Thanks for the responses, everyone. I was particularly intrigued by the PR handout, submitted by Larry Green, that was issued on the day the by-pass was opened:

The original Highway Bypass plan called for construction of four grade-separated crossings in addition to total reconstruction of the Goddard Avenue and I 25 Interchange.
Elimination of the three railroad grade separations and the Goddard Avenue/I-25 interchange reconstruction means a saving in overall costs as well as acceleration for the U.S. Bypass by one year.

After looking at some aerial photos, I can't quite figure out how the construction of the rail bypass eliminated the need for THREE or FOUR (as stated above) rail/highway grade separations. Goddard Avenue obviously needed a grade separation over the C&S and ATSF tracks near I-25, and that's what was built. The rail lines of both carriers are close to one another at this location, so one bridge probably would have sufficed. The ONLY grade separation that I can see that was eliminated by the construction of the rail bypass is where the C&S line starts climbing southward from the C&S station up out of the Pergatore river valley up to where the "old line" ties in with the new by-pass. On GOOGLE aerial maps, this would be a little bit north of the 200 block of residential Dale Street.