  Stop-and-go waves are commonly observed in traffic and pedestrian flows. In
most traffic models they occur through a phase transition after fine tuning of
parameters when the model has unstable homogeneous solutions. Inertia effects
are believed to play an important role in this mechanism. Here, we present a
novel explanation for stop-and-go waves based on stochastic effects in the
absence of inertia. The introduction of specific coloured noises in a stable
microscopic first order model allows to describe realistic stop-and-go
behaviour without requiring instabilities or phase transitions. We apply the
approach to pedestrian single-file motion and compare simulation results to
real pedestrian trajectories. Plausible values for the model parameters are
discussed.
