I have never heard of this expression before but I'm guess it refers to the fact that nowadays trains use digital signals instead and as a result they don't have caboose/brake van anymore. So (without context), it probably means that the person who said it believed that caboose is important and safer than digital signals? Or the trains will be safer to have a live human being watch out for it ?
Definition of baby. plural. babies. 1a (1) : an extremely young child; especially : infant (2) : an extremely young animalb : the youngest of a group He is the baby of the family.
An infant is a baby. When you were an infant, you weren't able to walk, talk, or feed yourself (but you had a pretty mean burp). Infant is most often used for a very young human, but you can also use it to talk about animal babies. People are considered infants from the moment of birth until approximately one year old, an age when many babies are starting to walk and talk. At this point, they're commonly called toddlers instead of infants.