Understanding Cajon Pass traffic?

I have been tinkering around with the Cajon Pass route since I first got Rail Simulator hoping to someday enhance it for more activities. I know there are things missing that could add some fun.
My question today is not about infrastructure though... it's about the traffic... UP vs BNSF. Since I began learning in this trainsimming community about three years ago I have been led to believe that UP and BNSF are fierce competitors who don't like to share right-of-ways or help each other in any way. However, everywere I look on the Web I find pictures of BNSF trains on the UP track over Cajon Pass. On Google Earth, you actually see trains parked and waiting in the big crossovers (which EA Games left out) from the UP double track over to that "highline" track up the hill. I found those same situations in photographs on the web also. Before this I had the impression one line was UP and the other was BNSF and never the two shall cross!
Can anyone clarify for me just what the real traffic currents/rights/paths are out there??? I'm confused. The problem is I don't know exactly how to incorporate that highline track and exactly what traffic will flow over those crossovers. Also, I am trying to create some "protofantasy" passenger traffic on the route (hint: it's got a high-speed tunnel!) which is almost nonexistent in the route's present condition... but there IS a hint of it. Can anyone fill me in on just what IS going over that route? I'm guessing one or two Amtraks a day maybe???
Thanks guys!
Tori
P.S. Don't expect any release on this work anytime soon (or at all?); it's just something I tinker with from time to time.
My question today is not about infrastructure though... it's about the traffic... UP vs BNSF. Since I began learning in this trainsimming community about three years ago I have been led to believe that UP and BNSF are fierce competitors who don't like to share right-of-ways or help each other in any way. However, everywere I look on the Web I find pictures of BNSF trains on the UP track over Cajon Pass. On Google Earth, you actually see trains parked and waiting in the big crossovers (which EA Games left out) from the UP double track over to that "highline" track up the hill. I found those same situations in photographs on the web also. Before this I had the impression one line was UP and the other was BNSF and never the two shall cross!
Can anyone clarify for me just what the real traffic currents/rights/paths are out there??? I'm confused. The problem is I don't know exactly how to incorporate that highline track and exactly what traffic will flow over those crossovers. Also, I am trying to create some "protofantasy" passenger traffic on the route (hint: it's got a high-speed tunnel!) which is almost nonexistent in the route's present condition... but there IS a hint of it. Can anyone fill me in on just what IS going over that route? I'm guessing one or two Amtraks a day maybe???
Thanks guys!
Tori
P.S. Don't expect any release on this work anytime soon (or at all?); it's just something I tinker with from time to time.