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Editorial: Calculation of Passenger Car Equivalents at Roundabouts


Editorial on the Research Topic: Calculation of Passenger Car Equivalents at Roundabouts About this Research Topic: Calculation of Passenger Car Equivalents (PCEs) for heavy vehicles represents the starting point for the operational analysis of road facilities and other traffic management applications. PCEs are used to consider the presence of heavy vehicles in the traffic stream and are expressed as multiples of the effect of an average passenger car. Moreover, the highly curvilinear nature of the roundabout design, both in urban and rural environment, has significant effects on the paths that heavy vehicles would travel; as a consequence, the interaction between the physical and performance characteristics of the heavy vehicles and the geometric features of roundabouts can produce higher impacts on traffic operations than other at-grade intersections. The PCEs at roundabouts can be affected by numerous and specific factors, which include geometric and traffic properties, and other factors (e.g. location and environment, driver behaviour), the effect of which can be significant under conditions of unlimited traffic with high saturation degrees of the traffic streams. Based on these considerations, this Research Topic aims to verify the effect of geometric and traffic-related determinants on the calculation of PCEs for heavy vehicles at modern (i.e. single-lane and multi-lane roundabouts) roundabouts and alternative types of roundabouts (i.e. turbo and flower roundabouts). Since only a few studies were based on field data or have calibrated PCEs for roundabouts, academics and practitioners during the last decade have been using microscopic traffic simulation to calculate the PCEs on roundabouts. Thus, many challenges and research themes are still open for modern and alternative roundabouts, including: how to determine the PCE of different types of vehicle that reflect the actual traffic conditions in presence of motorized and non-motorized vehicles, or how to evaluate the transferability of the Highway Capacity Manual (HCM) recommendations for heterogeneous traffic conditions to adequately explain the traffic complexities of a mixed-traffic state, or how to optimize the working parameters of microscopic traffic simulation models in view of PCEs calculations, or how to assess the likely changes to traffic flow characteristics that may result from the introduction of new technologies for vehicles and how to assess the effects on fleet composition and level of service determinations. This Research Topic welcomes contributions addressing all aspects of simulation of PCEs for modern and alternative roundabouts geared toward solving the above questions. As such, we solicit submissions of research papers dealing with themes that include, but are not limited to: • Prediction of entry lane capacity for roundabouts in heterogeneous traffic conditions and model calibration; • Estimation of capacity for roundabouts based on percentages of heavy vehicles in entering and circulating flows; • Prediction of the entry capacity based on the difference in driver’s gap acceptance behavior between cars and heavy vehicles; • Planning and designing of roundabouts under mixed-traffic flow conditions; • Case studies.