Wooden Stop Look and Listen R/R Crossing Sign

This Railroad Crossing sign was in a barn I bought; I believe it was Boston and Maine Crossing Sign. It's quite large - each side is one piece of wood 11 1/2 inches wide and 8 feet long. The paint is original and the letters are slightly raised because the black paint weathered less than the white and they stand out a bit. The sign is two-sided and I remember seeing them when I was young - a long time ago!

What can you tell me about its age and value?

Thanks for your help.

Choochoobob