Vertical (R,Y,G) signal. What was the first year they were used? On any railroad? Thanks
Sometime after about 1910, before that they would have been white-green-red.
My P&R 1922 rule book has 3 color vertical signal heads in it.
Most of the other rule books I have show semaphores until the late 30’s to early 50’s when more aspects with just color lights are shown.
You can’t necessarily assume whether the heads are searchlight of 3 color just from the rule book, because they may just show the color lit. In the case of the P&R it is clear for the diagrams that they are 3 color siignals.
perfect! and thank you.