Waymo driverless cars are coming alive at night, honking at each other and waking residents around the San Francisco parking lot where they sit when not making trips. 

The driverless taxi company has rented a lot outside of an apartment building for the cars to idle in, but the vehicles appear to be honking at each other, as they are trained to do on the road when other cars get close to them. 

Waymo attributed the disruptive honking to a feature designed to avoid collisions.