First- and second-order phase transitions from free flow to synchronized flow

In this paper, we study the phase transition from free flow to synchronized flow. We carry out the simulations under the speed limit condition with a car-following model, the “full velocity difference model.” We find that the transition is second-order if the speed limit region is long and first-order if the speed limit region is short. This implies that the type of the transition depends on the type of the inhomogeneity.