  As an example for the optimization of unstable flows, we present an
economics-based method for deciding the optimal rates at which vehicles are
allowed to enter a highway. It exploits the naturally occuring fluctuations of
traffic flow and is flexible enough to adapt in real time to the transient flow
characteristics of road traffic. Simulations based on realistic parameter
values show that this strategy is feasible for naturally occurring traffic, and
that even far from optimality, injection policies can improve traffic flow.
Moreover, the same method can be applied to the optimization of flows of gases
and granular media.
