It indeed disappears into an underground pipe, but it does it in several spots. The channel doesn't all flow the same direction. 

I don't know if it's worth trying to map this thing in any more detail. It's basically an oversize gutter, and I expect it will all be reconfigured when the road goes from mostly construction access to public access for the new development here. I only want to keep it to avoid confusion with a sidewalk in aerial imagery. 

I'd be open to a more accurate tag.