Stuck on the Streets of San Francisco in a Driverless Car

When it approached a construction zone marked off with orange cones and a giant yellow arrow, it smoothly navigated around it, waiting for another car to pass on the right before proceeding. It snaked around a truck illegally parked at a sharp angle against the curb. And it stopped more than once for pedestrians who seemed as though they were about to cross the street, although this often came with a jolt to the passengers in the back seat. It also had a habit of slowing in the middle of an empty block for no apparent reason. Maybe it saw something that I didn’t — again and again.
Then, on the way back to the restaurant, about five miles into our ride, we drove west on Geary Boulevard, hoping to take a left onto Van Ness Avenue, a main thoroughfare.
We were interested to see how the car would handle the intersection, one of the busier corners in the city — and one, it turned out, with serious foot traffic for close to 9:30 p.m. on a Tuesday. For much of the ride, the car seemed to take side streets rather than main roads, steering well clear of heavy traffic and unprotected left-hand turns. But, as we approached Van Ness, vehicles lined up both in front and behind us. Suddenly, the car called off its turn and pulled to the side of the street.
“A potential collision was detected,” the disembodied voice said.
Just before the car pulled over, Mr. Henry had rolled down his window halfway and perched his iPhone on the edge of the glass using a small tripod. The idea had been to get a better angle on what was happening in front of the car. After the ride, a Cruise spokesman said the move had spooked the car. One leg of the tripod had been on the outside of the glass.
The company said its cars pulled to the curb if an object was “protruding unsafely” from the vehicle, or if someone tried to climb out of the window. But this typically will not happen, the company said, if a passenger puts his hand a short distance outside the window and waves to a friend.
The cars are designed to pull over when things go wrong. In April, police officers stopped a Cruise car after noticing its headlights weren’t on, and the car seemed to pull away from the officers as they walked to its window. It was pulling to the curb — much as it does when it spots an iPhone on a tripod.