I used to work for BNSF, I'm well aware of how those programs materialize on the private end. Sometimes states will chip in, but it's mostly on the line owner. You can't just install a crossing anymore. They're wired into national and global networks that are part of track-side overhauls. Additionally, when AMTRAK goes over BNSF lines (at least when I worked there) you don't have automated train control (which is really braking). A signal is a good first step, but if your goal is to really put a dent in these kinds of incidents then it's a lot of on-going cost - mostly born by the tail operator because they're the ones that lease access to the lines.