Passenger Car Equivalent (PCE) of Regular Buses at Signalized Intersections under Saturated and Over-saturated Flow Regimes

Document Type : Research Paper

Authors

1 کارشناس ارشد

2 Assistant Professor at Shahrood University of Technology

3 Faculty of Civil Engineering, Shahrood University of Technology

4 Department of Civil Engineering, Shahrood University of Technology

Abstract

Passenger Car Equivalent (PCE) is a metric applied to represent the impact of different classes of vehicles on mixed flows by expressing it as the number of equivalent passenger vehicles.  The review of previous studies on PCE for signalized intersections showed that PCE was not determined by flow regime and the control delay, which is an essential indicator of performance of signalized intersections, was not employed to estimate PCE. Moreover, constant values has been considered for PCE and impacts of related variables on PCE has not been studied so far. The purpose of this study is to determine PCE of buses crossing signalized intersections for under-saturated, over-saturated, and near-saturated regimes using control delay and investigate the influential factors affecting PCE. Five intersections in Mashhad were studied and the methodology of Highway Capacity Manual (HCM2016) was used to compute control delay. The results show that in saturated regime, due to the instability of the flow, PCE has the highest value and in the under-saturated regime, due to the freedom of operation of passenger cars and their avoidance of being placed behind the buses, the amount of PCE is slightly greater than 1 and buses are nearly comparable to passenger cars. PCE was calculated for different traffic volume scenarios, percentages of buses, and green split and three linear models were estimated for each of the aforementioned regimes. The coefficients of determination of these models (R2) are very good and above 0.85. Traffic volume and green split are respectively the most influential variables.

Keywords


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