Research ArticleCalculation of Additional Lost Green Time at Closely Spaced Intersections

ABSTRACTAt closely spaced signalized intersections or interchanges, additional lost green time can occur at upstream intersections when there is a queue spillback. For an accurate estimation of capacities and delays at closely spaced intersections, it is necessary to account such additional lost time. The Highway Capacity Manual (HCM) 2010 provides a model for the estimation of the additional lost time due to the presence of a downstream queue. However, case studies indicate that the HCM model does not provide a very accurate estimation when the distance to the downstream queue is short. In this paper, a new model is developed for the estimation of additional lost time considering queue discharge patterns and traffic flow patterns. Simulation results show that the proposed model provides a more accurate estimation of additional lost time compared with the HCM model when the distance to the downstream queue is limited.