Getting Started With Traffic Simulation in JavaScript

I am going to be asking a lot of questions in the upcoming months. For my ninth grade science fair project I would like to create a traffic simulator in order to test whether or not interconnected communicating traffic lights can increase traffic flow. I have a couple of generic questions that I need help with...

• How would I represent roads?
• How would I make car follow a road?
• How would I make a car switch lanes or roads?

I am not looking for specific code, just good pointers and resources to help me get started. Any help is appreciated, C.Ruhl.

PS I am only in high school so no advanced math notations please :)