Search results for "Roundabout"
showing 10 items of 70 documents
Environmental Performance Assessment of Urban Roundabouts
2021
To meet continuous and sustainable improvement on road infrastrucutures, new technologies and smart devices are encouraging the development of a mobile crowdsensing system for collecting and monitoring data to be used in efficiency assessment. In this view, the paper proposes a methodological approach that employs in an integrated way vehicle trajectory data collected in the field, the Vehicle Specific Power methodology and a microscopic traffic simulation model for estimating emissions at urban roundabouts. For a first characterization of the emissive phenomenon reference was made to an existing two-lane roundabout in Palermo, Italy, where vehicle trajectory data were collected using a sma…
Understanding Safety-Related Issues for Pedestrians at Modern Roundabouts. Journal of Sustainable Development, 5(4):23-37
2012
This paper examines the safety-related issues for pedestrians at modern roundabouts. For this purpose findings of research studies documented in the scientific literature and best practices have been examined trying to focus on roundabout installations by a pedestrians safety perspective. Whereas one of the main reasons for which roundabouts are built is related to safety benefits, roundabout design features and implications in road casualties have been commented first to evaluate the influence of roundabouts on pedestrian safety and then to identify design elements that have such a high potential for traffic safety. At last, measures and treatments that can be taken in the roundabouts desi…
Estimation of Air Pollutant Emissions in “Turbo” and in Conventional Roundabouts
2013
The road pollutant emissions, above all in urban context, are correlated to many infrastructural parameters and to traffic intensity and typology. The research work on road junction geometry, carried out in European research centres, has recently allowed to design new road intersection types which are of undoubted interest, especially in terms of traffic functionality and safety, like the turbo roundabouts (in which right-turn manoeuvres do not conflict with the circulating flow). The main objective of this paper is to propose a model for the estimation the performances and the pollutant emissions into turbo roundabouts. A comparative analysis between conventional roundabout and turbo round…
ROAD SAFETY PERFORMANCES FROM MICRO-SIMULATION CONSIDERING AUTONOMOUS VEHICLES OPERATIONS
2019
Introduction of Autonomous Vehicles in road traffic will remove the impact of the human factor from the driver’s decision-making process, and will transform the criteria for road network design, road infrastructure administration, traffic modeling and assessment tools for road safety management. The paper presents a microsimulation-based approach for safety performance evaluation of roundabouts where different percentages of Autonomous Vehicles are mixed with Conventional Vehicles. The simulated vehicle trajectories exported from VISSIM were used as a basis to estimate traffic conflicts through the Surrogate Safety Assessment Model (SSAM) for a sample of European roundabouts. In order to be…
Turbo roundabouts:geometric design parameters and performance analysis
2012
A turbo roundabout is a particular type of roundabout where entering and circulating lanes are bounded by traffic signs and by non-mountable curbs. The physical separation between lanes, both at entries and on the ring, helps to prevent side collisions crossing the roundabout. The main advantages of turbo roundabouts are: i) reduction in the number of potential conflict points; ii) lower speed of vehicles passing through the intersection; iii) safety conditions at the intersection due to lower risk of side-by-side accidents. Also, in some cases the capacities of turbo roundabouts are higher than the capacities of conventional roundabouts. This paper presents an estimation of capacity, delay…
A grid of material and immaterial laboratories for supporting the sustainability of transportation: the RESET project in Sicily
2015
Transportation is a crucial sector, to be suitably approached in order of getting human activities in more environmentally sustainable paths. In fact, in developing, as well in less developing, countries people and freights mobility are responsible of important amount of pollutant emissions and are cause of significant levels of energy consumptions. In this paper, a Sicilian regional project is presented, aiming at establishing an interconnected grid of material and immaterial laboratories. These laboratories, that are devoted at inducing more virtuous behaviors in the transportation policies, are constituted by equipment and software tools, mainly located in the region’s universities, acti…
Genetic algorithm-based calibration of microscopic traffic simulation model for single-lane roundabouts
2017
A calibration procedure for microscopic simulation models based on a genetic algorithm is proposed. Focus is made on single-lane roundabouts for which many random factors such as gap- acceptance affect operations. A comparison is performed between the capacity functions based on a meta- analytic estimation of critical and follow up headways and simulation outputs of a roundabout built in Aimsun microscopic simulator. Aimsun parameters were optimized using the genetic algorithm tool in MATLAB® which automatically interacted with Aimsun through a Python interface. Results showed that applying the genetic algorithm in the calibration process of the microscopic simulation model, a good match to…
A comparative empirical assessment of roundabouts operations in rural areas: impacts on congestion-specific vehicle speed profiles, pollutant and noi…
2020
Increasing concern about global warming and air quality has meant an increasing use of energetic and environmental indicators in roundabout design. The main objective of this paper is to compare different rural roundabouts in terms of traffic performance, pollutant and noise emissions through an integrated empirical assessment. Field measurements were carried out with a light duty vehicle in single-lane (SL), compact two-lane (CTL) and multi-lane (ML) roundabouts using Portable Emission Measurements Systems, OBD scan tool and Sound Level Meter, to measure real-world exhaust emissions, engine activity and acoustic data, respectively. Road traffic scene at roundabouts were obtained from video…
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…
Reducing Air Pollutants through Road Innovative Intersections
2013
Road pollutant emissions are correlated mainly to infrastructural capacity and to traffic intensity and typology. With the aim to improve road intersections performances in the last years was designed many new geometric layouts, like turbo roundabouts and flower roundabouts. The main objective of this paper is carried out a comparative analysis between conventional and innovative roundabouts in terms of CO, CO2, NO and PM2,5 vehicular emissions, evaluated by means of COPERT Software which is developed as a European tool for the calculation of emissions from the road transport sector.