Analysis of Lost Times at Signalized Intersections

When determining the capacity of a signalized intersection, knowledge of certain traffic parameters is necessary. The previous investigation conducted under this study dealt with an analysis of saturation flow values. The objective of this investigation was to determine appropriate values to use for lost times at signalized intersections. The lost times at the beginning and ending of the phases were analyzed, as well as lost times during the phase due to the interference of pedestrians, local buses, and opposing traffic for left turns. Factors affecting those lost time values were identified. The lost time values, along with the previously identified saturation flow values, permit the calculation of capacity at signalized intersections and may be used as input when using computer models to simulate and optimize signal systems. Base values of 1.40 and 1.67 were found for beginning and ending lost time, respectively. Formulas were given that considered the effect of several factors on beginning and ending lost times. Case studies illustrating the use of those formulas are given