When I walk or run or ride a bike, one of my main concerns is potholes. A little pothole is an inconvenience, but a big pothole is a problem, being a potential cause for a number of calamities. At night, big potholes are also a safety issue, for what I assume are obvious reasons.
The rain offers a solution - a pothole filled with water is pretty obvious at night, especially if it's near a streetlight; I see it, so I can avoid it. But it creates a new challenge - the glossy surface applies to all, making it impossible to differentiate an indent from an ankle-breaker. More data, and the problem is solved, but now I have a new problem, which will require more data; I make do in the meantime and avoid every puddle, just in case.
