On a related note, I own 2 rental properties that have the L running directly behind them.
One of them is separated by a decent sized yard, so that one hasn't been a problem.
The other one is on N Bissell in the Ranch Triangle area of Lincoln Park and has the L running literally right out the rear window.
Despite being a kick ass apartment, I have often had difficulty getting the top floor apartment rented. My leasing agent tells me that countless prospects love the apartment until they get to the bedroom next to the L. Then they stop, stare out the window, and watch the L go by over and over again.
Afterwards, they leave and never call her back!