This generally historic drama depicts the railroad issue of the day circa 1910-1915, when railroad signals were changing from the moving arm semaphore to simple color lights (red and green) and railroads learned many engineers were red-green color blind. This shows people losing their jobs and even a head-on collision, depicting the effect of these historic railroad improvements.
The Block Signal
Silent film drama depicts effect on everyone as color blindness becomes a concern due to "railroad improvements", the color light block signal.