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Throughout the Brazilian Amazon, more than 95% of deforestation occurs within a few miles of a road. If no roads were built through these areas, the ecosystems would be far more intact, and biodiversity would be more likely to thrive.

But roads have been built—and disconcertingly, a lot more are going to be built.

A pair of new reports from researchers at James Cook University in Australia drive home this message. “Roads to Riches or Ruin?”, published Thursday in the journal Science, explains how in just the next three years paved roads will double in length in Asia’s developing nations. In the next 30 years, the total new paved roads could approach 25 million kilometers (15.5 million miles) worldwide—enough to circle the planet more than 600 times. The overwhelming majority of these roads will be built in developing nations, where oversight is weak and environmental protections are often loose.

Dr. William Laurance of JCU, an author on both reports, told Earther that roads and other big infrastructure are “exploding like never before.”

“There are many worrying projects worldwide—more than you would believe,” he said. “But nothing tops China’s One Road One Belt program, which will create an octopus of roads, highways, railroads and other trade routes between China and some 70 other nations across Asia, Europe and Africa. It’s a true world-changer.”

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According to the new reports, Chinese investments in big infrastructure and extractive industries are also starting to surge in Latin America.

The authors are especially concerned about new roads in tropical and subtropical areas, where even well-built thruways can quickly fall into disrepair and become useless, slumping, pot-holed eyesores. They argue that we should avoid building many of these roads not only because of their environmental toll, but because of the costs.

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“Unless there’s expensive ongoing maintenance, big road projects can easily become giant money-losers for developing nations,” said JCU’s Mohammed Alamgir, lead author of the other report published in Current Biology, in a statement. “One can’t avoid the conclusion that many ambitious schemes for road expansion are veering dangerously off-track.”

According to that study, few roads built in areas with high rainfall have the culverts, bridges, or other drainage structures needed to properly divert water: “The recurring impediment of water causes localized flooding and vegetation mortality, peaking during periods of intense rainfall.”

Laurance said that in these regions, corruption is often a major reason projects that saddle the public with debt while providing little long-term benefit get built.

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Ultimately, Laurance hopes this research will help squeeze more economic and social benefits out of fewer, better-sited roads.

“Too often we think we can build roads anywhere and then just put ‘band-aids’ on the road to fix the landscape—for example, we create little tunnels under the road or overpasses above it, to allow birds and squirrels to disperse back and forth,” he said. “In fact such measures are rarely effective for rare and endangered species, and they’re often very expensive.”

The best solution for these critical areas might just be to stop building roads. That way you avoid the “first cut,” which, like a gateway drug, often leads to overuse, exploitation, and bigger issues down the road.

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“Once the first road happens, deforestation tends to spread in a cancer-like fashion along the road, which in turn spawns spider-webs of secondary and tertiary roads and also attract deforestation,” said Laurance. “The best solution is not to build the road at all in critical habitats—that’s comparable to not getting cancer in the first place.”