Gap time and stochastic wave propagation

Congested traffic shows very complicated stochastic features such as irregular transition of flow-density relations and the growth/decay of perturbations. In this paper, gap time is identified as a primary random variable in congested traffic and the wave speed is determined according to the relative difference between gap time and driver´s reaction time. The growth or decay of perturbations are explained in accordance with the random transition of observation points in the fundamental diagram.