Robocars improve traffic even when most cars around them are driven by people

I think it's plausible. I believe a lot of traffic would disappear if people drove the same speed. I do a lot of highway driving and use cruise control, and I see lots of cars go faster, then slow down, then go faster, then slow down, etc, causing more lane changes and probably annoying other drivers. Lane changes takes up two spaces and causes others to slow down creating a domino effect.

Traffic is one of those things where if everyone else looked out for each other, waited their turn, let people merge, etc, then everyone would get to their destinations sooner.

My experience with Waymos is that I am much more cautious around them both out of curiosity, but also because if something does go wrong, I don’t know what signals I have to change their behavior (e.g. honking, polite gesturing, etc.). Once autonomous cars are more common, I wonder if people will relax back to relaxed/sloppy/aggressive patterns. Maybe most already people don’t notice.

As an aside, I left a baseball game a few months ago and was surrounded by six Waymos leaving downtown with the game traffic. How wild to see almost the same number of driverless cars as traditional cars. My kids are young enough that they won’t know any different, but from my mid-40s perspective it may as well have been the Jetsons.

"Optimize" traffic flow all you like it's not really relevant at all because it's not the dominant problem, cannot ever address the fixed spacial constraints of car and road network, and whatever gains are achieved will be instantly swamped by induced demand and the fixed road network.

There may be hypothetical efficiencies to be found in a closed network, but that is not real life. In real life people may choose to begin driving or stop driving at any time. We need to be aware of the impacts of people deciding to drive more.

In real life as soon as traffic improves and time spent in traffic decreases that is a pricing signal to the market, lowering the time price of choosing to drive instead of other alternatives, and encouraging people to switch to driving vs other alternatives. The amount of traffic will increase again until it reaches the fixed maximum throughput of the road network or the highest price people will pay in terms their time before seeking other alternatives.

This is the well studied phenomenon of induced demand. Previously of concern to engineers weighing whether to build a 10 lane vs 8 lane bridge, but also very applicable to this new technology.

When we consider that there is a significant amount of people that currently cannot drive that will now be able to drive with the introduction of self driving cars, such as children and the elderly, it's clear that the most likely outcome of prevalent self driving cars will be a significant increase in the amount of cars on the road. This induced demand for driving will necessarily make traffic remarkably worse regardless of whatever marginal optimizations may occur.

I feel 100x safer in a Waymo than an Uber in SF. That said I did have a Waymo lose its mind and take me to a random alley in Chinatown at 3am…that was fun.

It’s a theoretical result, not something happening with current self-driving cars.

“Our work is the first to demonstrate the feasibility of controlling mixed traffic via robot vehicles at real-world, complex intersections.”

I skimmed the article, but the only metric I saw mentioned was that "traffic jams were eliminated". What metrics do the hypothetical robocars improve?

I ask because time-to-destination is not the only metric I find myself caring about. I will often choose a much longer, scenic, route instead of the congested highway even though it adds 10 (estimated) minutes to my trip. But I'd rather be actively driving, moving through space and feeling like I'm making progress for an hour than sit in a barely moving queue for 50 minutes.

I can't seem to find the original source, but I read years ago that a surprisingly small percentage (I believe 4%) of drivers just leaving excess headway was sufficient to mitigate most congestion-causing traffic waves. It makes sense to have robots be the ones driving in that counter-intuitive fashion.

This is talking about purely hypothetical future robocars that don't exist today. Yes, great. Flying cars would improve traffic too.

Only when you ban pedestrians and cyclists. I.e. in a dystopia.