>>2038870The biggest problem was that the original railway was built on a shoestring budget (it was basically the brainchild of one man, John Spreckels), hence the antiquated shit like wooden trestles and had the misfortune of construction starting just prior to the start of the Mexican Revolution. The fact that a significant portion of the line runs through Mexico complicates things further because piece of cargo and passenger traveling the full length of the Desert Line will have to go through customs inspections, twice, just to reach their destination.
Honestly the view is scenic enough that I think it would have potential as a tourist line, especially given that one of the termini is downtown San Diego, but you would need to essentially rebuilt the entire line before that became feasible. It doesn't help that the route is 70 miles long and the other terminus, Plaster City, is a complete shithole with nothing but Gypsum mining to it.
Maybe, you could do it as a hotel train where you depart in the early evening (5pm) running at a leisurely pace of >10 miles per hour (slow enough to make the journey around 14 hours and run comfortably), treat everyone to a fancy dinner, have the train turn around in Plaster City and return in the morning (7am). Restore some old heavy Pullman sleeper and dining cars and better yet, a working steam locomotive, and you might find a niche market for being the only play in the world where you can relive the zenith of American rail travel.