Passenger car equivalent for heavy vehicles crossing turbo-roundabouts

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 imply that the impact of heavy vehicles on the quality of traffic flow is more unfavorable than on other modern roundabouts. Microsimulation revealed as a useful tool when the variation of the traffic quality in turbo-roundabouts should be evaluated in presence of mixed fleets, each having different percentages of heavy vehicles; indeed, it allowed to isolate traffic conditions difficult to observe on field and replicate them to have a number of data as much as possible numerous. Entry capacity values for each entry lane of the turbo-roundabout were obtained by microsimulation, varying the percentage of heavy vehicles for entering flows. Nonlinear regression analysis of simulation data allowed to derive the behavioral parameters for heterogeneous populations of users and, ultimately, composed exclusively of heavy vehicles. The capacity functions thus obtained allowed us to determine how the passenger car equivalent (PCE) varies with the percentage of heavy vehicles and circulating flows for each entry lane of the turbo-roundabout. The results of this study indicate that there is a need to distinguish the impact of heavy vehicles when analyzing the capacity of a turbo-roundabout. When the traffic stream contains a significant number of heavy vehicles, a larger PCE effect would be expected. This effect should be accounted for in the estimation of the turbo-roundabout capacity. Lastly it should be emphasized that an important aspect of the research consists in having identified a methodology for assessing the impact of heavy vehicles on the quality of traffic flow, that can be applied to different patterns of intersection

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

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 compared. In order to estimate the PCEs a criterion of equivalence based on the amount of capacity used by cars and heavy vehicles is presented. AIMSUN allowed to simulate traffic conditions with different percentages of heavy vehicles at both roundabouts. Thus, variation of traffic conditions where mixed fleets operate was explored. A comparison was made between the PCEs estimated for each entry lane characterized by similar mechanism of entry maneuver. The results indicated there is a need to distinguish the impact of heavy vehicles when operational performance of a two-lane roundabout or a turbo-roundabout should be examined. Especially when circulating flows increase, a higher PCE value is expected than the value that the Highway Capacity Manual proposes for roundabouts

Integrating vehicle specific power methodology and microsimulation in estimating emissions on urban roundabouts

In this study pollutant emissions were estimated from VSP modal emission rates and the distribution of time spent in each VSP mode obtained from the speed profiles both gathered in the field and simulated in AIMSUN at a sample of urban roundabouts. The versatility of the micro-simulation model for a calibration aimed at improving accuracy of emissions estimates was tested in order to ensure that second-by-second trajectories experienced in the field by a test vehicle through the sampled roundabouts properly reflected the simulated speed profiles. The first results which the thesis will refer, confirmed the feasibility of the smart approach that integrates the use of field-observed and simulated data to estimate emissions at urban roundabouts. It is also revealed friendly in collecting information via smartphone and in the subsequent data analysis and provided suggestions for large-scale data collection through a digital community. Another goal of this research is to investigate about the environmental performance after a conversion of a traditional existing roundabout into a turbo-roundabout. This aspect has been considered a positive approach for a novel attitude in the performance evaluation of road networks to align the infrastructural design with the aim of sustainable and low-emission mobility. The main finding provided from this study is referred to the positive potential of a novel attitude in the conceptualization and performance evaluation of road units in order to align urban infrastructural projects with the worldwide shared long-term ambitions for a low-emission mobility

Assessing the Environmental Performances of Urban Roundabouts Using the VSP Methodology and AIMSUN

In line with globally shared environmental sustainability goals, the shift towards citizen-friendly mobility is changing the way people move through cities and road user behaviour. Building a sustainable road transport requires design knowledge to develop increasingly green road infrastructures and monitoring the environmental impacts from mobile crowdsourced data. In this view, the paper presents an empirically based methodology that integrates the vehicle-specific power (VSP) model and microscopic traffic simulation (AIMSUN) to estimate second-by-second vehicle emissions at urban roundabouts. The distributions of time spent in each VSP mode from instantaneous vehicle trajectory data gathered in the field via smartphone were the starting point of the analysis. The versatility of AIMSUN in calibrating the model parameters to better reflect the field-observed speed-time trajectories and to enhance the estimation accuracy was assessed. The conversion of an existing roundabout within the sample into a turbo counterpart was also made as an attempt to confirm the reproducibility of the proposed procedure. The results shed light on new opportunities in the environmental performance evaluation of road units when changes in design or operation should be considered within traffic management strategies and highlighted the potential of the smart approach in collecting big amounts of data through digital communities

The impact of vehicle movement on exploitation parameters of roads and runways: a short review of the special issue

"The impact of vehicle movement on exploitation parameters of roads and runways: a short review of the special issue" Transport, 31(2), p. 127-13

A Methodological Framework to Assess Road Infrastructure Safety and Performance Efficiency in the Transition toward Cooperative Driving

There is increasing interest in connected and automated vehicles (CAVs), since their implementation will transform the nature of transportation and promote social and economic change. Transition toward cooperative driving still requires the understanding of some key questions to assess the performances of CAVs and human-driven vehicles on roundabouts and to properly balance road safety and traffic efficiency requirements. In this view, this paper proposes a simulation-based methodological framework aiming to assess the presence of increasing proportions of CAVs on roundabouts operating at a high-capacity utilization level. A roundabout was identified in Palermo City, Italy, and built in Aimsun (version 20) to describe the stepwise methodology. The CAV-based curves of capacity by entry mechanism were developed and then used as target capacities. To calibrate the model parameters, the capacity curves were compared with the capacity data simulated by Aimsun. The impact on the safety and performance efficiency of a lane dedicated to CAVs was also examined using surrogate measures of safety. The paper ends with highlighting a general improvement with CAVs on roundabouts, and with providing some insights to assess the advantages of the automated and connected driving technologies in transitioning to smarter mobilit

Revisión del estado del arte (no sistemática) sobre el uso de algoritmos genéticos en la calibración de modelos de micro simulación vehicular

Este trabajo propone una revisión del estado del arte entre 2011 hasta la actualidad (2022), sobre el uso de Algoritmos Genéticos (AG) en la calibración de modelos de micro simulación vehicular. La calibración no es más que el proceso de optimización de modelos bajo la comparación de parámetros observados y reales. Se seleccionó a los AG debido a su gran robustez y capacidad de trabajo con grandes cantidades de datos. Se seleccionaron un total de 19 artículos de fuentes de investigación reconocidas como: IEEE Xplore, ScienceDirect, Springer Link y Scopus, respetando todos los criterios de selección y filtrado para únicamente trabajar con aquellos que aporten una actualización adecuada del tema. Los resultados muestran que gracias a la actualización de este tema se pudo constatar que el uso de los AG en la calibración de modelos de micro simulación vehicular tiene el potencial para mejorar y acelerar el proceso de calibración, lo cual ayudara a investigaciones y futuras publicaciones.This paper proposes a state-of-the-art review from 2011 to the present (2022) on the use of genetic algorithms (GA) to calibrate vehicle microsimulation models. Calibration is nothing more than the optimization process of models under comparing experimental and real parameters. Genetic algorithms (GA) were selected because of their excellent robustness and ability to work with large amounts of data. A total of 19 articles were selected from recognized research sources such as IEE Xplore, ScienceDirect, Springer Link, and Scopus, respecting all the selection and filtering criteria to work only with those that provide an adequate update of the topic. The results show that thanks to the update on this topic, it was possible to verify that the use of GA (Genetic Algorithms) in the calibration of vehicle microsimulation models can improve and accelerate the calibration process, which will help future research and publications

Traffic fundamentals for A22 Brenner freeway by microsimulation models.

La tesi di dottorato ha avuto come tema lo studio e l’applicazione di un modello di micro-simulazione del traffico in ambito autostradale. Essa si compone di quattro capitoli, con ognuno dei quali si è voluto sintetizzare e descrivere il lavoro di studio e ricerca svolto durante il suddetto corso di Dottorato di Ricerca. L’obiettivo principale del presente lavoro di tesi è stato quello di mettere a punto una metodologia finalizzata all’ottenimento delle relazioni fondamentali di deflusso in ambito autostradale attraverso il software di microsimulazione del traffico Aimsun. Come risulta infatti noto dalla letteratura scientifica, le relazioni fondamentali del deflusso sono utilizzate nel campo dell’ingegneria stradale per determinare il livello di servizio di alcune infrastrutture, quali ad esempio tronchi autostradali, al fine di fornire un’informazione utile alla previsione delle diverse condizioni operative di deflusso che si possono registrare su di esse. Nello specifico, la prima parte del lavoro di tesi è stata incentrata sullo sviluppo di una metodologia di calibrazione basata sulle relazioni velocità-densità nel processo di calibrazione di un modello di microsimulazione, visto che le predette relazioni rappresentano il fenomeno del traffico in un ampio range di condizioni operative e ben sintetizzano tutte le informazioni che possono essere raccolte sul campo su due delle tre variabili chiave del deflusso. Il confronto tra i dati di campo e i dati simulati è stato inizialmente condotto usando l’analisi statistica come tecnica di pattern recognition. In particolare, un segmento autostradale in condizioni non congestionate è stato scelto come caso studio; a partire dai dati rilevati sull’autostrada A22 del Brennero, sono state sviluppate regressioni statistiche tra le variabili del traffico. Analoghe relazioni sono state ottenute usando il software di microsimulazione del traffico Aimsun, che ha permesso di riprodurre le condizioni di campo e di variare alcuni parametri, finché è stato ottenuto un buon adattamento tra i dati di campo e i dati simulati. Nella fase di calibrazione manuale del modello di traffico in Aimsun è stato però difficile valutare l’effetto della variazione contemporanea di più parametri sugli output del modello. Ciò ha limitato sicuramente la scelta dei parametri del modello sui quali intervenire durante il processo di calibrazione e di valutare la risposta dello stesso anche in condizioni di funzionamento dell’autostrada diverse da quelle già considerate (tratto instabile della curva di deflusso). Per superare questo problema, nella fase finale del lavoro di tesi, è stato definito un algoritmo genetico in grado di calibrare in modo automatico i parametri del modello di microsimulazione e restituire così un “ottimo” set di valori in grado di minimizzare gli scarti fra i valori simulati e quelli osservati nella realtà. Ciò ha consentito un notevole risparmio di tempo rispetto alla procedura di calibrazione manuale precedentemente applicata. Un altro obiettivo del presente lavoro è stato finalizzato alla stima dell’impatto dei mezzi pesanti sulla qualità della circolazione per l’autostrada A22 del Brennero attraverso i risultati ottenuti in microsimulazione mediante i quali è stato infatti possibile calcolare i coefficienti di equivalenza (Passenger Car Equivalents Factor (PCEs)) tra i mezzi pesanti e le autovetture.In this work of PhD Thesis a methodology to find fundamentals diagrams by microsimulations will be presented. As it is know from scientific literature, the fundamental diagram relates two of the three variables: average speed (v), flow (q) and density (k) to each other. If two of these variables are known, the third can be derived using the relation q = kv. Therefore, if only one variable is known, and the fundamental diagram is known, the traffic state can be determined. The fundamental relationship is largely used in road infrastructure engineering, e.g. in the level-of-service evaluation of basic freeway or multilane segments. The present work of PhD thesis starts by introducing the fundamental diagram using Edie’s definitions and the use of speed- density diagrams. Another objective will be to analyzed a method that include an automated technique based on genetic algorithm (GA) for automating the process of calibration of the parameters in order to reproduce the fundamentals diagrams of the A22 Brenner freeway. A further important objective will be to evaluate the impact of heavy vehicle on the quality of flow of the A22 Brenner freeway by calculating the Passenger Car Equivalents Factor (PCEs) between heavy vehicles and cars based on the results obtained in microsimulation. The calculation of PCE (Passenger Car Equivalents) will be done in general terms in order to compare the results with those published in the Highway Capacity Manual (HCM, 2010) resulting from experimental studies

Transport Systems: Safety Modeling, Visions and Strategies

This reprint includes papers describing the synthesis of current theory and practice of planning, design, operation, and safety of modern transport, with special focus on future visions and strategies of transport sustainability, which will be of interest to scientists dealing with transport problems and generally involved in traffic engineering as well as design, traffic networks, and maintenance engineers

Сравнение качества обслуживания при доставке саморазгружающихся контейнеров

[For the English abstract and full text of the article please see the attached PDF-File (English version follows Russian version)].ABSTRACT Containers offer cost-cutting opportunities in cargo transportation, loading/unloading operations, improving the efficiency of machinery and equipment utilization. This leads to continued growth in the volume of containerized cargo transportation; however, this growth is held back by the limited number of container terminals where containers are transferred to automotive transport that delivers them to the end receiver. To address this problem, the authors have developed a technology to deliver containers without the use of container terminals (cf.: World of Transport and Transportation, Vol. 14, 2016, Iss. 4). This article assesses the quality of transportation services provided by the old conventional technology in comparison with the suggested one that relies on the use of the self-unloading container. Keywords: automotive transport, transportable container, transportation technology, jack posts, container terminals, container yards, service quality assessment.Текст аннотации на англ. языке и полный текст статьи на англ. языке находится в прилагаемом файле ПДФ (англ. версия следует после русской версии).Использование контейнеров даёт возможность сократить затраты на транспортировку грузов, погрузо- разгрузочные работы, повысить эффективность использования техники и оборудования. Это приводит к непрерывному росту контейнерных перевозок, однако темпы их роста сдерживаются недостаточным количеством терминальных комплексов, без которых нельзя осуществить перегрузку контейнеров на автомобильный транспорт, доставляющий их конечному потребителю. Для решения этой проблемы авторами была предложена технология доставки контейнеров без использования терминальных комплексов (см.: Мир транспорта, 2016, № 4). В публикуемой статье даётся оценка качества транспортного обслуживания при прежней привычной технологии и предлагаемой с использованием саморазгружающегося контейнера