What metaphors are used in We Were the Mulvaneys by Joyce Carol Oates?

Judd recounts, “For all of my childhood as a Mulvaney I was the baby of the family. To be the baby of such a family is to know you’re the last little caboose of a long roaring train.” ‘The little caboose’ is figurative of the ‘last born’ position whereas ‘ a long roaring train’ exemplifies Judd’s older brethren. The rhetorical ‘little caboose’ gathers that Judd was overly adored by the intimate household members.