Over the weekend, winter storm Jonas dumped epic amounts of snow on the East Coast. Parts of New York City found themselves under 30 inches of snow. Washington, DC got hit with 18 inches, Philly with 22, and Baltimore with a record-setting 29, according to the Weather Channel.

All that snow's done a fair bit of damage to the region's transportation networks, closing down subways, slowing car traffic, and canceling more than 13,000 flights. But this kind of blizzard also delivers an unexpected bonus for everyone who advocates urban design that values pedestrians over cars. The natural path of snowplows in the storm's aftermath has created a network of what some call "sneckdowns"—a somewhat natural version of an urban design feature that proponents say can make city streets safer and more pleasant.

"Sneckdown" is a combination of "snow" and "neckdown," also known as a curb extension (if you think "sneckdown" is silly, try "snurb extension"). A curb extension is a traffic calming device that extends the sidewalk further into the street, taking space away from cars and giving it back to those on foot. The idea isn't to remove a lane of traffic, but to tighten the corner radius of the intersection. It's the opposite of cutting corners.

To navigate a curb extension, drivers have to make turns that are closer to right angles, which means they have to slow down (the snow on the ground encourages slower speeds, too). "Minimizing turning speeds is crucial to pedestrian safety," says the National Association of City Transportation Officials' urban street design guide, since "corners are where drivers are most likely to encounter pedestrians crossing in the crosswalk."

So why not do this in all our cities where we don't want pedestrians to get mowed down? There's a growing effort to make American cities more sensitive to pedestrian safety. New York, San Francisco, LA, Portland, Washington, DC, Boston, and other major cities have pledged to drastically reduce pedestrian deaths, and curb extensions are a proven tool for doing that. But even for cities that want to make that shift, changing the infrastructure of their streets isn't so easy.

Even simple changes can be costly, and must move through lengthy, complicated approval and regulatory processes. Try to do that on a large scale, and things get expensive. That's why the National Association of City Transportation Officials recommends "interim design strategies"—using things like bollards and planters to temporarily and inexpensively change the shape of a street. That gives city planners and residents the chance to observe the effects of a curb extension without committing to a permanent change.

There's an even easier way to do that, without setting up plastic bollards that'll probably get crushed anyway: Let it snow. Then bring out the plows.

Because plows are tasked with making streets drivable as quickly as possible, and because the snow they move has to go somewhere, they push snow out of driving lanes up against the curb—incidentally creating sneckdowns all over the place. All of a sudden, cars have just enough room to maneuver—not dominion over the entire street—giving amateur and professional urban planners the chance to rethink how streets are set up:

Curb extensions "have been very effective in making the driver slow down at corners," says Mitchell Moss, director of the Rudin Center for Transportation at New York University. He notes, however, that making the things with snow isn't such a perfect idea: If the weather stays cold, partially melted snow becomes ice, and pedestrians end up forced to traverse small mountains to get around. And Moss cautions against doing everything possible to slow traffic. "We live in an Amazon economy," he says. Trucks have to navigate our urban centers, and they must be accommodated.

Still, if you're snowed in on the East Coast and also care about making your city safer for those on foot, it's nice to have a silver lining. Even if it is more of a sooty gray.