BNSF does have a way from the bay (Richmond) to the overland. Its a relativly straight shot to Stockton. Then on to Sac-FRC/Donner. And I would say almost many trains leave Stockton going north as do going south. There are at least 2 overland trains a day plus extras that are becoming more common. Then there are up to 12 trains a day on the highline/Oregon trunk. I wouldn’t call that small potatoes.
And the UP does send a lot of traffic over the loop and on east. For traffic in the San Joaquin valley its a shorter route with much less hill to climb to get back east.
I think the trackage rights that the BNSF holds Sac/Den on the FRC is only for traffic originating & terminating in Sac no overhead traffic allowed. The FRC tape I have says that.
The Trains magazine about the SJ valley shows that traffic destined for the midwest & E/coast uses the Donner or FRC exit.
I donot disagree that the UPRR does use the loop but I suspect if somebody sat there say for a week 24/7 the BNSF would weight in at at least a 2 to 1 winner. [:p][:)][:D]