Multi-lane Traffic Flow Model: Speed Versus Density Difference as Lane Change Incentive and Effect of Lateral Flow Transfer on Traffic Flow Variables

For better and more efficient motorway traffic control strategies on a lane level, accurate modelling and prediction of traffic conditions is essential. Existing real-time traffic state estimation methods aggregate traffic across lanes. Hence, there is a need for lane-specific traffic flow models. The majority of the existing macroscopic lane-level traffic flow models use speed difference among lanes to explain lane change decisions. One of the major disadvantages of using speed difference as motivation for lane changing is the different speeds at which the lanes on a motorway operate. These models which are usually extensions of the Cell Transmission Model (CTM) also suffer in the manner in which lateral flow is transferred among cells in different lanes. In order to overcome these limitations, a model is proposed using density difference as an incentive to compute lane change rates rather than speed. A two-step transfer of lateral flow among cell segments is also considered where the lateral demand of a cell is dependent upon the receiving capacity of the adjacent and downstream cells in the target lane. The advantages of the presented approach is shown by comparing the proposed model with a conventional model. It was observed that the proposed model performed better in terms estimating densities across lanes. The proposed model is a step in the development of more accurate lane-specific traffic flow models.