Study on the Capacity of Left-Through Shared Lane with Permitted Left-Turn Phasing

The capacity of left-through shared lane (here in after referred to as "shared lane") with permitted left-turn phasing (hereinafter referred to as "permitted phasing") is studied in detail in this paper. First, the effect of left-turn movement on through movement in the shared lane is analyzed comprehensively. Based on probability theory and random service system theory, a quantitative model is developed to estimate the capacity of shared lane with permitted phasing, considering the length factor of left-turn vehicle waiting area. Based on this model, a volume warrant for left-turn vehicle waiting area is generated and a method of calculating the optimum length of such area is presented. This study complements the HCM method, highlights the important role of left-turn vehicle waiting area in improving the capacity of the shared lane, and provides a quantitative guideline for traffic design in practice.