Assessing the Environmental Performances of Urban Roundabouts Using the VSP Methodology and AIMSUN (original) (raw)
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Archives of Transport
Energy efficiency has a central role to play in achieving decarbonisation targets in the transport system by changing the demand for mobility (eg. by influencing on peoples behaviors) and improving the performance of the fleet. In recent years there has been an increase of use of private transport, partly due to the recent pandemic and the reduced choice of public transport. People's travel habits have changed in frequency and motivation due to the reduced number of seats on public transport, due to social distancing but also due to online education and teleworking. This increase of use private cars has led to an increase in environmental emissions as a result of the high proportion of vehicles with combustion engines in urban areas. The highest concentrations have been recorded at road intersections and in par-ticular at roundabout configurations where there is a higher number of stop-and-go's overall. The increasing im-portance of air pollution from vehicle traffic has sug...
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This paper reports on research that explored how multilane roundabouts located on urban corridors have affected traffic performance and pollutant emissions generated from vehicles. The research also compared the emissions of vehicles moving through the roundabouts as they used either the left or right entry lanes. The methodology can be generalized to measure the emissions of any multilane roundabout. The paper identified a representative speed profile for each speed trajectory type, no stop, one stop, and multiple stops, from field data collected at four multilane roundabouts in Aveiro, Portugal. The vehicle-specific power emissions methodology was employed to estimate the second-by-second emissions generated from a vehicle during different acceleration–deceleration cycles. Congestion-specific vehicle speed profiles for two-lane roundabout approaches were used to develop regression models to predict the percentage of vehicles that would experience different speed trajectory types i...
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Steady growth of traffic over the years has put environmental stress on urban centers in various forms particularly causing poor air quality. Urban air quality is generally poor at traffic intersections due to variations in idle timing and vehicles’ speeds as they approach and leave. Modern roundabouts can reduce the idle time of vehicles resulting in reduced air pollution. The primary objective and focus of this research was to study the impact of modern roundabouts on vehicular emissions as well as provision of level of service compared to signalized and unsignalized intersections. Twelve existing intersections were selected from the center of Bangkok, Thailand, with respect to traffic volumes, percentage of heavy vehicles, geometry of the intersection and vehicle speeds. Traffic operation of the intersections was videotaped and traffic data was extracted from the tapes. Analysis was conducted using 3.2 Version of Signalized and Unsignalized Intersection Design and Research Aid (S...
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Although largely diffused in Europe, modern roundabouts are scarcely diffused in Italy. Nevertheless, it is well known that the introduction of such roundabouts to replace congested crossings often leads to quite smooth-flowing traffic. On the other hand, the impact of roundabout on traffic emissions is scarcely presumed. In this paper we propose an evaluation, by means of traffic models and vehicle emission models, of the progresses achievable by switching from traffic lightcontrolled crossings to roundabouts. The improvement, in terms of air quality, is estimated in relation to the characteristics of traffic flow, road capacity and regulation. Significant variations have been quantified with dependence on these parameters. In the first step of our study, national regulations and technical literature about roundabouts have been analyzed to point out fundamental characteristics and the limits of their application. A simple model has been developed in order to automatically compute t...
International Journal of Automotive and Mechanical Engineering, 2020
Due to the increased emission of harmful exhaust components, in particular CO2 (carbon dioxide), CO (carbon monoxide), THC (total hydrocarbons), by motor vehicles, especially in the centres of urban agglomerations, it is necessary to create traffic simulation models that allow to estimate the emissions from road transport. One of the places where the largest accumulation of vehicles in cities occurs are intersections. This contributes to increasing the number of stops and repetitions of the acceleration and braking cycle, which has a direct impact on vehicle emissions. At the same time, roundabouts are intersections with specific traffic movement characteristics, therefore it is necessary to calibrate the simulation model beforehand. The aim of the study was to develop a methodology for modeling vehicle traffic at the roundabout and compare the combustion engines emissions resulting from vehicle movement on the example of the selected roundabout case studies. Vehicle traffic modelin...