WASHINGTON - Red lights are not only a nuisance when you're running late for work, they're also bad for the environment.
Stopping and starting a car eats up the most gas in your car.
Now, there's a smartphone app that will help drivers map out driving times, based on traffic signals.
Researchers at Princeton and MIT have designed an app called "Signal Guru."
Fast Company reports that the app uses a network of smartphones mounted on car dashboards to estimate traffic light patterns. The app takes photos of an intersection from approaching cars to estimate the time between light changes.
The app then calculates how fast or how slow a motorist needs to drive to avoid the next red light.
In a test of the system in Cambridge, Mass., SignalGuru drivers cut fuel use by 20 percent and were accurate within a range of 0.66 seconds of predicting when traffic lights turned.
The app is not yet available to the public.
WTOP's Del Walters contributed to this report. Follow WTOP on Twitter.
(Copyright 2011 by WTOP. All Rights Reserved.)
Don't look for the movie about Jodi Arias to be about her trial. (Video)
Ed Koch planned every detail of his funeral - except one crucial date.
James Franco wants fans to spot him half a million for a film trilogy.
Miss Utah's 2nd chance at the pageant answer that went viral. (Video)