A new perspective for saturation flows at signalized intersections

Abstract

Saturation flow is one of the fundamental parameter that is used to define the level of service, to assign signal timings and other traffic operations. In the conventional approaches (Highway Capacity Manual, Canadian Capacity Guide etc.) base value is adjusted by the parameters that represent field and traffic conditions. Although the results obtained are acceptable, the adjustment parameters may not reflect the field conditions properly in many countries and does not represent any effects on driver behavior. This paper presents a new formula for saturation flow based on driver behavior and some vehicle characteristics. In this formula, mean length, headway and acceleration rates of vehicles, saturation speeds of intersection and mean reaction time of vehicles in a queue are considered. The formula is tested with field data and compared to the values obtained by the HCM, CCG (Canadian Capacity Guide) and the Akcelik approaches. Based on these comparisons, it is commented that estimation of the new formula is promising.