Roundabouts trapped Clark Griswold in the movie "National Lampoon's Vacation," and now they've trapped a Waymo robot taxi. A video has been circulating on social media recently, showing a Waymo self-driving taxi going around and around the roundabout - as if stuck in a loop.

A Waymo spokesperson said there were no passengers in the vehicle in the video and said the company had addressed the issue through a software update to its fleet.The underlying logic of this strange behavior is unclear, and it's unclear how engineers ultimately corrected this particular situation.Over the past year, videos capturing the strange behavior of robotaxis have become increasingly common, especially in San Francisco, a city that can be considered the epicenter of self-driving car activity. For example, earlier this year, a woman started a livestream showing Waymo vehicles honking their horns all night long in a parking lot near her San Francisco apartment.