Search results for "Passenger car equivalent"

Editorial: Calculation of Passenger Car Equivalents at Roundabouts

2021

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 performan…

Calibrating a microscopic traffic simulation model for roundabouts using genetic algorithms

2018

The paper introduces a methodological approach based on genetic algorithms to calibrate microscopic traffic simulation models. The specific objective is to test an automated procedure utilizing genetic algorithms for assigning the most appropriate values to driver and vehicle parameters in AIMSUN. The genetic algorithm tool in MATLAB® and AIMSUN micro-simulation software were used. A subroutine in Python implemented the automatic interaction of AIMSUN with MATLAB®. Focus was made on two roundabouts selected as case studies. Empirical capacity functions based on summary random-effects estimates of critical headway and follow up headway derived from meta-analysis were used as reference for ca…

Passenger Car Equivalent for Heavy Vehicles Crossing Turbo-roundabouts

2016

Abstract Turbo-roundabouts represent an innovative scheme of modern roundabouts which provides a spiraling traffic flow and requires drivers to choose their direction before entering the intersection, since raised lane separators mark the lanes on the ring. The configuration of the turbo-roundabout makes that patterns of conflict at entries with one and two conflicting traffic streams can coexist. This paper presents research efforts aimed at measuring quantitatively the effect of heavy vehicles on operational conditions of a turbo-roundabout. The study starts from the initial belief that the greatest constraints to the vehicular trajectories imposed by the turbo-roundabout necessarily impl…

Application of a genetic algorithm in calibration of traffic microsimulation models

2017

This chapter describes the genetic algorithm-based calibration procedure for a microscopic traffic simulation model focusing on freeways and modern roundabouts. For both case studies, the genetic algorithm tool in MATLAB® was applied in order to reach the convergence between the outputs from Aimsun microscopic simulator and the observed data. The automatic interaction with Aimsun software was implemented through an original external Python script. Results showed that the genetic algorithm-based calibration procedure gave a better match to the observed data than simple manual calibration and the efficiency of the calibration efforts resulted significantly improved. At last, the calbrated mod…

Passenger Car Equivalents for Heavy Vehicles at Roundabouts. a Synthesis Review

2019

Passenger Car Equivalents (PCEs in the following) are used to transform a mixed fleet of vehicles into a fleet of equivalent passenger cars and to analyze capacity and level-of-service of roads and intersections. Most roundabouts guidelines propose constant values for PCEs but a single PCE value can result improper under heterogeneous traffic conditions. PCEs should be vary with traffic and road conditions and consequently PCEs applied to undersaturated traffic conditions can overestimate the heavy vehicle effect or be not sensitive to the traffic level or characteristics of heavy vehicles. Compared to other at-grade intersections, the interaction between the operational performances of the…

Estimation of Passenger Car Equivalents for Two-Lane and Turbo Roundabouts Using AIMSUN

2020

The paper addresses issues related to Passenger Car Equivalents (PCEs) at roundabouts. Compared to other road units, the curvilinear elements of roundabout geometric design may impose greater constraints on vehicular trajectories and have a significant effect on the swept envelope of heavy vehicles. Specifically, the aim of the paper is to present the methodological approach which used traffic microsimulation to estimate PCEs. Focus is made on a case study which considered the conversion of a two-lane roundabout into a basic turbo roundabout with comparable size. Empirical capacity functions for both roundabouts were derived as target values to which simulated capacities by lane were compar…

Microsimulation-based passenger car equivalents for heavy vehicles driving turbo-roundabouts

2016

Due to its geometric design, turbo-roundabouts impose greatest constraints to the vehicular trajectories; by consequence, one can expect a more unfavourable impact of heavy vehicles on the traffic conditions than on other types of roundabouts. The present paper addresses the question of how to estimate Passenger Car Equivalents (PCEs) for heavy vehicles driving turbo-roundabouts. The microsimulation approach used revealed as a useful tool for evaluating the variation of quality of traffic in presence of mixed fleets (different percentages of heavy vehicles). Based on the output of multiple runs of several scenarios simulation, capacity functions for each entry lane of the turbo-roundabout w…

Estimation of Passenger Car Equivalents for single-lane roundabouts using a microsimulation-based procedure

2017

Calibration of microscopic traffic simulation models for single-lane roundabouts.Use of a meta-analytical estimation of critical and follow up headways.Use of a genetic algorithm-based procedure.Calculation of passenger car equivalents for single-lane roundabouts. Passenger car equivalents for heavy vehicles are required to carry out capacity calculations and perform operational analysis of any road entity (roadway segments or intersections). At single-lane roundabouts, the constraints to the vehicular trajectories imposed by the curvilinear geometric design and the driver's gap acceptance behaviour are expected to produce an impact of the heavy vehicles on the quality of traffic flow diffe…

Calibration of microscopic traffic simulation models for evaluating operation and safety performance at roundabouts

Developing Passenger Car Equivalents for Freeways by Microsimulation

2015

Abstract In this paper a method of estimation of the passenger car equivalents for heavy vehicles on freeway is described. The variation in traffic quality was evaluated basing on a traffic demand characterized by different percentages of heavy vehicles. Aimsun micro-simulator was used to isolate traffic conditions difficult to capture on field, to replicate them to have a number of data as much as possible numerous, and to quantify the fundamental variables of traffic flow, namely the speed, flow, density, for a test freeway segment. Model calibration was accomplished by using traffic data collected at observation sections on the A22 Brenner Freeway, Italy. In order to check to what extent…