The maximum (practical) speed depends on the cars per unit area, but drivers can voluntarily drive slower than this. By looking ahead at the conditions down the

The maximum (practical) speed depends on the cars per unit area, but drivers can voluntarily drive slower than this. By looking ahead at the conditions down the road, such as traffic jams and red lights, you will often notice situations where there are big benefits from slowing down more than you are forced to. Still, a lot of people don't do this, and it makes life harder for those who do. I'm amazed by how people will race to be the first one stopped at a red light. Doing a greedy optimization for maximum instantaneous speed can reduce the overall traffic speed, and sometimes even the average speed of the driver in question, increasing their own trip time. But the greedy optimization is still common to see.