Practical speed-flow relationship model of highway traffic-flow

Aiming at the shortcoming in generally used speed-flow relationship model, the theoretical models of speed flow relationship for each highway class are established based upon a large number of collected traffic data. The speed flow relationship model structure under different traffic load conditions is reviewed by analyzing the traffic flow dissipation mechanism under peak hour over saturated traffic condition. A general speed-flow relationship model under any traffic load conditions is established through curve fitting of large number of observed data. The practical model parameters for each highway class under different design speed are also put forward. This model successfully solves the speed-forecasting problem of the traffic flow under peak hour over saturated condition.