Who is Miss Subways from A Coney Island of the Mind, Poems and what is their importance?

Miss Subways appears in Chapter 2: Oral Messages, in which, she rides the Times Square Shuttle back and forth at four a.m. She has plugs in her nose, cut up arms, and a black weed in her hand. She is wearing sad slacks and a matching handbag, and she hangs onto the iron rings with her arms....... a ride into death and darkness.