Chris - I think it may depend on what period of history on the D&S and the DRGW. It is clear in the current D&S(2017) timetable regarding these restrictions, but reviewing the historic D&S Timetables I have (1-7 and 11), I can only find it mentioned in the current 2017 Version (11). In this case, it does allow K-28's to doublehead across the bridge at MP 452.42, but not the highline bridge. I am sure this specific language was introduced sometime after 2002 in one of the timetables I am missing. The last DRGW TT No. 4 (1980) that shows the Silverton Branch, double heading was
forbidden on the entire branch...period.
With that said, as an employee on the D&S (1981-86) I only remember cutting off before double heading across the highline bridge, We did doublehead across all the others. Double heading with only K-28's was the norm and I only remember one time during my days there that a K-28 was double headed with a larger locomotive. The K-28 was cut off at the highline in the case. In time, the highline bridge was worked on to handle the bigger engines and maybe for a time, doubleheading K-28's were OK. We might of had a General Order that addressed this that was in effect for a long period of time, but my memory is fading about those years.
As Jerry says, the older DRGW Timetable regarding the narrow gauge "in the day" were very specific about this.
It is interesting to note that I was the fireman on the road engine in your photograph...but I can't remember...if you have asked me, I would have said we cut off the helper, but your photo says otherwise. Of course, if the boss tells you to do something (regardless of rules)....you did it in those days.
MD Ramsey