The police patrol my local path with police cars once in a while. Bicycles during the day too. The local citizens group uses cell phones. Each town does their own thing, my path goes through four towns and is also patrolled by the state parks division as it is a state park.
A little after dark a state truck goes down the path looking for anything unusual. The bike path is closed at sunset, but open to commuters. This gives the cops some options. I ride on it in the dark all the time. There were problems in the past but now with the patrolling there is never anyone around after dark. Just the threat of a possible patrol changes things a lot.
Suggest to people on the trail to always bring cell phones too.