Why Do Snails Cross The Sidewalk?

I have the same question for earthworms, who with their even less keen sense of direction end up frying by the thousands. It's a rainy morning in Yorba Linda, so this guy has half a chance, although he altered his vector after mistaking a crack in the sidewalk for the promised land. On a hot day he'd end up baking in his shell for sure. Have you ever helped a snail reach his destination?