An app called RailMate was released to the Play store over the weekend, giving frequent transit travelers a way to check their normal routes for transit officers, police officers, rail staff, and dangerous commuters. You can filter results by the train you normally take or train stop that you usually jump on at. You can view distances between alerts using GPS and vote on posts for accuracy. Also, be aware that posts are deleted every 24 hours so that you will only see the most current alert info.
In a way, this reminds me of the police scanner and alert apps that have grown in popularity over the years. Like those apps, this will need participation in order for it to be effective. It’s completely user-driven, so unless other users are setting alerts, this app will be useless.