Re: Marker Light Qestion

I will try to answer this. Most marker lamps I have seen had three green lenses, a universal "clear" sign (D&RGW used amber color lenses), facing to the front and side. The one red lense faced down the rails behind the train. The lamps were designed to be move on its base, so they were reversible, though they were supposed to be placed tyhis specific way. The idea was that the engineer could see the green light and know when his train was in clearance. Same idea for those on the side of the train, as the green light indicated that the train was clear of sidings , roads, slow orders, etc. The red lense (a universal stop sign) faced behind the train, ostensibly to warn train movements approaching from behind to stop, as this was the end of another train movement. This basic signal syatem worked well, as long as the lamps were burning. The D&RG cabooses all had a clearestory box for a third lamp, but these were removed as the cabooses wre shopped after 1935. Most railkroads required locomotives to carry their own markers, for when they were running light.
There are plenty of tales in railroading about how a marker lamp prevented aome train from rear-ending another. During daylight hours a white flag could be employed. On lonely shortlines and industrial roads, marker lamps were rarely used. The ICC required roads that interchanged to strictly follow these rules, and this included narrow gauge. I nboticed that the SVR quit using markers on the trains around the time the 2-6-6-2s arrived. Hope this helps