Keep looking for the free lunch California.
This was looked at in the 1980s and discarded as impractical to install and maintain.
Besides, you also have a problem with one statement in the article. - captures the ambient energy generated by moving cars - This is California traffic we are talking about. During rush hour top speeds are close to 10 mph. How much energy will you get?
It is just another way Californias are trying to ease the guilt of living an unsustainable life style.