Western Railroad Discussion > Questions about Fontana, CA - Kaiser and CSI

Been watching some videos on the 'Tube of UP LOH45 --- the Kaiser Local that switches out California Steel Industries in Fontana.  UP trackage comes in from south end under the 10 freeway from their Kaiser Yard.  BNSF also serves CSI via the Metrolink San Gabriel Sub on the northside of the CSI property...   According to the Freericks book (Southern California Local Freight Trains 2015/2016), the BNSF "4th Kaiser" serves CSI, or at least did when the book was published.

The same track, on the west side of the CSI property that UP uses, connects with the BNSF on the north side of the property.  

My questions: is there a deliniation on CSI property where the trackage switches from UP to BNSF?--- and, do the two railroads ever exchange cars on CSI property or does each railroad strictly handle their own carloads and empties?

Thanks,

Bob

Only info I can provide is UP only goes directly into the CSI yard from south with BNSF using the long lead between Metrolink and CSI yard on south side of plant. When either does this I do not know. BNSF slab train as well as coil train both go in from Metrolink San Gabriel Sub.
JB