Partial Elliptical Two-Regime Speed-Flow Traffic Model Based on the Highway Capacity Manual

There have been several attempts to describe traffic flow behaviour by modelling the relationship between the main variables describing traffic such as speed, flow and density. Some of these models are based on simplistic assumptions and therefore, they are far from being accurate in representing the whole range of traffic conditions (e.g. from free flowing to congested situations). This paper describes a speed-flow traffic model based on a tworegime linear speed-density relationship. The proposed model gives a mathematical representation for the likely speed-flow relationship based on published data from the Highway Capacity Manual. The model is robust and simple to use in describing this relationship for different traffic and roadway conditions. It can be applied in modelling traffic behaviour and used in estimating delays when dealing with stable as well as unstable traffic flow conditions ranging from free-flow to stationary queues. The model is also recommended for use in text books when describing speed-flow-density relationships.