With human drivers: traffic light turns green. The first car starts driving. The 2nd car waits 2 seconds and then starts driving. The third car waits another 2 seconds (4 seconds total) and then starts driving. The fourth car waits another 2 seconds (6 seconds total) and then starts driving. etc.

With computers driving: traffic light turns green. All cars simultaneously start driving. It'd be like a train but without the efficiency.

Similarly, with human drivers: some jackasses drive into the box and the light turns red. Now perpendicular traffic is either fully blocked or must proceeed slower to maneuver around the jackasses. With computer drivers, they shouldn't intentionally break the law and they should have plenty of sensors to figure out that they cannot make it through the box.

Ideally, robot drivers will some day be better drivers than humans in all road conditions. They'll be able to coordinate fast lane merges and busy intersections by subtly adjusting speed without vehicles having to stop.

Imagine a busy intersection where all the cars fly past one another at 40 miles an hour without stopping but none of them crash. Humans can't do this, but machines could, if, and when the technology gets there. To be clear, there's still a way to go.

Traffic is usually caused by adding inefficiencies across a system with little slack - someone brakes too hard or too early, and if all the cars are stacked up, that one brake event can ripple through hundreds of following cars, getting worse and worse because each person brakes more. Self driving cars can perfectly sync up and move like a train. Theoretically there could be no traffic on highways if all cars are self-driving. Rarely is a highway so full that there couldn’t be more cars (eg. The entrance ramps are backed up) which implies the issues are related to the driving flow and not the capacity of the street itself.

Self driving cars don't panic and drive recklessly. I don't live in hurricane country, but most accidents around here are caused by drivers who are on their phones/spacing out or driving super aggressively.

Most traffic jams are caused by accidents or people slamming the brakes

In principle the driverless cars are more able to organize fleeting, operating in a way that's not actually practical if you don't share a single guiding directive.

I don't know that you'd ever see this in practice, but it's much more practical in theory for almost identical machines running the same software than for a bunch of humans in a variety of vehicles who've maybe only half understood how to do this.

Also, for this specific problem we know humans are idiots. They should all be driving an agreed route to the agreed evacuation point, but some real humans will decide they know a shortcut, they want to drop past Jim's place, or whatever. Just as there's a difference between what the protocol says happens when you have to abandon an aircraft on the tarmac versus the reality that people will decide they want to self-evacuate and they need their carry on bags and chaos ensues and maybe people die.

Same reason there's less gridlock when people obey traffic lights and other rules of the road and don't brake randomly. If every car on the road drove itself then there would never be traffic.

Well, probably not the current generation of driverless cars. Those would be a nightmare. Contrary to what some want to believe self driving cars do random shit all the time.

But in the future, if there is a coordination standard among driverless cars, that could allow much higher density at higher speed. Coordination standards + higher density of self driving should reduce the self driving cars doing random shit too.