Joshin-estu Expressway's Pink High Friction Roads!

On a recent road trip to Hokuriku, I noticed a very distinct change in the roads once we reached the Myoko area. We entered a tunnel on "normal" asphalt, and when we exited it was instantly noticeable that the roads had a different texture and a slight pink hue.

Given that this is "Road Interaction Month" and because I was curious enough, I looked up what this texture and coloration is all about. As I suspected, it’s a road‑safety feature. There are several reasons for the difference, grounded in the terrain and weather conditions. For example, the Joshin-etsu Expressway cuts directly through the mountainous areas of Gunma, Nagano and Niigata. The reddish-pink asphalt helps alert drivers to slow down and prepare for changing road conditions. 

This expressway is also notorious for heavy winter snow, dense mountain fog, and black ice. The graveled texture and colored pavement create a sharp visual contrast against the elements, making lane boundaries easier to see. In addition, these surfaces often include anti‑skid treatments or resin coatings that improve traction during freeze–thaw cycles. They’re also more durable, standing up to snowplows, de‑icing agents, and constant winter moisture.

We passed through the area in a flash on the way to Hokuriku, yet it left me unexpectedly impressed and curious. Luckily, we were able to stop there on the way back. I love that even a simple road trip can turn into a subtle education in Japan.