Avoiding Left Turns

An example of a simple rule for a much more complex task.  How many of these rules are there, and how many sub tasks exist?  

Teaching a Driverless Car to Turn Left
The Boston Globe, Hiawatha Bray

Getting driverless cars to make safe left turns at intersections is a key challenge for engineers, as they involve both psychology and technology. Toyota Research Institute CEO Gill Pratt predicts enabling self-driving cars to safely make left turns will take five to 10 years to perfect. The challenge lies in autonomous cars' current inability to reliably guess the future actions of other cars and pedestrians. "Some driving is really hard and the hardest of those hard cases involves predicting what other human beings are thinking," Pratt says. Left turns are expected to be easier when automobiles start communicating with each other, and the National Highway Traffic Safety Administration in 2016 proposed a rule requiring all cars to have installed vehicle-to-vehicle radio systems in about five years. Avoiding left turns whenever possible is a strategy driverless vehicles may adopt, as it saves fuel and reduces accidents and waiting times at intersections ....  "