Estimation of saturation flow for non-lane based mixed traffic streams

Abstract

Saturation flow estimation is a challenge in non-lane based mixed traffic streams due to the presence of mixed vehicle-types, each having different static and dynamic characteristics. Such a mix gives way to traffic behaviours like weak lane discipline, multiple-leader following, etc. Due to these behaviours, queue discharge flow during green time fluctuates, which makes it difficult to identify a prolonged steady period of queue discharge required to estimate saturation flow. The present study is based on the hypothesis that the Passenger Car Unit (PCU) can explain the fluctuations in discharge caused by mixed vehicle-types. Accordingly, this study proposes a new model to estimate saturation flow along with PCUs from field data. Mathematical properties of the model are studied before field applications. Field data collected from six different locations are used to estimate the saturation flow and PCUs. The results indicate that the model can capture complex interactions of various vehicle-types.

Keywords:

• Saturation flow
• passenger car units
• signalised intersections
• optimisation model
• non-lane based mixed traffic
• capacity estimation

Acknowledgments

The authors wish to acknowledge the Central Road Research Institute (CRRI) and the Indian Highway Capacity Manual team for providing the data required for the study.

Disclosure statement

No potential conflict of interest was reported by the author(s).