摘要：AbstractIn Highway Capacity Manual (HCM) 2010, various factors were considered to adjust the base saturation flow rate for capacity analysis of signalized intersections. However, impacts of short lane were only addressed by the adjustment for lane utilization based on deterministic analysis. Such analysis does not consider potential queue overflow and blockage resulted from short lane. This paper presented a theoretical model for estimating lane group capacity at signalized intersections with consideration of upstream short lane effects based on probability theory. Three scenarios of signal phase sequences were taken into account, reflecting the relationship between movement that may cause blockage and movement that may be blocked. The proposed model was validated by VISSIM simulation. Results of extensive analysis showed that the upstream short lane may have a substantial impact on capacity: the capacity is positively correlated with effective green time length and negatively correlated with short lane length. Among the three scenarios of phase sequence plans, the worst one causing the largest decrease in lane group capacity is phase sequence case 2 (the movement that may cause blockage follows the movement that may be blocked). It is shown that there is an optimal cycle length to obtain maximum capacity when upstream short lane exists.
