The trouble with clean cars

Clean cars might be great for the environment, but they aren't always great for people who are blind.

Sure, blind people won't drive the cars. But they do rely on engine sounds to determine traffic patterns and decide when it's safe to cross the street.

And clean cars often are just too quiet.

"Hybrid and electric cars can be dangerous for all pedestrians, but they are particularly hazardous to the blind because we rely on traffic noise to navigate safely and efficiently," said Dr. Michael Gosse, an engineer who's president of the National Federation of the Blind of Maryland.

The federation has sent letters to...