There is a nice one by Funnnyfarm, <kuid2:411884:104461:1> 0 Great Northern Railroad Scenic Division 1893-1900 that goes over the Cascades from Wenatchee, Washington to Everett Washington. It is incomplete with unfinished roads and rivers, and while east of the summit is mostly complete, only a few miles completed west of the summit (Although a nice array of trestles, snowsheds a 180-degree tunnel!) The summit itself is a series of switchbacks, so the length of train is limited. Probably not great for running long modern trains. User Bravecat also uploaded copies without credit to Funnnyfarm, who left trains several years ago now.
There is also <kuid2:56511:535909:1> Montana Rail Link by N5VAV, which is in need of updating., Ditto for <kuid2:344263:100004:16> Montana Rail Link 12 MP v3.1 by jib228
DInorius Redundicus uploaded a DEM called <kuid:68213:100009> Patagonia That is actually the Columbia Gorge around Mt. Hood. I have tried starting to develop that as the Columbia Gorge, but have made little progress.
Sorry, none of the above are without considerable elbow grease to get up to shape. Unfortunately, the Pacific Northwest does not seem to be as popular as other areas of the US despite the gorgeous scenery!
EDIT: Corrected the reference to the second Montana Rail Link Route above.
