I'm sure Earl of any of the others that have worked on the C&TS can answer better, but what I gather, the best locomotive usage is a loco making a one-way trip to Antonito one day, returning the next day and the third day is for checking the loco in Chama.
3-locos.
There are two train sets - both about 14 cars if I recall. If you put 463 in the rotation one day, the consist has to be shortened. This increases costs.
If you have 4 or more locos, it works fine if 463 is staged as helper only when needed. There may be issues with a loco kept hot for 4 days between usage - I do not know. As a helper, there is less of an incentive to restore 463 since it is not flexable enough to use in the regular operating pattern.
463 could work fine out of Antonito with the 1.42% grade BUT the facilities in Antonito are not set up for basing locos there. The coaling is based in Chama. The major shops are there also.
"Why do you always have to do the ecomomics as if every locomotive has to pull a 14 car train?"
These locos need to earn their keep. That means either making a profit or reducing state support. This means economics. Sorry if you do not like it, but economics is there regardless.
As far as ALWAYS - I've never tried to explain the economics of the operation with a 14 car train before. I do not think I've ever tried to explain the economics before. Please be sure of your statement before throwing stones.
If you own the RR like Al Harper owns the D&S, then its your call and the heck with anyone else.
DvV