Although I have enjoyed Microsoft Flight Simulator for years, not all of my enjoyment has been from flying the planes. I have also made numerous repaints, and added literally thousands of new AI traffic routes. I've also modified all of the built-in ones, although not always with precision. This video summarizes how to build AI Traffic files using TTools and Notepad.

TTools can be acquired here:

flyawaysimulation.com/downloads/files/1231/traffic-tools-v202