The CTA, having installed signs and special metal rings surrounding the emergency contact buttons that are in each train car, have now added an additional feature to identify the buttons: blue lights above the buttons. The blue light should make it extremely easy to spot the buttons, which were installed to allow passengers to contact the train driver. (But only in emergencies! So don't be pushing the button just because you're lonely and need someone to talk to. And if you accidentally push the button, just let the driver know it was an accident.)