Stuck at an intersection, you always watch unfold the fundamental problem of traffic.

On green, the first car accelerates, and then the next, and then the next, and then the next, and then the next, and then you, only to catch the red.

Had the cars accelerated simultaneously, you would have made it through.

Coordination, not cars, is the problem, because we are monkey drivers with slow reaction times and short attention spans.

Even if we tried, getting everyone to press the pedal on 3-2-1 now would be challenging.

This discoordination limits how many cars can get through an intersection, and when one backs up to the next,

that's when city-sized gridlock

cascades happen, taking forever to clear.

In general, more intersections equals more discoordination, which equals more traffic.

This is the motive behind big highways.

No intersections.

Splits and merges, yes, intersections no.

No stopping, no coordination problems, no traffic.

Well, that's the theory anyway. Intersections outside of a highway will back up onto it,

again, because human reaction times limit how many cars can escape the off-ramp when the light changes.

But even without intersections, there would still be traffic on the highway.

Traffic can just appear.

Take a one-lane highway with happy cars flowing until a chicken crosses the road.

The driver who sees it breaks a little. The driver behind him doesn't notice immediately and breaks a little harder than necessary.

The driver behind him does the same until someone comes to a complete stop.

And oh look, cars approaching at highway speeds must now stop as well.

Though the chicken is long gone, it left a phantom intersection on

...