Skip to Content
Streetsblog Los Angeles home
Streetsblog Los Angeles home
Log In

This one comes to Streetsblog via the Sightline Institute's Daily Score, a blog covering environmental issues in the Pacific Northwest.

Why do traffic jams materialize for no apparent reason? In an effort to answer that question, here's a surprisingly simple experiment cooked up in Japan by the University of Nagoya's "Mathematical Society of Traffic Flow:"

If you are the kind of transportation geek who finds this sort of thing fascinating then you'll also really love this web-based traffic simulator out of Germany. But "prepare to lose your afternoon," says Sightline's Brad Plumer:

A few years back I wasted hour after hour playing with the java settings, and watching "traffic" jams materialize and melt -- just like in real life. My favorite quirk: for one lane-narrowing scenario, I could make traffic flow along beautifully at 40 miles per hour, but seize up like glue at either 20 mph or 60 mph. Another fave (and very relevant to congestion pricing debates) was letting traffic flow along smoothly at, say 1,400 "cars" per hour, and then increasing traffic volumes to 1,500 -- and watching the traffic jam crystallize within moments.

Story originally filed by Aaron Naparstek

Stay in touch

Sign up for our free newsletter

More from Streetsblog Los Angeles

Metro 2026 World Cup Transit Plans Emerging

From June 13 to July 7, 2026, Los Angeles will host eight World Cup soccer matches, all at the SoFi Stadium in the city of Inglewood

May 9, 2025

Metro Names Bill Scott as Chief of Police

Chief Scott and Metro leadership emphasized that keeping Metro transit safe would require a multi-faceted approach that included the deployment of officers as well as collaboration with the community, ambassadors, and service providers. "Sometimes enforcement is the answer," Scott said. "Sometimes it's not."

May 7, 2025

Lyft’s Anti-Worker Anti-Transit Record Raises Red Flags For Metro Bike Share

Edwin Aviles and Kalayaan Mendoza urge Metro not to reward bad actors working to undermine workers’ rights and mass transit

See all posts