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.
Newborn: usually birth to around three months. Infant: birth to maybe a year. Baby: This word is more general and includes both newborns and infants, and sometimes toddlers as well. Some people would stop using the word âbabyâ for someone around one year of age, but others would go up to about two years.