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This study explored the use of queue clearance rate method for estimating passenger car equivalent (PCE) at signalized intersections. PCE was estimated based on the assumption that the rate at which a queue of vehicles clears the intersection is a function of its composition. Results of this method were compared with the results estimated by some popular techniques. A four-legged intersection was simulated in VISSIM software and different techniques were used to convert the traffic mix into a uniform one. Parameters of VISSIM were modified to closely reflect the traffic behaviour under heterogeneous traffic conditions. All approaches of the intersection were loaded to saturated conditions and accuracy of estimated PCEs were established by comparing converted flow (PCE/h) with the capacity of an all-car traffic stream. Method based on saturation flow delivered the best result, but its use was limited to traffic composed only of two types of vehicles. Results of regression and optimization techniques were almost similar and the converted flow was close to the capacity of all-car stream. However, accuracy of these methods strongly relied on the correct measurement of saturation flow. Queue clearance rate method did not require value of saturation flow and yielded good estimates of PCE throughout the simulation runs. The maximum difference between the converted flow and capacity estimated with all car situations was found to be less than 10% in all cases considered in this study.

The main objective of this paper, based upon the extensive empirical research of free flow in local conditions, is to quantify the unfavourable impact of the flow structure on the road capacity using PCE (Passenger Car Equivalent) values as a function of longitudinal grade. Based on literature reviews and empirical research, it has been proved that the PCE value for all vehicle classes is directly correlated with the road gradient. The PCE values in free flow conditions have been determined for the approved vehicle classes. Based on the measured values, models for determining the average PCE value depending on the upward grade on two-lane roads have been developed. Comparison of the developed models in conditions of free traffic flow with the Highway Capacity Manual (HCM) models has shown lower PCE values in this research. Models for the percentage of PCE values PCE15%, PCE50% and PCE85% have also been established.

In developing countries, one of the vital steps involved in analysing the capacity of any transportation facility is the estimation of passenger car equivalents (PCEs) for different types of vehicles to convert the heterogeneous traffic stream into an equivalent stream of passenger cars. This study proposes occupancy time method for the estimation of PCEs for different types of vehicles generally observed at unsignalized intersections in India. PCEs for vehicles executing different movements at unsignalized intersections have been estimated in this study and the dynamic nature of PCEs has also been explored. However, PCEs were found to be statistically similar across different movements and across intersections of different geometry. [ABSTRACT FROM AUTHOR]

Traffic in developing countries is often distinguished from others for its diversity in vehicular composition and passenger car equivalents (PCE) becomes essential in such conditions for expressing traffic volume in terms of equivalent number of passenger cars. The PCE estimation at two-way stop-controlled intersections in developing countries is further complicated by the lack of movement priority and lane discipline. The study introduces a method to find PCE factors based on the time taken by a queue of vehicles to completely clear the intersection and composition of the queue. The method is validated through simulations in VISSIM software and was then used to derive PCE factors for three intersections in India. Although the method is developed and tested to estimate PCE factors under highly heterogeneous traffic at priority junctions in India, it is quite general in nature and can be used in traffic conditions found in developed countries as well. [ABSTRACT FROM AUTHOR]

With increasing urbanization, improved transportation technology and an expanding economy, additional roads and highways are built, in an effort to balance roadway capacity and demand. Knowledge of capacity of a road is essential in planning, design and operation of roads. To ascertain estimates of roadway capacity, Passenger Car Equivalent (PCE) factors are vital as they provide mechanism through which vehicles are converted into reference vehicle (i.e. Car). The paper discusses the case of Karachi (A metropolitan city of Pakistan) traffic environment where degree of heterogeneity is significantly high, and based on the collected data set from 12 different urban arterials of Karachi; presents the estimation of PCE factors from four different existing methods. Obtained PCE factors are then compared with each other and with those which are currently used in different traffic studies of Karachi. Significant differences are found among the values of PCE factors from each method. [ABSTRACT FROM AUTHOR]

Truck lane restriction and differential speed limits for trucks and passenger cars are becoming more common policies to improve freeway operations and safety. The most recent edition of the Highway Capacity Manual (HCM) recognizes that the passenger car equivalent ( ET) values may differ with various traffic conditions, but does not explicitly address how ET values may be impacted by truck lane restrictions or differential speed limit policies. This study developed a flow-based methodology to determine ET for trucks under truck lane restriction policies and different levels of demand and traffic composition. A simulation model (VISSIM) was calibrated to reproduce ET in HCM on a level terrain freeway segment and then used to simulate various scenarios to capture the effect of demand flow rate, truck percentage, and compliance ratio to lane restriction, all under the enforcement of differential speed limit policy. The results showed that ET increases as the compliance ratio increases, regardless of the truck percentage and demand flow rate. For a given traffic flow rate, ET decreases as the truck percentage increases. Moreover, regardless of the compliance ratio to lane restriction and the truck percentage, ET increases with the demand flow rate. The statistical analysis revealed that the truck percentage has a significant effect on ET for most cases, except when the truck percentage exceeds 30%. The results also showed significant differences in ET for all demand flow rates at 95% confidence level. The study also developed linear regression models for each level of service to estimate the value of ET as a function of the truck percentage and compliance ratio. [ABSTRACT FROM AUTHOR]

This paper investigates the hypothesis that the effect of heavy vehicles on traffic is greater during congestion than during undersaturated conditions. A new approach was developed to quantify this effect by deriving passenger car equivalents (PCEs) using queue discharge flow (QDF) capacity as the equivalency criterion. This approach is based on the premise that QDF capacity observations can be expected to show minimal variation if traffic stream was uniform and consisted of passenger cars only. Two sites in Ontario, Canada were used for this research. The first is located at an entrance ramp merge area and the second at a long-term freeway reconstruction zone. Nonlinear programming was utilized to perform optimizations on a number of data sets at each site. Results strongly suggest that the research hypothesis is true and that the approach developed by this research is both plausible and feasible. The mean PCE factor at the first site was 2.36 versus 1.5 in the Highway Capacity Manual (HCM) 2000. At the second site, the mean PCE factors in the two directions of travel were 3.21 and 2.7 versus 2.0 in the HCM 2000. Results also showed that the PCE factor developed from the optimization runs behaves as a random variable that generally follows the normal distribution. Furthermore, the PCE factor was neither a function of weather conditions nor of roadside maintenance work. [Copyright &y& Elsevier]