Good points. I have a suspicion that somewhere BNSF has engineering studies, etc. for a lower Stampede tunnel. I've heard NP did some of these a long time ago... In the long run, a new bore might make more sense. Of course, the Csacades can be problematic to tunnel -- old faults, water, etc., which is why they can't simply lower the floor of the exising tunnel.

While the line is fairly near river level between Easton and Cle Elum and E'burg, it isn't exactly flat. The area between Easton and Cle Elum is deceptive, but the line does have a 2.2 grade, then around 2.7 to the tunnel itself.