nine-tenths of all new infrastructure is being built in developing nations (1), mainly in tropical and subtropical regions that contain Earth’s most diverse ecosystems. In a world that is projected to have 2 billion vehicles by 2030 (4), we need a better understanding of the impacts of roads and other infrastructure on our planet, societies, and economies (1–3, 5)—and more effective planning to ensure that the benefits of infrastructure outstrip its costs