A Friday night incident saw a self-driving Waymo pop into the wrong lane for a couple blocks, but it may have had good reason to do so, because it was being swarmed by electric unicycle riders.

There was apparently some sort of a mini-Critical Mass for electric unicycles on Mission Street Friday night in the South of Market area. Now obviously, when you add a self-driving Waymo robotaxi into a Critical Mass-like situation, things are not likely to go well for the Waymo. And the Chronicle reports that the Waymo drove in the wrong lane of traffic for about two blocks, though honestly, this may have been a sound move for the robotaxi, as the unicycle riders seemed to be swarming and hoping to confuse the vehicle.

There have been two videos of the incident posted to Reddit, submitted for your approval below.

Just people having a fun time
byu/blazelord69 insanfrancisco

The Chronicle describes this as being around 9:30 Friday night, on the stretch of Mission Street around First and Second streets. The Waymo makes a perfectly legal left turn onto Mission Street, though the lane turns out to be full of electric unicycle-riding characters who are riding in the eastbound lane. So the Waymo drives east, but in the furthest-right westbound lane, as the unicycle riders shout “Waymo! That’s the wrong way!”

One of the unicyclists starts to circle the Waymo, which ends up giving the Waymo the space it needs to right itself back into the correct lane. This is all seen in another video below, which has some profanity, but is also kind of funny.

Waymo going down the street the wrong way
byu/okgusto inSelfDrivingCars

According to the Chronicle, there was a passenger inside the Waymo at the time of the incident. So that person had to be pretty freaked out, and likely relieved that the unicyclists didn’t set the car on fire or anything like that.

Waymo provided a statement to the Chronicle which said that the vehicle “detected that there may be a risk of a person within that crowd who had fallen down, and decided to carefully initiate a passing maneuver when the opposing lane was clear to move around what could be an obstacle and a safety concern.”

“After starting that maneuver, out of an abundance of caution around these vulnerable road users, and to avoid getting too close or cutting them off, the Waymo remained in the oncoming lane for longer than necessary before returning to its original lane of travel,” the statement added. “The safety of all road users is a top priority for Waymo, and we look forward to learning from this unique event.”

Basically, the Waymo has the seemingly reasonable excuse that the unicyclists were driving into car traffic, and seemingly trying to goad the vehicle into doing something wrong. And the vehicle did navigate the situation in a pretty safe manner. But it was able to do so because the road was not terribly busy, and there were traffic gaps and ways to avoid oncoming traffic. This may not always be the case in future chaotic situations, and this being San Francisco, prankster behavior is just something the robots are going to have to learn to exist with.

Related: Confused Waymo Cars Block 101 On-Ramp In Potrero Hill, Then Go Down Closed Road [SFist]

Image: blazelord69 via Reddit