Dave Dye (ROW Explorer) has done several excellent overlays of the Red Mountain line using both evaluation maps and Google Earth type of imagery. Use the search function--one that came up is:
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davesriogrande.net]
The Row from Silverton town limits north is not under 550 and can be hiked for most of the way. It crosses 550 at Burro Bridge (shortly before the turn off for Ophir Pass) and then is on the lower side of the highway to Chattanooga. It can then be followed pretty much all the way to the top of Red Mountain Pass, though not much of it is safe to hike at this point. The ROW is directly under 550 as the highway crosses the summit, then reappears as it goes around Red Mountain into the town site. There is a lot more to see on foot than from the window of a car. Take along a copy of the Rainbow Route for reference and it all jumps out at you.
Fritz