I think I partially disagree and
@AmtrakBlue may have been most accurate. You can (from looking at street view) walk over tracks on the Powell bridge, but only on the pedestrian path hanging off the north side of the Powell bridge and navigating the steps up and down. At Horton and Powell but at street level head west there are a set of stairs to go up and over the tracks, then back down the stairs on the other side.
That pathway looks like an excellent, dark place for sketchy people to hang out on and less escape paths once you are on the bridge. Plus the staircases look quite tall. I don’t see an elevator shaft there. But I would say you should be able to walk across, and not have to go back east to get across.
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