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.
Answer: On this site, the word baby means any child from birth to age 4. Newborn refers to babies under three months of age. Infants are babies from three months to one year old.Toddlers are babies from one year to four years of age.nswer: On this site, the word baby means any child from birth to age 4. Newborn refers to babies under three months of age. Infants are babies from three months to one year old.