Teresa, Welcome to the ACA Forums.
To answer you question, no gravel is present (unless construction is going on). As mentioned in the original thread, the traffic in Yellowstone is not bad if you manage it well. That said, the traffic on portions of the alternative are almost as bad, but at least you have a small shoulder.
I personally would do Yellowstone if you have not done it. I have done it 4 times so next time, I planned to take a similar alternate by breaking off the TA at the intersection of US-287 & ID-87 and take that to Henrys Lake then turning right onto US-20 and follow this the rest of the way as shown to Ashland. My alternative uses a more easterly route between Ashland and Tetonia using quiet county roads. After that, they are very similar except I use a little bit of quiet county roads where ACA keeps to the highway. See
https://ridewithgps.com/routes/36087038 to view my similar route.
Remember though that if you are using the alternative routes, traffic is almost as bad in places but the at least the sight lines are better. Plus, as mentioned in the other thread, ID-33 is fairly busy and is a definite climb with a somewhat narrow shoulder but once at the top, you have a bike path all the way to the intersection of WY-33 & US-191 on the west side of Jackson. City streets the rest of the way. Note that my route shows the route is on the road after you get past Wilson but the bike path is just parallel to it and I was lazy as I did not want to draw the path.
Not mentioned earlier is the traffic between Tetonia and Victor is actually fairly high too but there is a bike path beside ID-33 mostly between Driggs and Victor so that helps. The path may be finely crushed gravel in places but I think it is fully paved now, just not positive.
Hope this helps.
Tailwinds, John
