I saw this on the Casey Trail, a lovely addition to Lake County's multi-use path system that opened this year. Lake County does trails so well. The Milwaukee Avenue underpass even has lights, for goodness' sake. Lights! In Cook County you're lucky if a trail underpass doesn't have six inches of standing water, much less any kind of illumination (reflections off the water don't count). And like the Des Plaines River Trail, the Casey Trail has quarter-mile markers. They're overkill for bikers but great for runners and walkers.