I think the running/walking thing could be easily solved. Now the trail is somewhat narrow, but it's doable if there were a few little signs just telling runners to stay toward the middle and walkers to keep right.
Runners should be able to speak.. "Coming behind you' or something like that. Bikers probably ought to stay off that trail for safety's sake. It's quite narrow..Besides they have all kinds of bike trails now....and I never see people on them.