This is the UP Warm Springs Sub, which connects Niles Junction in Fremont to the Coast Sub in San Jose, just west of downtown. Before the recent changes, the only trains that this line would see were 2 daytime locals that serviced a number of industries around the South Bay. There was no such thing as a through freight on this line, even though logistically it makes sense since this is a direct shot from Fremont/Warm Springs/Milpitas to points south. I believe the track is only good for 10-25 mph south of Milpitas.