Traffic lights detect vehicles using a variety of methods. Check out this podcast from HowStuffWorks.com to find out how timers, inductive loops and other detectors keep traffic running smoothly.
Nov 21
What's the History of Skid Row?
<p>In downtown Los Angeles, the 50-block neighborhood called Skid Row is home to thousands of low-income people who live in tents, run-down hotels, and other temporary shelters on a permanent basis. Learn how Skid Row came about (and has persisted) in such a wealthy place in this ... Show More
11m 25s