I think maybe going down that rabbit hole is worth the trouble. Tossing a couple of data points out that don't mention a turntable in the shed without adding those that do begs a response. It just so happens I've been digging into the St Elmo to Gunnison line for the past month: photos, newspapers, company papers, forum threads and all the well-known books. Looking into a possible layout concept, Parlins to Quartz in about 1892, which expanded into the always-fascinating tunnel history. Then a day or so ago I stumbled on the long thread from December you mentioned and read through it. One thing is clear: Rick Steele pretty well made the case for the turntable at that time. To me the big question is when it was installed.
In 1882 there is a reference in the Pitkin newspaper to the construction activities at the Tunnel (see Edward's South Park Documentary History V1 for this article). The shed's dimensions are given and are a hint (clearly a 50' turntable as used elsewhere on the DSP&P would fit perfectly) and the reporter also mentions a planned coal bin, water tank and turntable inside. The building was clearly designed with a turntable in mind. But did one get installed? No mentions I've seen at that time. We do know that there was a turntable pit in the shed--both the lawsuit of the cook falling into the pit around 1897 and the excavation in the 1970s that found the pit are pretty solid evidence of intent and actual construction. But the turntable--that is more elusive and I've not seen anything affirming there being one during these early days.
In July 1885 several papers mention a turntable having been installed at St Elmo (See Poor and Edwards). 2+ years of operational reality likely drove this decision. St Elmo became the end of line each year from as early as December to as late as August due to snow closures (search "alpine" in the Colorado Historic Newspapers online, many articles annually of closures). They needed to turn engines and I am increasingly of the belief that Hancock had no wye until the C&S built one in 1902 (Edwards)--someone correct me if I'm wrong on this, please! The line from St Elmo to Hancock in winter was pure hell to operate so St Elmo became the logical end of line and point to turn engines. What was the source of the St Elmo turntable? Was it the tunnel turntable moved down to St Elmo? Was it a turntable meant for the tunnel, but uninstalled and stored on the ground? Unknown to me. I have heard that a reference to this turntable is in an 1883 Employee Timetable I've not seen--the one in the Pictorial Supplement doesn't list facilities. If anyone has the timetable I'd love to see it.
The 1886 UP B&B book lists a 50' iron turntable at St Elmo and none at the tunnel. (Thanks to Rick Steele for graciously sharing this on the C&S forum)
In 1889 the UP authorized installation of a turntable at the Tunnel but there is no evidence that it happened. (Edwards)
In 1890 the newspapers buzz about activities at the tunnel including a planned move of the St Elmo turntable to the tunnel (CO HIstoric Newspapers). In fact the 1886 UP B&B book has handwritten notes to the effect that the Woodstock bunkhouse was moved to the tunnel to become the telegraph office, and a section house and bunk house were installed INSIDE the engine shed, all in 1890. The hoped-for handwritten note in that book that the St Elmo turntable had been moved to the tunnel isn't there.
Meanwhile, the Alpine Tunnel line was already in deep trouble. The tunnel was a grotesquely serious money pit, both in initial construction and ongoing maintenance. Gunnison's business prospects had withered, with coal and hay being the primary traffic east and empties making up a good portion of trains westbound, if I can believe what little data is out there. 4 engines to haul 12 cars + combine out of Pitkin to St Elmo was expensive, with engines apparently consuming 15% of the load they hauled to make the trip (Edwards and I think CRM 12--plus photos). Winters shut the tunnel for anywhere from days to months every year (lots of newspaper accounts of this). By 1887 5-6 month winter closures were becoming normal. Why the UP suddenly sank money into the tunnel facilities in 1890 when things were looking so bad is an interesting puzzle--but maybe things didn't look so bad for some reason at the time. I lean to theorizing the 1890 activity was an intentional consolidation of Alpine tunnel station's functional operations into the engine shed as a survival tactic.
Then the winter of 1890-91 hit and after struggling to get some 50 stranded full coal cars out of Gunnison over the line after suspending normal ops the UP threw in the towel. The tunnel wouldn't be reopened for 4.5 years.
In October 1893, in the middle of this abandonment, the DL&G was inventoried and included is a list of each engine shed and turntable on the line by location (Thanks to Rick Steele again for sharing this information on the C&S forum). At Alpine Tunnel, a 50' iron turntable installed. That seals it: A court-mandated inventory is pretty solid proof. But when was it put in? It seems likely there wouldn't have been any motivation to install a turntable between 1891 and 1893 on the closed line--but maybe there was in 1890 during the spurt of activity and we don't have records of it. And at least one photo from DL&G days (likely mid-1890s) show an empty turntable pit at St Elmo, the oft-referred-to source for the tunnel turntable (see Digerness Vol II).
We know there was a turntable pit and we have solid reference to a turntable installed in 1893 and that the St Elmo turntable was missing . It remained there when the engine shed burned in January 1905, later being retrieved and moved to its final location on the spur off the west portal cut. Perhaps the 1906 B&B book's accounting occurred before it was retrieved? I don't have a copy to comment on it. Regardless, I think the case was made back in December.
