Amtrak's Coast Starlight out until feb 28, story from the SF chronicle...

http://sfgate.com/cgi-bin/article.cgi?f=/c/a/2005/01/22/BAGG7AUGGH1.DTL

Why isn’t the Zephyr rerouted over the UP between Denver and Salt Lake City?

Based on the story linked above it appears the big problems are west of Salt Lake City? Maybe they don’t feel it is worth the detour time and costs?