Sydney, Oct 29 (IANS): The global explosion of new roads is rife with economic, social, and environmental dangers, Australian scientists have warned.

"We've scrutinized major roads and infrastructure projects around the world," said lead researcher William Laurance, professor at the James Cook University, Queensland.

"It's remarkable how many have serious hidden costs and risks."

The most urgent priority is limiting millions of kilometres of new roads being planned or built in high-rainfall areas, mostly in developing nations of the Asia-Pacific, Africa, and Latin America, said the study published in the journal Science.

"This is where ambition for quick profits meets nearly impossible engineering," Laurance said.

"Rainfall-drenched roads develop pot-holes, giant cracks and landslides so fast it's nearly unbelievable.

"They can quickly turn into giant money-losers," Laurance added.

By the year 2050, it is projected that there will be an additional 25 million kilometres of new paved roads on Earth.

And in just the next three years, paved roads are expected to double in length in Asia's developing nations.

"Many roads that are planned for wet, swampy or mountainous regions shouldn't be built, and that's based only on economic criteria," said Laurance.

"If you add in environmental and social costs, then the pendulum swings even harder against new roads, especially in forested areas with high environmental values," said study co-author Irene Burgues Arrea, an economist with the Alliance of Leading Environmental Researchers and Thinkers (ALERT) in Costa Rica.

"The public often ends up with major debts from failed roads. A few road developers and politicians get rich, but vital development opportunities are easily squandered," Laurance said.