How ants are so much better at traffic than we are

traffic jam
© Repina Veleriya

Despite their endless commuting, ants don't have traffic jams, regardless of the width of their path.

One of the challenges of being part of a collective system is preventing traffic jams in crowded environments. From a human perspective, this can be seen everywhere from the sidewalks of New York City to the parking lot also known as the 405 freeway in Los Angeles.

And it's not just humans who would be well-served by a lack of traffic jams. "Efficient transportation is crucial for urban mobility, cell function and the survival of animal groups," write scientists from the Research Center on Animal Cognition (CNRS) and the University of Arizona.

Looking at traffic in animal groups, the team set their sights on ants, noting that "few studies have looked at how ants maintain such a smooth flow even as the number of ants on a path increases." They found that ant colonies are spared the maddening headache of being stuck in a jam; they move along smoothly, even in extremely dense traffic.

"Ants, despite their behavioral simplicity, have managed the tour de force of avoiding the formation of traffic jams at high density," write the authors.

To arrive at this conclusion, the team conducted 170 filmed experiments to observe ants commuting between their nest and a food source. The width of the path and the number of ants in each test (between 400 and 25,600) were taken into account in order to vary the density, explains CNRS.

What they learned was surprising.

ants on a bridge© Ants running on a bridge. (Credit: Emmanuel PERRIN/CRCA/CNRS Photothèque)

When the density of ant traffic increases, ant flows swell and then become steady, unlike human traffic which above a certain density, slows to zero flow and causes a jam.

"For pedestrians and car traffic, the flow of movement will slow down if occupancy levels reach over 40%. Whereas in ants, the flow of traffic showed no signs of declining even when bridge occupancy reached 80%," write the authors. "The experiments revealed that ants do this by adjusting their behavior to their circumstances." Adding:

They speed up at intermediate densities, avoid collisions at large densities, and avoid entering overcrowded trails.

ants and traffic graph© Comparing traffic as a function of density, in ants and humans. (Credit: Audrey Dussutour)

Alas, this may not be the teaching moment we all need. While we certainly have a tremendous amount to learn from the non-human animal world, ants have some advantages that give them a leg-up when it comes to traffic. They come naturally equipped with a fancy exoskeleton that makes them unafraid of collisions, allowing them to accelerate, unlike humans, who slow down. (On the highways we have fancy exoskeletons too – cars – but they are too precious and dangerous for collisions. Maybe we should start driving bumper cars?)

Additionally, unlike humans, ants avoid the "traffic jam trap" with a more fluid set of traffic rules, adapting their traffic behavior to suit local crowding. They have more of a controlled anarchy, one that might not work so well with humans and their road rage and other assorted traffic tendencies.

As the researchers conclude, "Our results point to strategies by which ant colonies solve the main challenge of transportation by self-regulating their behavior." OK, maybe there's a lesson here after all? #BeLikeAnts

The study, "Experimental investigation of ant traffic under crowded conditions," was published in eLife.

How ants are so much better at traffic than we are
Despite their endless commuting, ants don't have traffic jams, regardless of the width of their path.

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