when a automobile moves overe a wide, closed loop of embedded in a road surface, the magnetic field of the earth within the loop altered? is a pulse of current produced? can you cite a pratical application for this at a traffic intersection?

#1: yes; #2 yes, and (#3) you have probably seen applications at intersections. Many residential interesection lights only turn green for one direction when there is traffic waiting. It can also help tell lights to stay green until after all waiting cars have passed.