Yellow Means CAUTION APPROACH

CAUTION APPROACH

Signal Review:

Yellow / Approach:  The train must proceed at an intermediate speed, usually medium speed, until it reaches the next signal.  Not all railroads employed yellow for the approach indication.  The CNW back in the early days used a combination of red and green to indicate approach, as shown in the CNW rulebook section.  The use of green and red wasn't limited to railroad use, as many municipalities did the same with traffic lights, and I can remember traffic lights in New York City into the early 60's using red and green lit together to warn of the signal getting ready to change to red.

Slight horizontal movement at arm's length at right angle to track REDUCE SPEED