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.
infant. noun baby, child, innocent, juvenile, little one, minor, nursling, one who has not come of age, one who has not reached his majority, person under the age of majority, person under 18 years old, person who is not of full age, toddler, tot, young person, youngster, youth.oun baby, child, innocent, juvenile, little one, minor, nursling, one who has not come of age, one who has not reached his majority, person under the age of majority, person under 18 years old, person who is not of full age, toddler, tot, young person, youngster, youth.