This route would include the Union Pacific route of Cheyenne to Laramie on their Overland route. As well as a few good freight locomotives and passenger locomotives. Such locomotives could include the Union Pacific GTEL third generation , Union Pacific Big Boy steam locomotive , UP 844 , and perhaps include the UP SD90MAC . I will include all the different sources that were used for the following attached images and map of the suggested route: The length of the route would be about 48 miles in between Cheyenne and Laramie. Some services that could be included would be some steam excursion trains with 844 and 4014 along with optional freight service with the steam engines. And for the GTEL and SD90MAC would be freight including intermodal containers, grain cars, coal cars, or refrigerator cars.
What about an ES44AC or ET44AC for heavy freight, a 3GS21B Genset switcher, and maybe an SD40-2 or SD45?
48 miles if you go straight from Laramie to Cheyenne. There are lines that go to industries in the area that increase the size.
Sherman Hill in TS2018 is enough. It's literally the only route made for modern Union Pacific, so its been way overused, and I am tired of it. I want to have Union Pacific somewhere other than the line I've driven over 100s of times with dozens of locomotives.
Another Union Pacific route I had an idea for was the Wasatch Range between Weber and Echo canyons in Utah. I'll do some research on it.
But Sherman Hill redone in the great graphics of TSW would be something to behold. The majesty of the area seen in real life can not be described - the term "Big Sky" country is very appropriate for the entire high plains region as it runs the front range of the Rockies. Not saying I wouldn't mind other UP routes but Sherman Hill in TSW graphics would be a buy for me for sure.
As pschlik said, Sherman Hill was very overused in TS1 and a different UP route should probably be created instead. In my opinion something like Cajon Pass (which wasn't used as much in TS1) or the Moffat Tunnel Subdivision (which wasn't featured in TS1) should be made for TSW before this route.
Cajon Pass is part of the BNSF transcon. The UP route just a few yards away through the Palmdale cutoff is not appreciated much, but it's also not very interesting. If one were to do Cajon Pass, it would be senseless to not make it a BNSF route.