http://www.washingtonpost.com/wp-dyn/content/article/2011/02/01/AR2011020100021.html http://www.washingtonpost.com/wp-dyn/content/article/2011/02... They also

http://www.washingtonpost.com/wp-dyn/content/article/2011/02/01/AR2011020100021.html http://www.washingtonpost.com/wp-dyn/content/article/2011/02... They also save pedestrian and motorist lives.