About 10 years ago, I took the Empire Builder from Chicago to Seattle. West of the Twin Cities the route was single track. At that time the Northern Transcon seemed loaded with traffic. Every siding was occupied. On the other hand, the only time we went into the siding was to let eastbound EBs pass. I got the impression that BNSF has to bend over backwards to accommodate a 79 mph train like the EB. Probably few other passengers noticed. (BTW, an Amtrak sleeper rides smoother and is a lot quieter today than was a Pullman on jointed rails in the ‘50s.)
I noticed in a story in today’s Chicago Tribune
http://www.chicagotribune.com/business/chi-0411270233nov27,1,5900245.story?coll=chi-business-hed
(a story about diverting traffic around Chicago) that Wal-Mart and other large retailers have started to reroute deliveries to Northwest ports to avoid the congestion in the L.A. area. Does the Northern Transcon have excess capacity to accommodate the extra traffic? Or has BNSF been quietly upgrading it concurrently with the southern route since I last saw the Northern Transcon?