Any BNSF double - stack trains using Stampede Pass Tunnel would have to get up a running start; rather difficult to do on a 2.2% uphill grade in either direction leading to the tunnel. And they would emerge as a single - stack !!! The lack of positive ventilation and a grade that tops out in the middle of the tunnel, allowing smoke to remain there, would also be a problem.
Regarding BNSF using the Inside Gateway and Overland Route, I recall that BNSF gained trackage rights over the ex - WP line from Salt Lake City to Stockton, as part of " allowing " the EwePee to assimilate the Espee in 1996. Of course BNSF now owns the entire Inside Gateway route from Keddie Wye North to Klamath Falls.
Regarding a BNSF traffic meltdown, just today as I drove past Auburn, WA. yard, there were nine Northbound trains tied down. At least 7 of them appeared to be grain trains. While several might be MT's waiting for a re - crew to head East over Stampede Pass, that still leaves quite a few to move. Maybe BNSF is waiting for the ships to reach the Ports ??? Also, this collection of trains may be the legacy of the pedestrian fatality yesterday in Edmonds,WA. that shut down the Seattle - Everett mainline from 7:30AM to Noon.