Further on dating. Note the end window on the engine shed, partially boarded over. Look inside and you'll see a structure. In the 1886 UP Bridge & Building book are notations that in 1890/91 a section and bunk house were built inside the engine shed, significant sized structures that sat on either side of the turntable pit on that side of the structure. Exactly what they looked like is unknown--I'd speculated they were made up of connected boxcars set end-to-end and side-to-side but the dimensions don't quite work out for that. These were lost when the shed burned. So, beyond knowing the photographer and rough date, the existence of these structures suggest a post-1895 engine shed, after the DL&G re-opened the tunnel after 4 years.