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The paper presents a microsimulation approach for assessing the safety performance of turbo-roundabouts where Cooperative Autonomous Vehicles “CAVs” have been introduced into the traffic mix alongside conventional vehicles “CVs”. Based on the analysis of vehicle trajectories from VISSIM and subsequent analysis of traffic conflicts through the Surrogate Safety Assessment Model (SSAM), the research aims to evaluate the safety benefits of turbo-roundabouts where the lanes are physically separated by raised curbs, compared to roundabouts without such curbs. The paper will then describe the methodological path followed to build VISSIM models of turbo-roundabouts with and without raised curbs in order to calibrate the simulation models and estimate the potential conflicts when a higher percentage of CAVs are introduced into the traffic mix. A criterion has been also proposed for setting properly the principal SSAM filters. The results confirmed both higher safety levels for turbo-roundabouts equipped with raised lane dividers compared to turbo-roundabout solutions without curbs, and better safety conditions under the traffic mix of CVs and CAVs. Therefore, it follows that, in absence of crash data including CAVs, the surrogate measures of safety are the only approach in which the safety performance of any roundabout or road entity can be evaluated.
Tullio Giuffrè; Anna Granà; Salvatore Trubia. Safety Evaluation of Turbo-Roundabouts with and without Internal Traffic Separations Considering Autonomous Vehicles Operation. Sustainability 2021, 13, 8810 .
AMA StyleTullio Giuffrè, Anna Granà, Salvatore Trubia. Safety Evaluation of Turbo-Roundabouts with and without Internal Traffic Separations Considering Autonomous Vehicles Operation. Sustainability. 2021; 13 (16):8810.
Chicago/Turabian StyleTullio Giuffrè; Anna Granà; Salvatore Trubia. 2021. "Safety Evaluation of Turbo-Roundabouts with and without Internal Traffic Separations Considering Autonomous Vehicles Operation." Sustainability 13, no. 16: 8810.
The importance of being circular reflects one of the key concepts of the life-cycle thinking that promotes the sustainable production of goods and services. If it is true that the analysis of the product life-cycle is fundamental to optimize the use of resources and to plan for the future reduction of adverse effects on urban environment, it is also true that there are still several barriers covering conceptual and practical issues which hinder the building of shared approaches for the economic evaluation of infrastructure projects. The chapter presents a case study where the Life-Cycle Cost methodology is used to compare three alternative intersection projects based on their total life-cycle costs. The results confirmed the flexibility of the methodology—at urban level—also when environmental criteria should be integrated to conceptualize design solutions of intersections and to provide perspective on their performance to satisfy the major design needs starting from the planning stage.
Orazio Giuffrè; Anna Granà; Tullio Giuffrè; Francesco Acuto; Anthony Lo Pinto. Life-Cycle Costing Decision-Making Methodology and Urban Intersection Design: Modelling and Analysis for a Circular City. Inventive Computation and Information Technologies 2021, 59 -86.
AMA StyleOrazio Giuffrè, Anna Granà, Tullio Giuffrè, Francesco Acuto, Anthony Lo Pinto. Life-Cycle Costing Decision-Making Methodology and Urban Intersection Design: Modelling and Analysis for a Circular City. Inventive Computation and Information Technologies. 2021; ():59-86.
Chicago/Turabian StyleOrazio Giuffrè; Anna Granà; Tullio Giuffrè; Francesco Acuto; Anthony Lo Pinto. 2021. "Life-Cycle Costing Decision-Making Methodology and Urban Intersection Design: Modelling and Analysis for a Circular City." Inventive Computation and Information Technologies , no. : 59-86.
Increasing concern about global warming and air quality has meant an increasing use of energetic and environmental indicators in roundabout design. This research compares different suburban 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, On-Board Diagnostic scan tool and Sound Level Meter, to measure real-world exhaust emissions, engine activity and acoustic data, respectively. Afterwards, predictive discrete choice models that correlate the probability of occurrence of speed profiles (no stop, stop once and multiple stops) with roundabout operational parameters were developed. Although SL yielded the lowest carbon dioxide (CO2) per vehicle, a high equivalent continuous A-weighted sound level (LAeq) was returned because vehicles drove at moderate speeds in the approach and low conflicting traffic was identified when compared to the other layouts. CTL was the worst option in terms of both CO2 and nitrogen oxides (NOx). The proposed methodology can be used to quantify the performance of roundabout layouts in suburban areas by simply identifying their traffic volumes, noise level, pollutant emission and representative speed profiles. This can help researchers, traffic planners or practitioners to reduce congestion and emissions, and enhance road traffic management near urban areas.
P. Fernandes; R. Tomás; F. Acuto; A. Pascale; B. Bahmankhah; C. Guarnaccia; A. Granà; M.C. Coelho. Impacts of roundabouts in suburban areas on congestion-specific vehicle speed profiles, pollutant and noise emissions: An empirical analysis. Sustainable Cities and Society 2020, 62, 102386 .
AMA StyleP. Fernandes, R. Tomás, F. Acuto, A. Pascale, B. Bahmankhah, C. Guarnaccia, A. Granà, M.C. Coelho. Impacts of roundabouts in suburban areas on congestion-specific vehicle speed profiles, pollutant and noise emissions: An empirical analysis. Sustainable Cities and Society. 2020; 62 ():102386.
Chicago/Turabian StyleP. Fernandes; R. Tomás; F. Acuto; A. Pascale; B. Bahmankhah; C. Guarnaccia; A. Granà; M.C. Coelho. 2020. "Impacts of roundabouts in suburban areas on congestion-specific vehicle speed profiles, pollutant and noise emissions: An empirical analysis." Sustainable Cities and Society 62, no. : 102386.
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.
Anna Granà; Tullio Giuffrè; Elżbieta Macioszek; Francesco Acuto. Estimation of Passenger Car Equivalents for Two-Lane and Turbo Roundabouts Using AIMSUN. Frontiers in Built Environment 2020, 6, 1 .
AMA StyleAnna Granà, Tullio Giuffrè, Elżbieta Macioszek, Francesco Acuto. Estimation of Passenger Car Equivalents for Two-Lane and Turbo Roundabouts Using AIMSUN. Frontiers in Built Environment. 2020; 6 ():1.
Chicago/Turabian StyleAnna Granà; Tullio Giuffrè; Elżbieta Macioszek; Francesco Acuto. 2020. "Estimation of Passenger Car Equivalents for Two-Lane and Turbo Roundabouts Using AIMSUN." Frontiers in Built Environment 6, no. : 1.
The paper describes the pilot study conducted to assess the feasibility of the empirical approach utilizing vehicle trajectory data from a smartphone app and the Vehicle-Specific Power methodology to estimate pollutant emissions at urban roundabouts. The goal of this research phase is to acquire instantaneous speed data from a sample of six roundabouts located in the road network of the City of Palermo, Italy, and quantify emissions generated by the test vehicle through the examined roundabouts. For the case studies of roundabouts acceleration events in the circulating and exiting areas contributed to about 25% of the emissions for a given speed profile. More in general, the results from this research shed lights for further opportunities to examine infrastructural scenarios when decision makers require to assess changes in the design or operation of urban transportation systems.
Orazio Giuffrè; Anna Granà; Tullio Giuffrè; Francesco Acuto; Maria Luisa Tumminello. Estimating Pollutant Emissions Based on Speed Profiles at Urban Roundabouts: A Pilot Study. Advances in Intelligent Systems and Computing 2019, 184 -200.
AMA StyleOrazio Giuffrè, Anna Granà, Tullio Giuffrè, Francesco Acuto, Maria Luisa Tumminello. Estimating Pollutant Emissions Based on Speed Profiles at Urban Roundabouts: A Pilot Study. Advances in Intelligent Systems and Computing. 2019; ():184-200.
Chicago/Turabian StyleOrazio Giuffrè; Anna Granà; Tullio Giuffrè; Francesco Acuto; Maria Luisa Tumminello. 2019. "Estimating Pollutant Emissions Based on Speed Profiles at Urban Roundabouts: A Pilot Study." Advances in Intelligent Systems and Computing , no. : 184-200.
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 heavy vehicles and the geometric features at roundabouts can produce significant impacts on the heavy vehicle paths and traffic operations due to the curvilinear nature of the roundabout design. Literature presents various methods of estimation to obtain PCE values for heavy vehicles. The focus of this paper is to review statistical methods and traffic simulation studies based on microscopic approaches used to calculate PCEs for heavy vehicles driving roundabouts. Effects on capacity and estimates of PCEs based on models currently employed in roundabout analysis are also compared. The results obtained in this study aim at providing an overview of the existing knowledge concerning the estimation of PCEs at roundabouts and can represent a guideline for transportation engineers in planning, design and capacity analysis of roundabouts that operate under conditions of mixed traffic.
Orazio Giuffrè; Anna Granà; Tullio Giuffrè; Maria Luisa Tumminello; Francesco Acuto. Passenger Car Equivalents for Heavy Vehicles at Roundabouts. a Synthesis Review. Frontiers in Built Environment 2019, 5, 1 .
AMA StyleOrazio Giuffrè, Anna Granà, Tullio Giuffrè, Maria Luisa Tumminello, Francesco Acuto. Passenger Car Equivalents for Heavy Vehicles at Roundabouts. a Synthesis Review. Frontiers in Built Environment. 2019; 5 ():1.
Chicago/Turabian StyleOrazio Giuffrè; Anna Granà; Tullio Giuffrè; Maria Luisa Tumminello; Francesco Acuto. 2019. "Passenger Car Equivalents for Heavy Vehicles at Roundabouts. a Synthesis Review." Frontiers in Built Environment 5, no. : 1.
The paper presents a microsimulation-based approach for roundabout safety performance evaluation. Based on a sample of Slovenian roundabouts, the vehicle trajectories exported from AIMSUN and VISSIM were used to estimate traffic conflicts using the Surrogate Safety Assessment Model (SSAM). AIMSUN and VISSIM were calibrated for single-lane, double-lane and turbo roundabouts using the corresponding empirical capacity function which included critical and follow-up headways estimated through meta-analysis. Based on calibration of the microsimulation models, a crash prediction model from simulated peak hour conflicts for a sample of Slovenian roundabouts was developed. A generalized linear model framework was used to estimate the prediction model based on field collected crash data for 26 existing roundabouts across the country. Peak hour traffic distribution was simulated with AIMSUN, and peak hour conflicts were then estimated with the SSAM applying the filters identified by calibrating AIMSUN and VISSIM. The crash prediction model was based on the assumption that the crashes per year are a function of peak hour conflicts, the ratio of peak hour traffic volume to average daily traffic volume and the roundabout outer diameter. Goodness-of-fit criteria highlighted how well the model fitted the set of observations also better than the SSAM predictive model. The results highlighted that the safety assessment of any road unit may rely on surrogate safety measures, but it strongly depends on microscopic traffic simulation model used.
Orazio Giuffrè; Anna Granà; Maria Luisa Tumminello; Tullio Giuffrè; Salvatore Trubia; Antonino Sferlazza; Marko Rencelj. Evaluation of Roundabout Safety Performance through Surrogate Safety Measures from Microsimulation. Journal of Advanced Transportation 2018, 2018, 1 -14.
AMA StyleOrazio Giuffrè, Anna Granà, Maria Luisa Tumminello, Tullio Giuffrè, Salvatore Trubia, Antonino Sferlazza, Marko Rencelj. Evaluation of Roundabout Safety Performance through Surrogate Safety Measures from Microsimulation. Journal of Advanced Transportation. 2018; 2018 ():1-14.
Chicago/Turabian StyleOrazio Giuffrè; Anna Granà; Maria Luisa Tumminello; Tullio Giuffrè; Salvatore Trubia; Antonino Sferlazza; Marko Rencelj. 2018. "Evaluation of Roundabout Safety Performance through Surrogate Safety Measures from Microsimulation." Journal of Advanced Transportation 2018, no. : 1-14.
Orazio Giuffrè; Anna Granà; Maria Luisa Tumminello; Antonino Sferlazza. Calibrating a microscopic traffic simulation model for roundabouts using genetic algorithms. Journal of Intelligent & Fuzzy Systems 2018, 35, 1791 -1806.
AMA StyleOrazio Giuffrè, Anna Granà, Maria Luisa Tumminello, Antonino Sferlazza. Calibrating a microscopic traffic simulation model for roundabouts using genetic algorithms. Journal of Intelligent & Fuzzy Systems. 2018; 35 (2):1791-1806.
Chicago/Turabian StyleOrazio Giuffrè; Anna Granà; Maria Luisa Tumminello; Antonino Sferlazza. 2018. "Calibrating a microscopic traffic simulation model for roundabouts using genetic algorithms." Journal of Intelligent & Fuzzy Systems 35, no. 2: 1791-1806.
This paper addresses issues on road safety analysis through microscopic traffic simulation models. The Surrogate Safety Assessment Model (SSAM) was applied to read vehicle trajectory files generated by two micro-simulators and then calculate surrogate measures of safety. Since safety assessment of any road entity can provide different results based on the micro-simulator which is used, the main objective of this research was to estimate the safety performance of three roundabout layouts and compare the conflict events simulated by AIMSUN and VISSIM. The two micro-simulators were used to build the calibrated models of the roundabouts, each fitting the corresponding empirical capacity function. The results provided insights on how to set the SSAM filters in order to have a comparable frequency of conflicts by simulation and examine conditions under which a safety analysis could be independent of the software used.
Orazio Giuffrè; Anna Granà; Maria Luisa Tumminello; Tullio Giuffrè; Salvatore Trubia. Surrogate Measures of Safety at Roundabouts in AIMSUN and VISSIM Environment. Roundabouts as Safe and Modern Solutions in Transport Networks and Systems 2018, 53 -64.
AMA StyleOrazio Giuffrè, Anna Granà, Maria Luisa Tumminello, Tullio Giuffrè, Salvatore Trubia. Surrogate Measures of Safety at Roundabouts in AIMSUN and VISSIM Environment. Roundabouts as Safe and Modern Solutions in Transport Networks and Systems. 2018; ():53-64.
Chicago/Turabian StyleOrazio Giuffrè; Anna Granà; Maria Luisa Tumminello; Tullio Giuffrè; Salvatore Trubia. 2018. "Surrogate Measures of Safety at Roundabouts in AIMSUN and VISSIM Environment." Roundabouts as Safe and Modern Solutions in Transport Networks and Systems , no. : 53-64.
Orazio Giuffrè; Anna Granà; Maria Luisa Tumminello; Antonino Sferlazza. Capacity-based calculation of passenger car equivalents using traffic simulation at double-lane roundabouts. Simulation Modelling Practice and Theory 2018, 81, 11 -30.
AMA StyleOrazio Giuffrè, Anna Granà, Maria Luisa Tumminello, Antonino Sferlazza. Capacity-based calculation of passenger car equivalents using traffic simulation at double-lane roundabouts. Simulation Modelling Practice and Theory. 2018; 81 ():11-30.
Chicago/Turabian StyleOrazio Giuffrè; Anna Granà; Maria Luisa Tumminello; Antonino Sferlazza. 2018. "Capacity-based calculation of passenger car equivalents using traffic simulation at double-lane roundabouts." Simulation Modelling Practice and Theory 81, no. : 11-30.
Orazio Giuffrè; Anna Granà; Maria Luisa Tumminello; Antonino Sferlazza. Estimation of Passenger Car Equivalents for single-lane roundabouts using a microsimulation-based procedure. Expert Systems with Applications 2017, 79, 333 -347.
AMA StyleOrazio Giuffrè, Anna Granà, Maria Luisa Tumminello, Antonino Sferlazza. Estimation of Passenger Car Equivalents for single-lane roundabouts using a microsimulation-based procedure. Expert Systems with Applications. 2017; 79 ():333-347.
Chicago/Turabian StyleOrazio Giuffrè; Anna Granà; Maria Luisa Tumminello; Antonino Sferlazza. 2017. "Estimation of Passenger Car Equivalents for single-lane roundabouts using a microsimulation-based procedure." Expert Systems with Applications 79, no. : 333-347.
In gap-acceptance theory the critical and the follow-up headways have a significant role in determining roundabout entry capacities which in turn depend on circulating flow rates under a specified arrival headway distribution. Calculation considers single mean values of the gap-acceptance parameters, neglecting the inherent variations in these random variables and providing a single value of entry capacity. The purpose of this paper is to derive the entry capacity distribution which accounts for the variations of the contributing (random) variables and suggest how to consider this issue in the operational analysis of the roundabouts. We performed a Monte Carlo simulation to get the distribution of entry capacity and found Crystal Ball software effective for performing the random sampling from the probability density functions of each contributing parameter. A steady-state model of capacity was used for performing many runs; in each run, the values of each contributing parameter were randomly drawn from the corresponding distributions. The paper presents the first simulations and the entry capacity distributions at roundabouts, once the probability distributions of the headways were assumed. The results of the analysis were expressed probabilistically, meaning that the probability distributions of capacity rather than the simple point estimates were obtained. Comparing the capacity values based on a meta-analytic estimation of critical and follow-up headways and the capacity functions based on the probability distributions of the model parameters, more insights in developing an appropriate approach to capacity estimation at roundabouts can be gained.
Orazio Giuffrè; Anna Granà; Maria Luisa Tumminello. Exploring the uncertainty in capacity estimation at roundabouts. European Transport Research Review 2017, 9, 18 .
AMA StyleOrazio Giuffrè, Anna Granà, Maria Luisa Tumminello. Exploring the uncertainty in capacity estimation at roundabouts. European Transport Research Review. 2017; 9 (2):18.
Chicago/Turabian StyleOrazio Giuffrè; Anna Granà; Maria Luisa Tumminello. 2017. "Exploring the uncertainty in capacity estimation at roundabouts." European Transport Research Review 9, no. 2: 18.
Several studies and researches have shown that modern roundabouts are safe and effective as engineering countermeasures for traffic calming, and they are now widely used worldwide. The increasing use of roundabouts and, more recently, turbo and flower roundabouts, has induced a great variety of experiences in the field of intersection design, traffic safety and capacity modelling. As for unsignalized intersections which represent the starting point to extend knowledge about the operational analysis to roundabouts, the general situation in capacity estimation is still characterized by the discussion between gap acceptance models and empirical regression models. However, capacity modelling must contain both the analytical construction and then solution of the model, and the implementation of driver behavior. Thus, issues on a realistic modelling of driver behavior by the parameters that are included into the models are always of interest for practioners and analysts in transportation and road infrastructure engineering. Based on these considerations, this paper presents a literature review about the key methodological issues in the operational analysis of modern roundabouts. Focus is made on the aspects associated with the gap acceptance behavior, the derivation of the analytical-based models and the calculation of parameters included into the capacity equations, as well as steady state and non-steady state conditions and uncertainty in entry capacity estimation. At last, insights on future developments of the research in this field of investigation will be also outlined.
Orazio Giuffre'; Anna Granà; Maria Luisa Tumminello. Methodological Frontier in Operational Analysis for Roundabouts: A Review. Frontiers in Built Environment 2016, 2, 1 .
AMA StyleOrazio Giuffre', Anna Granà, Maria Luisa Tumminello. Methodological Frontier in Operational Analysis for Roundabouts: A Review. Frontiers in Built Environment. 2016; 2 ():1.
Chicago/Turabian StyleOrazio Giuffre'; Anna Granà; Maria Luisa Tumminello. 2016. "Methodological Frontier in Operational Analysis for Roundabouts: A Review." Frontiers in Built Environment 2, no. : 1.
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 were developed and variability of the PCEs for heavy vehicles were calculated by comparing results for a fleet of passenger cars only with those of the mixed fleet scenarios. Results show a dependence of PCEs for heavy vehicles on operational conditions, which characterise the turbo-roundabout. Assuming the values of PCEs for roundabouts provided by the 2010 Highway Capacity Manual (HCM), depending on entering manoeuvring underestimation and overestimation of the effect of heavy vehicles on the quality of traffic conditions have been found.
Orazio Giuffre'; Anna Granà; Sergio Marino; Fabio Galatioto. MICROSIMULATION-BASED PASSENGER CAR EQUIVALENTS FOR HEAVY VEHICLES DRIVING TURBO-ROUNDABOUTS. Transport 2016, 31, 295 -303.
AMA StyleOrazio Giuffre', Anna Granà, Sergio Marino, Fabio Galatioto. MICROSIMULATION-BASED PASSENGER CAR EQUIVALENTS FOR HEAVY VEHICLES DRIVING TURBO-ROUNDABOUTS. Transport. 2016; 31 (2):295-303.
Chicago/Turabian StyleOrazio Giuffre'; Anna Granà; Sergio Marino; Fabio Galatioto. 2016. "MICROSIMULATION-BASED PASSENGER CAR EQUIVALENTS FOR HEAVY VEHICLES DRIVING TURBO-ROUNDABOUTS." Transport 31, no. 2: 295-303.
This paper presents the first results of a research which applied a genetic algorithm to calibrate a microscopic traffic simulation model based on speed-density relationships. A large set of traffic data collected from the A22 Freeway, Italy, was used and a comparison was performed between the field measurements and the simulation outputs obtained for a test freeway segment by using the Aimsun microscopic simulator. The calibration was formulated as an optimization problem to be solved based on a genetic algorithm; the objective function was defined in order to minimize the differences between the simulated and real data sets in the speed-density graphs. For this purpose, the genetic algorithm tool in MATLAB®was applied. Keeping in mind the objective to automatize this process, the optimization technique was attached to Aimsun via a subroutine, so that the data transfer between the two programs could automatically happen. An external script written in Python allowed the MATLAB®software to interact with Aimsun software. A better match to the field data was reached with the optimization parameters set with the genetic algorithm. In order to check to what extent the model replicated reality, model validation was also addressed. Results showed that a genetic algorithm is usefully applicable in the calibration process of the microscopic traffic simulation model. Beneficial effects are expected by applying the suggested optimization technique since it searches for an optimum set of parameters through an efficient search method
Sandro Chiappone; Orazio Giuffre'; Anna Granà; Raffaele Mauro; Antonino Sferlazza. Traffic simulation models calibration using speed–density relationship: An automated procedure based on genetic algorithm. Expert Systems with Applications 2016, 44, 147 -155.
AMA StyleSandro Chiappone, Orazio Giuffre', Anna Granà, Raffaele Mauro, Antonino Sferlazza. Traffic simulation models calibration using speed–density relationship: An automated procedure based on genetic algorithm. Expert Systems with Applications. 2016; 44 ():147-155.
Chicago/Turabian StyleSandro Chiappone; Orazio Giuffre'; Anna Granà; Raffaele Mauro; Antonino Sferlazza. 2016. "Traffic simulation models calibration using speed–density relationship: An automated procedure based on genetic algorithm." Expert Systems with Applications 44, no. : 147-155.
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.
Orazio Giuffrè; Anna Grana; Sergio Marino; Fabio Galatioto. Passenger Car Equivalent for Heavy Vehicles Crossing Turbo-roundabouts. Transportation Research Procedia 2016, 14, 4190 -4199.
AMA StyleOrazio Giuffrè, Anna Grana, Sergio Marino, Fabio Galatioto. Passenger Car Equivalent for Heavy Vehicles Crossing Turbo-roundabouts. Transportation Research Procedia. 2016; 14 ():4190-4199.
Chicago/Turabian StyleOrazio Giuffrè; Anna Grana; Sergio Marino; Fabio Galatioto. 2016. "Passenger Car Equivalent for Heavy Vehicles Crossing Turbo-roundabouts." Transportation Research Procedia 14, no. : 4190-4199.
The critical and follow-up headways are the two gap-acceptance parameters which explain the traffic interaction of a minor street vehicle when enters the roundabout, merging into or crossing one or more circulating (major) streams. Several studies and researches provide measurements of critical and follow-up headways from real data at roundabouts. The objective of our research is to synthesize the data from the series of selected studies to interpret variation across the studies. In order to match the research goal, a systematic literature review on estimations of critical and follow-up headways at roundabouts was undertaken. Since several studies and researches developed worldwide were examined, we were able to note that the effect size varied from study to study. Thus the meta-analysis of effect sizes was performed as part of the literature review through the random-effects model. After discussing the assumptions of this model, the dispersion in effects across studies was assessed and the summary effect for each of the parameters under examination was computed. Calculations were made both for single-lane roundabouts and double-lane roundabouts, as well as for turbo roundabouts. Compared to the results of individual studies, the single (quantitative) meta-analytic estimate provides an accurate and reliable synthesis on the specific issue here addressed, and gives, with greater power of the individual reviewed studies, a comprehensive measure for the parameters of interest.
Orazio Giuffre'; Anna Granà; Maria Luisa Tumminello. Gap-accepteance parameters for roundabouts: a systematic review. European Transport Research Review 2015, 8, 1 -20.
AMA StyleOrazio Giuffre', Anna Granà, Maria Luisa Tumminello. Gap-accepteance parameters for roundabouts: a systematic review. European Transport Research Review. 2015; 8 (1):1-20.
Chicago/Turabian StyleOrazio Giuffre'; Anna Granà; Maria Luisa Tumminello. 2015. "Gap-accepteance parameters for roundabouts: a systematic review." European Transport Research Review 8, no. 1: 1-20.
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 the model replicated reality, the validation of the calibrated model was also addressed. Simulation data were used to develop the relationships among the variables of traffic flow and to calculate the passenger car equivalents for heavy vehicles by comparing a fleet of passenger cars only with a mixed fleet characterized every time by different percentages of heavy vehicles. Despite the exploratory nature of this study, some implications can be drawn: PCE estimations are small at low flow rates and increase with increased flow rates due to at low volumes there are few passenger cars that can be influenced by heavy vehicles.
Orazio Giuffre'; Anna Granà; Raffaele Mauro; Ana Bastos Silva; Sandro Chiappone. Developing Passenger Car Equivalents for Freeways by Microsimulation. Transportation Research Procedia 2015, 10, 93 -102.
AMA StyleOrazio Giuffre', Anna Granà, Raffaele Mauro, Ana Bastos Silva, Sandro Chiappone. Developing Passenger Car Equivalents for Freeways by Microsimulation. Transportation Research Procedia. 2015; 10 ():93-102.
Chicago/Turabian StyleOrazio Giuffre'; Anna Granà; Raffaele Mauro; Ana Bastos Silva; Sandro Chiappone. 2015. "Developing Passenger Car Equivalents for Freeways by Microsimulation." Transportation Research Procedia 10, no. : 93-102.
In the paper, a choice criterion between flower roundabouts and double-lane roundabouts is proposed, focusing on operational benefits that can derive from one scheme over the other, and outlining a general framework for benefit-cost analysis. In order to assess operational benefits of innovative roundabouts over modern roundabouts, a comparative analysis was made. Capacity was estimated using gap-acceptance models. In detail, assuming the dichotomic shifted negative exponential distribution to model headways in circulating streams, the Hagring formula was adjusted to obtain entry capacity estimations at roundabout approaches where entering vehicles face one or two conflicting flows. Based on the control delay, the suitability domains and indifference areas were constructed. Thus, a sensitivity analysis to changes in traffic demand for operational benefits of flower roundabouts over double-lane roundabouts was carried out and discussed. At last, evidence for new installations and conversion of existing roundabouts can be found.
Tullio Giuffre'; Anna Grana; Roberta Marino; S. Marino. Flower Roundabouts And Double-Lane Roundabouts: A Comparative Performance Analysis. Archives of Civil Engineering 2014, 60, 349 -365.
AMA StyleTullio Giuffre', Anna Grana, Roberta Marino, S. Marino. Flower Roundabouts And Double-Lane Roundabouts: A Comparative Performance Analysis. Archives of Civil Engineering. 2014; 60 (3):349-365.
Chicago/Turabian StyleTullio Giuffre'; Anna Grana; Roberta Marino; S. Marino. 2014. "Flower Roundabouts And Double-Lane Roundabouts: A Comparative Performance Analysis." Archives of Civil Engineering 60, no. 3: 349-365.
Starting from consideration that urban intersections are sites with promise for safety and operational improvements, the paper describes the steps taken to develop a crash predictive model for estimating the safety performance of urban unsignalized intersections located in Palermo, Italy. The focus is on unsignalized four-legged one-way intersections widespread in Italian downtowns. The sample considered in the study consist of 92 intersections in Palermo, Italy. For the study were collected crashes occurred in the sites during the years 2006-2012, geometric design and functional characteristics and traffic flow. Results showed that data were overdispersed and NB1 distributed. In order to account for the correlation within responses Generalized Estimating Equations (GEE) were used under different working correlation matrices.
Tullio Giuffre'; Anna Granà; R A Marino; S. Marino. Estimating the Safety Performance Function for Urban Unsignalized Four-Legged One-Way Intersections in Palermo, Italy. Archives of Civil Engineering 2014, 60, 41 -54.
AMA StyleTullio Giuffre', Anna Granà, R A Marino, S. Marino. Estimating the Safety Performance Function for Urban Unsignalized Four-Legged One-Way Intersections in Palermo, Italy. Archives of Civil Engineering. 2014; 60 (1):41-54.
Chicago/Turabian StyleTullio Giuffre'; Anna Granà; R A Marino; S. Marino. 2014. "Estimating the Safety Performance Function for Urban Unsignalized Four-Legged One-Way Intersections in Palermo, Italy." Archives of Civil Engineering 60, no. 1: 41-54.