It's interesting that many/most line relocations are made to reduce curvature and/or shorten a route. When the Western Pacific was built, it was actually about 3-4 miles shorter than it's pre-Oroville line change length of 928 miles from San Fran. to Salt Lake City. Both of its present "loops" (Williams--the helix in the F.R.C. and Arnold--the horseshoe at Silver Zone Pass, NV) were originally by-passed with short segments of 2+percent grades but since the W.P.'s construction bonds specified that the route would have a 1 percent maximum grade, the current alignments were constructed as part of the final and approved route. Why the UP has still not put back in the Williams by-pass, I can't figure out. That plan was done in '84 and was actually budgeted (but later cut) a year or so later. I have an ancient photo at home that shows the old by-pass track still in place after the loop was built. Williams Loop is dang near exactly 1 mile around.