Lane Volume and Saturation Flow Rate for Multilane Intersection Approach

One factor that can reduce a lane's saturation flow to less than ideal conditions is when turning vehicles share the lane with through vehicles. The slow discharge rate of the turning vehicles reduces the lane's effective saturation flow rate in direct proportion to the percentage of turn vehicles in it. A model is described that predicts this percentage and the resulting saturation flow rate of the shared lane. Based on the results of this research, it is believed that the proposed model accurately predicts the lane volume for any approach to a signalized intersection and the uncontrolled approach to an unsignalized intersection. The model extends previous models by incorporating a sensitivity to both left- and right-turn movements and the probability of a lane change into a closed-form solution. Some field data are used to validate the proposed model.