I've been biking on this trail for over 10 years, and have never had an incident other than being stared at by a coyote and almost running over a snake. That said, I simply wouldn't walk on this trail alone. As others have said, the trail passes through some fairly isolated areas where you're liable to encounter some sketchy people living under bridges and what-not. I still bike it from time to time, because it's easier to find another cyclist to keep in view while traversing the sketchy areas. This would be a nice trail without all the negatives from being in a large urban area, such as trash, graffiti, and potential for crime.