Everytime I got a cabride, on say N&W 611, or some other railroad, whenever they got a green signal, they would call it out in the cab as "Clear block", or "Clear". It was usually accompanied by a wave of the hand or a finger, so either the engineer,and firemans side were on the same page. This was never more useful than the time I rode the cab of Nickel Plate 765 (as C&O 2765)in 1993. We were doing 60-65 and it was near impossible to understand anything someone would say anyway from all the stack talk. Thats the kind of chatter I enjoy best!!!
By the way Norfolk Southern trains still call out the signals that they pass, and they are called on the radio to the dispatcher, along with the Milepost at the signal. This is quite useful if you have a scanner and are waiting for something. Its a good safety feature as well.
Greg