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# We stopped dead on the highway, crawled for ten minutes, and there was nothing up there
- URL: https://www.thefrictionlog.com/07580/
- Published: 2026-10-20T15:14:29.000Z
- Updated: 2026-10-20T15:14:29.000Z
- Description: Filed: the 1950s · Patched · a longer gap and a steady speed
- Author: The Clerk
- Tags: Patched

*Brake lights for eleven miles, then it just opens up. No wreck. No cop. Not even a cone.* — Commuter, 2019

Researchers in Japan put 22 drivers on a 230-meter circle and told them to hold a steady 30 kilometers an hour, about 19 miles an hour. There was no wreck and no obstacle of any kind. Small slips in spacing grew anyway, several cars stopped, and a jam formed and rolled backward through the line. The cars went forward and the jam went back, which is why you never find what caused it. They published it in 2008\. Nobody did anything wrong, and it happened anyway. A calm driver helps the cars behind, but you only control yours. Nobody caused it. Everybody's in it.

**For now**: leave a bigger gap to the car ahead and keep rolling at a steady speed instead of speeding up to close every gap.

### The full file

The idea is older than the experiment. In 1955 two mathematicians, Lighthill and Whitham, published a paper on traffic flow on long crowded roads. More than seventy years later, the jams are still here.

Then somebody tried to calm one. In Arizona in 2017, a single car that mostly drove itself, with a person steering, joined about twenty human drivers on a circular track at roughly 15 miles an hour. The humans were told to keep up with the car ahead, and not why. The waves faded, in some runs vanished, and in one study the pack burned up to 40% less fuel. That was one ring, one lane, no merging. The lead researcher called the result "almost too good to be true."

Don't count on the cruise control in your own car to do it for you. In a 2019 road test of seven cars, each one slowed more than the car ahead of it, since it only sees the car in front.

In November 2022, researchers ran 100 cars with AI-adjusted cruise control on Interstate 24 near Nashville, five days of morning commutes. Berkeley's engineers said the early results suggest a small share of such cars can change how all the traffic behaves. Early, and one road. No source gives a date for when it reaches your car, and the researchers say they still have to find the automakers and the regulators. Machines are learning to stay calm. You're welcome to start sooner.

**Relates to** [No. 08510](https://www.thefrictionlog.com/08510/).