Actually Ralph if you look at the operating conditions on the line from Buena Vista to Pitkin, a turntable at both St. Elmo and Alpine tunnel makes a lot of sense.
The turntable at the tunnel (There was no place for a wye) is a good idea while the tunnel is open. The tunnel is at the top of the grade and it is a good place to cut off helper power, turn it, dope it, water and coal it and send it home or back to Como to help another train if needed. Why Como and not Buena Vista? Because of Trout Creek pass as well as the track back up to Alpine.
The turntable at St. Elmo is a good place to turn locomotives durning the winter when the Tunnel is closed. Remember, the Mary Murphy mine was just a few miles up the road from St. Elmo as were the Allie Bell and Flora Bell mines. These mines ran year around and were one of the main reasons in later years that the line remained open to Hancock. If you look at photos, you can find some of DL&G equipment on the wye at Hancock, in particular the short business car DSP&P/DL&G 025 that became C&S 912/089 although the wye might have been a late installation because Hancock shows only a Water Tank and no turning facility in my copy of UP Colorado Division Timetable 24, October, 1890.
You can see a photo of the Business car 025 and a Flanger next to it in Hancock on page 154 of Ferrell's
The South Park Line then go back and look at the track map of the area on page 84 and you sill see that the only track that the flanger could be on is the wye track. This was supposed to be during the snowplow trials of 1890. So you have to ask, was the wye built in Hancock to turn the snowplows and looked on as a temporary track until it became useful for the crews? Conjecture, for sure.
Please look at this from the perspective back then. That was a time when Customer Service was an actual driving force, unlike today where a single carload is shunned by the Class I's. Also Remember, after the St. Elmo turntable was yanked out and the Tunnel line abandoned, the (according to some sources) Gunnison turntable was installed in Romley to facilitate the turning of the Locomotive. There was definitely a turntable in Romley, but did it come from Gunnison? By that time, according to Sam Speas, the train originated in Buena Vista and ran up Chalk Creek Canyon to Romley three days a week and occassionally Hancock when the traffic called for it. The line over Trout Creek Pass was out of service around 1910-1912,
Then you have to remind yourself that not only did St. Elmo have a Turntable, but Hortense (later Mt. Princeton) had a Wye as well. The Wye at Mt. Princeton was ostensibly used to turn the power used on excursion trains to Mt. Princeton Hot Springs. If you want to talk about maintenance, the three turnouts and track on a wye are pretty high.
Like I said, don't look through today's perspective, look at it back then, before Hunter Harrison and PSR.
Rick