Zebra crossings—the striped crosswalks common on roads around the world—don't necessarily work very well. In one Swedish study, drivers stopped for pedestrians only 5% of the time at the crosswalks, and rarely slowed down.
A city in India is experimenting with another approach: By adding some perspective shading to the stripes, the crosswalk looks a little like a roadblock from a distance.
Artists Saumya Pandya Thakkar and Shakuntala Pandya were asked to paint the crosswalks by a local company that manages the highways in Ahmedabad, India. "They asked us to do something for accident-prone zones near schools," says Thakkar. "A lot of schoolkids were crossing the road, and it was not safe for them because of the high speed of the highway."
The artists had seen a similar optical illusion in photos from China, and decided to attempt it in Ahmedabad, painting four crosswalks in the city in January. Months later, it seems to be working. "They are very happy with it," Thakkar says. "Since then, they have marked that there is no accident there now."
Because of the way the human eye works, the illusion shows up only slightly at a distance—enough to make someone slow down—but appears two-dimensional up close, so drivers don't suddenly brake.
"It's better than normal artwork, but not as perfect as it looks in photographs," she says. "So it's not that dangerous for the drivers, because they can make out that this is just a painting. But the idea is that they pay attention because of the new creations."