One inexpensive suggestion which would help to prevent pedestrian-bicycle-rollerblade accidents is to have one way directional travel restrictions.
Cyclists and roller blades would only be allowed to go in one direction (clockwise or counterclockwise), and walkers in the other. That way the walkers would always see what's coming in their direction and have time, if necessary, to avoid a collision. Appropriate signs could be posted along the trail with the proper instructions, much like the running and walking tracks in some of the local gyms.
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