Japan is a mountainous country, and you have likely noticed that there are plenty of slopes wherever you go. In fact, districts like Shibuya and Kagurazaka in Tokyo are characteristically known for their many steep inclines. Have you ever noticed that these sloping roads often have circular indentations that look like doughnuts? These are a unique and quintessential feature of Japanese road engineering designed to keep both drivers and pedestrians safe.
What is O-gata Suberidome (O型滑り止め)?
Literally translated as “O-shaped anti-slip grooves,” these circular indentations are more than just a quirky design. Their primary purpose is to improve traction on steep slopes. The “doughnut” rings create high-friction edges that help tires grip the road. This is particularly vital in preventing cars from skidding when the surface becomes slick during Japan’s heavy rainy seasons or winter snowfalls. Japanese road regulations typically require an anti-slip surface on grades of 7% or steeper.
Does it actually work?
According to historical safety data from the Ministry of Land, Infrastructure, Transport and Tourism (MLIT), accident rates on steep inclines have declined by as much as 80% in areas where these grooves were introduced. As of 2025–2026, these patterns remain a standard safety feature across the country, from public mountain passes to steep private garage ramps.
Today, you see these grooves in parking lots as well as steep garages. If you’re wearing heels tread carefully!
For slopes that are not very steep, you often see colored asphalt. On your next trip to Japan, don’t forget to check out these measures that make roads safer!
A Simple but Effective Life-Saver
The “doughnut” roads are a perfect example of Japanese attention to detail in public safety. On your next trip, keep an eye out for these grooves—they are a silent guardian making Japan’s steep streets safer for everyone!
