A Tragedy of Autonomy. self-driving cars and urban congestion externalities

Much recent work on autonomous vehicles has focused on the ability of autonomous vehicles to form platoons, decreasing average vehicle headways and thereby increasing road capacities. However, it has recently been noted that autonomous vehicles could also effectively reduce passenger throughput despite the benefits of platooning due to a variety of effects, including the presence of unoccupied vehicles and the fact that increased road capacities can inadvertently lead to increases in aggregate congestion through various selfish routing paradoxes. This paper poses a model of urban traffic congestion in which occupants may choose to exit their vehicles at a workplace and then send the vehicle on to park itself-thus leading to an increased presence of unoccupied vehicles in urban centers. We show how this sets the stage for a tragedy of the commons, as it has the potential to amplify the already-present congestion externalities and how this can lead to increased aggregate congestion for a wide range of parameter values.