[larkery]

I agree with your scepticism about solving the commute traffic with a self-driving silver bullet. The research for traffic flow [1] says that, with human driven cars, a slice of a 4m wide lane will pass about 1000 people/hr in cars, about 7000 people on foot or bicycle, and about 10,000 people by bus.

That means that to get competitive flow with buses, self-driving cars need to deliver a tenfold improvement in flow. Since in traffic cars are quite tightly packed already, you probably can't get much from putting them closer together, so even if self-driving magic gives you two doublings of flow on its own you still need to more than double the speed limit to compete. I can imagine this working only on roads dedicated to self-driving vehicles, with no pedestrian crossings, so now self-driving cars benefits only materialise if they eat up a chunk of the public space.

You might get a bit of improvement from vehicle sharing as well, but it seems like a really complicated way to attack a problem that already has an OK low-tech answer, at least in high density areas.

Where I live the census says that about half the commute journeys in the area are less than a few miles, for which cars of any sort seem ridiculous to me, for the able bodied. For those who aren't able bodied or have a long journey all the able bodied car users on short trips are using up a scarce resource that they need!

Throw in the health benefits of active transport, and the health cost of particulate emissions (still a problem with electric cars, since a decent chunk comes off tyres and brakes) and it looks like a wash to me. Then again I am one of those awful bike people, so maybe I miss the point.

[1] Litman 2017, Brun & Vuchic 1995 etc.

[abecedarius]

Outside of NYC, in the U.S. public transit in my experience takes two or three times as long to get you where you're going. Until the typical experience gets better or people get poorer, the resource efficiency won't matter.

[larkery]

I guess part of the issue here is that cars are a kind of coordination problem - if nobody else is using a car on the roads, cars are quite a good choice. They are fast and easy, and go where you want.

However, each person who uses a car creates some external costs (a high traffic factor / unit of person-flow) which are borne by all the other road users. Once people choosing the "defect" strategy (cars) have enough numbers, the "cooperate" strategy (not cars) gets broken for other solutions that use the road network, so the system fails to a bad equilibrium if there are enough defectors in the population.

[abecedarius]

Congestion pricing would solve that, and go nicely with robocars too.

(I'm not a fan of cars; I don't drive one myself. But I don't expect people to accept any less convenient and flexible solution.)

[StudentStuff]

The common American is getting poorer, but just like junk food and lack of exercise, people still drive. Other modes of transit may be much safer and healthier, but unless the common person is encouraged (whether that be with incentives to not drive, or tolls for driving) quite a few people will still drive.

There are a number of US cities that get most workers into the urban core besides NYC despite poor to middling infrastructure at best, but driving infrastructure dwarfs everything else, bike lanes are added only to diet roads usually (resulting in shitty lanes), and most areas see 60% to 70% of their land tied up in (mostly empty) parking, which is a disaster for every mode of transport.