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Noticed this on my way to a meeting today: some roads around Tokyo are getting their surfaces redone with a kind of asphalt that traps rainwater.

What’s the point? Well as you know, asphalt is a rather heat-absorbing material, which means it is not a very good thing to have all around you during summer. So the Japanese have figured out a way of trapping rainwater inside the top 10cm or so of the asphalt surface on roads, without making the road too slippery. When that trapped rainwater evaporates, evaporative cooling naturally cools down the road surface.

Very neat.