As you've already learned, road access from Lyon's Ferry/Joso is usually gated shut. This is due to the Marmes Rock Shelter more than the railroad. Marmes itself is one of the biggest geological stories ever, but its details have been hushed by politics, PC, special interests, etc. A couple of good books on the subject, including one by the man who did the initial forensics on Kennewick Man. Long story short, they found evidence at Marmes, as they did with Kennewick Man, that people resembling European descent lived there long before those resembling Asian or Native American descent. Marmes, Bretz and his Missoula floods, and Mt. St. Helens have made the Northwest a hotbed of discovery that's turned the old science world on its ear. Between that, and the general desire to preserve what's left of the site (much of it flooded after the Snake River dams despite efforts to protect it with a dike), they used to chase down and question anyone entering that area. Now that it's gated, anyone entering by vehicle is assumed to be OK and usually left alone.

From Joso's north switch, it's a tough climb up the dirt and talus slope to the top of Tunnel 10. Looks like easier hiking around the east side of that hill, but it's just plain easier to hike south from Palouse Falls. The dirt road along the west side of the railroad from the park will get you part way in by vehicle, but much of it is just walking along the same trails used by deer, antelope, and range cattle. Tight views of tunnels 10-14, some with nice views looking down onto the river as well.

North from Palouse Falls, you do have a short trail that eventually leads to the right of way, plus a rough bit of trail for the first mile or two on the ridgetops along the west side of the track. With written permission to be on UP property in hand, it's a snap to walk the right of way, but certainly nothing that I can recommend to anyone. River bends in and out of view for the first mile north from the park.

Just north of a private road bridge along a broad curve, there's a crude barbed wire gate on the west side of the track. Pass through here, find the narrow gap through the rimrock, and you're up high on the west rim of the canyon for fantastic views looking down at Park siding and the short bridge over the Palouse River. Haven't done so, but looks like you could walk this clear north to the Little Palouse Falls. North of the bridge, at Park siding, you can climb to the east rim of the canyon. There's a network of dirt roads up there on private range land, which you could probably access with a little sweet-talking with the locals. Nils Huxtable posted a shot of some UP special taken from up there a few months ago.

Otherwise, your next point of access is north of Tunnel 15. There's a gravel road that brings you to a crossing about a mile north (geographically northeast) of the tunnel, but the past couple of times I was there they had it gated shut about a mile before the crossing. Beautiful shooting on both sides of the tunnel if you can get there, and plenty of trails up and over the tunnel and surrounding ridges. Killer view looking south into the canyon too.