The essential insight of road ecology is this: Roads warp the earth in every way and at every scale, from the polluted soils that line their shoulders to the skies they besmog. They taint rivers, invite poachers, tweak genes. They manipulate life’s fundamental processes: pollination, scavenging, sex, death.
Among all the road’s ecological disasters, though, the most vexing may be noise pollution — the hiss of tires, the grumble of engines, the gasp of air brakes, the blare of horns. Noise bleeds into its surroundings, a toxic plume that drifts from its source like sewage. Unlike roadkill, it billows beyond pavement; unlike the severance of deer migrations, it has no obvious remedy. More than 80% of the United States lies within a kilometer (approximately 0.6 of a mile) of a road, a distance at which cars project 20 decibels and trucks and motorcycles around 40, the equivalent of a humming fridge.
Like most road impacts, noise is an ancient problem. The incessant rumble of Rome’s wagons, griped the poet Juvenal 2,000 years ago, was “sufficient to wake the dead.” To walk in 19th-century New York, Walt Whitman wrote in Song of Myself, was to experience the “blab of the pave,” including the “tires of carts” and “the clank of the shod horses.” As car traffic swelled in the 20th century, road noise became a public-health crisis, interrupting sleep, impairing cognition and triggering the release of stress hormones that lead to high blood pressure, diabetes, heart attacks and strokes. A 2019 report by one French advocacy group calculated that noise pollution shortens the average Parisian life span by 10 months. In the loudest neighborhoods, it truncates lives by more than three years.
To a road ecologist, noise is pernicious precisely because it isn’t confined to cities. Road noise also afflicts national parks and other ostensibly protected areas, many of which have been gutted by roads to accommodate tourists. A vehicle inching along Going-to-the-Sun Road, the byway that wends through Glacier National Park, casts a sonic shadow nearly three miles wide. “Once you notice noise, you can’t ignore it,” conservation biologist Rachel Buxton told me. “You’re out in the wilderness to have this particular type of experience where you escape and relax, and noise ruins it. It totally ruins it.”
And road noise isn’t merely an irritant; it’s also a form of habitat loss. In Glacier, the distant grind of gears startles mountain goats; in one Iranian, it annually hosts a group of travelers even more disruptive than aliens: bikers from the nearby Sturgis Motorcycle Rally. The roaring fleet of Harleys and Yamahas, Buxton has found, pushes prairie dogs back into their burrows, drives off deer, and deters bats from feeding near the monument for weeks. Had Spielberg’s extraterrestrials arrived mid- Sturgis, Richard Dreyfuss would have missed their five-note musical greeting.
