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, n/adj a child who is in the earliest stage of extrauterine life, a time extending from the first month after birth to approximately 12 months of age, when the baby is able to assume an erect posture; some extend the period to 24 months of age.ee also growth. large-for-gestational-age infant a preterm, term, or postterm infant who is above the 90th percentile for gestational age in head circumference, body weight, or length. low-birth-weight infant one that weighs less than 2500 grams at birth.