As mentioned earlier, the Silverwood connection just west of Summit allows UP trains in and out of the L.A. basin (including West Colton Yard) to use company-owned track instead of having to rely on trackage rights and delays over the competition's route through the majority of Cajon Pass. It allows better routing (from UP's perspective)in and out of West Colton Yard and to/from the Sunset Route toward Yuma. However, UP's ex-SP main through Cajon is mainly single track (compared with BNSF's 2, now 3 main tracks), so there's only so much traffic UP can pull off BNSF without creating their own logjam. Silverwood is oriented to make the same connections in the same direction as the older Keenbrook connection, but Silverwood is much better aligned in terms of grade and curvature. And being near the top of the hill, it keeps UP trains off BNSF as much as possible. Now that BNSF has that third main, it should be interesting to see if the added capacity brings more UP trains back to the BNSF side of the pass.