Standing waves and the influence of speed limits

Traffic dependent speed limits have improved the security of highway traffic considerably. However, on highway sections controlled by variable speed limits large oscillations in speed can still be observed. On the basis of traffic data and a macroscopic traffic model, the influence of decentrally controlled speed limits on the states of highway traffic is analyzed. It is shown that local control of speed limits - which is typically applied - can lead to standing waves in speed. The anticipative control law proposed is able to prevent standing waves and can even damp out stop-and-go waves, such that a homogeneous traffic flow is gained.