Social dilemma in traffic with heterogeneous drivers

There is a “tragedy of the traffic” analogous to the “tragedy of the commons” that can be caused by overtaking. We analyze the effect of overtaking in a minimal model of vehicular traffic, the Nagel–Schreckenberg model, with two types of strategies: vehicles that overtake and vehicles that do not. We show that, under certain circumstances, overtaking is good because it maximize the flux of vehicles and minimizes the vehicle’s mean time spent on the road. However, when these conditions are not met, overtaking is harmful to all. More specifically, we found that a social dilemma emerges in the vicinity of the transition to the congested traffic if the probability of random deceleration is low, which can also happen in more realistic single-lane models. The essential mechanism creating the social dilemma is the abrupt deceleration when the overtaking vehicle returns to its lane. We analyze how the payoffs depend on the frequency of strategies in the population to conclude that the vehicles that overtake are defectors and the ones that do not are cooperators, analogous to the strategies in “tragedy of the commons” class of games.