At least 90 percent of what you're hearing is Los Angeles MTA light rail. They've gone to digital and in some cases, digital on splinter frequencies. So, if your scanner or radio isn't narrow enough, it will bleed over to the adjacent channels on both sides. Why MTA was allowed to do this, I have no idea because it causes problems for the Class 1 railroads.

The BNSF car department repeater at Hobart has also gone digital. I think I'm forgetting an additional location at the moment...

In any event, there's still no reason to purchase an NXDN radio unless you want to monitor light rail or some guys changing out brake shoes. All of the mainline operations remain analog.