The behavior of Waymo’s self-driving taxis has apparently shifted in recent weeks or months, based on safety data collected by the company, and it means the cars are doing certain things more like real people do behind the wheel.

We don’t know the full extent to which Waymos vehicles have changed their behaviors via software adaptations. But the Chronicle points to a couple of new and "assertive" things the robot cars have been doing, including getting to a rolling start at a crosswalk after a pedestrian has nearly cleared the roadway — the kind of impatient maneuver most human drivers do, even if it is technically against the rules.

A USF engineering professor, William Riggs, took the Chronicle on a ride-along to observe these changes in behavior, which he's apparently been carefully documenting. He refers to "minimum risk" and "tenatively evasive" maneuvers by the robots, and he's seeing "a lot more anticipation and assertiveness from the vehicles" in general.

Waymo, the company, can confirm that this is happening. The company's director of product management David Margines says that engineers have been testing various behaviors in an effort to keep the Waymo experience from being too frustratingly granny-like, with the robots following every traffic safety law to the letter, in order that people get where they're going a bit quicker.

And, at least according to Margines and Waymo's data — which we have not personally seen — adding in some of these more human behaviors has made the cars, paradoxically, safer.

"Being an assertive driver means that you’re more predictable, that you blend into the environment, that you do things that you expect other humans on the road to do," Margines tells the Chronicle.

The company maintains that the robot cars remain far safer than those driven by humans, and they can execute quick evasive maneuvers when necessary that would be tough for most human drivers.

It remains to be seen, though, whether the robocars can figure out they're being punked when they have orange cones on their hoods.

Related: You Might Be Able to Buy and Own Your Own Self-Driving Waymo Someday

Photo by Hoseung Han