Much of New York's subway system runs underground, but some routes operate on elevated tracks not unlike Chicago's. As anyone who lives along CTA lines knows, the noise of the trains is a constant, if distracting, companion. Ironically, with the MTA transit strike continuing, some New Yorkers find themselves more distracted by the quiet. Which is just one more reason to hope Chicago's not faced with the "nuisance" of noise-free living any time soon.