Over 50 years ago I hiked with my dad the entire abandoned GN route over Stevens Pass during several outings. Our hike would be better described as an exploration at the pace we moved, while examining the details along the route. Back in that time there was no access road close to the lower Martin Creek trestle. With the west end concrete abutment being out of sight, the ancient "NO Trespassing" warning sign was still standing guard at the long gone trestle. The following year it had vanished, though decades later I heard from a coworker that he knew who had removed the sign and that it was preserved.
We also hiked all of the 1892 switchback grades that were left. On the east side of the switchback route, long sections still had ties in good condition. I tried to pull a spike from one, but after expending much effort with tools nature provided, I remember thinking nothing short of a spike puller is going to remove this.
Sometimes the thought of hiking the line again crosses my mind, but have not acted on it, preferring to remember the nearly untouched ruins as I first saw them. We never met anyone else exploring the area back then, being long before it evolved into a hiking destination. No longer a hike of solitude, with I imagine plenty of rules of conduct, it would feel to me more like Disneyland and it is probably best I stay away.

The linked film was the first I have ever seen of this old GN line in operation. I have heard word of additional footage but not where to find them. Most likely archived and not readily available.