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Roundabouts Performance in Road Transport Networks—Future Challenges, Problems and Issues

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A special issue of Sustainability (ISSN 2071-1050). This special issue belongs to the section "Sustainable Transportation".

Deadline for manuscript submissions: closed (31 December 2023) | Viewed by 23003

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Prof. Dr. Elżbieta Macioszek

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Department of Transport Systems, Traffic Engineering and Logistics, Faculty of Transport and Aviation Engineering, Silesian University of Technology, Krasińskiego 8 Street, 40-019 Katowice, Poland
Interests: road traffic engineering; road and intersections capacity analysis; measurements; traffic modeling; research and traffic flow analysis; transport infrastructure; functional analysis; transport systems and processes modeling; transportation engineering
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Dr. Anna Grana

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Guest Editor

Department of Engineering, University of Palermo, 90128 Palermo, Italy
Interests: sustainable geometric road design; road safet and remodeling; microscopic traffic simulation
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Prof. Dr. Tomaž Tollazzi

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Guest Editor

Faculty of Civil Engineering, Transportation Engineering and Architecture, University of Maribor, Smetanova 17, 2000 Maribor, Slovenia
Interests: sustainable safe road infrastructure design; with particular focus on intersections; interchanges; roundabouts; vulnerable road users

Prof. Dr. Tullio Giuffrè

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Guest Editor

Faculty of Engineering and Architecture, University of Enna Kore, Viale della Cooperazione, 94100 Enna, Italy
Interests: road safety evaluation; road design; connected automated vehicle operation; transport infrastructure; traffic operation modeling; statistical analysis
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Special Issue Information

Dear Colleagues,

Many different layouts and sizes can be used to design modern roundabouts. The type of roundabout is determined by various factors, such as space availability, traffic volume, expected and-users, location, etc. Roundabouts are often used to improve traffic safety and capacity in urban and rural areas and can also be employed as a measure for traffic calming instead of signal-controlled intersections.

This Special Issue will consist of papers describing the synthesis of current theory and practice of planning, design, operation, and safety of modern roundabouts, with special attention on future challenges and will be of interest to scientists dealing with roundabouts problems and issues and generally involved in road traffic engineering as well as design, traffic, and maintenance engineers. Other major areas of interest with regard to roundabouts include but are not limited to:

Efficiency evaluation;
Traffic capacities and delays;
Issues related to pedestrians, bicyclists, and visually impaired users;
Costs and location criteria;
Road traffic measurements, data analysis;
Traffic flow modeling;
Signing and pavement markings;
Signalized roundabouts;
Experimental analysis for roundabouts;
Autonomous vehicles on roundabouts;
Driver behavior patterns on roundabouts;
Conflicts at roundabouts.

Prof. Elżbieta Macioszek
Prof. Anna Grana
Prof. Dr. Tomaž Tollazzi
Dr. Tullio Giuffrè
Guests Editors

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Keywords

road traffic engineering
road transport network
modern roundabouts

Published Papers (11 papers)

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Research

21 pages, 4408 KiB

Open AccessArticle

Roundabout Trajectory Planning: Integrating Human Driving Models for Autonomous Vehicles

by Salvatore Leonardi and Natalia Distefano

Sustainability 2023, 15(23), 16288; https://doi.org/10.3390/su152316288 - 24 Nov 2023

Viewed by 711

Abstract

This research investigates the utilization of human driving models in autonomous vehicles, particularly in scenarios with minimal or no interactions with other vehicles. Human driving models provide valuable insights into driver behavior and play a crucial role in shaping the behavior of autonomous vehicles, enhancing their performance and user experience. The primary focus of this study is the creation of a planning model for autonomous vehicles when navigating roundabouts in the absence of traffic. This model seeks to emulate human driving behavior, ensuring predictability, safety, the optimization of traffic flow, and adaptation to various roundabout geometries. To achieve this, the research introduces a trajectory model that takes into account geometric attributes and speed variations within roundabouts. The model is calibrated using empirical data and generalizes parameters through statistical regression methodologies. In particular, speed profile modeling is evaluated for its consistency in creating plans that faithfully replicate human driving behavior in roundabouts. While the study presents a promising approach, it acknowledges limitations related to the model’s reliance on geometric attributes and its inability to account for external factors like weather conditions. This research underscores the importance of bridging the gap between theoretical research and practical application, with the aim of enhancing safety and the overall user experience in real-world driving scenarios. Full article

(This article belongs to the Special Issue Roundabouts Performance in Road Transport Networks—Future Challenges, Problems and Issues)

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24 pages, 15295 KiB

Open AccessArticle

Design of Turbo-Roundabouts Based on the Rules of Vehicle Movement Geometry on Curvilinear Approaches

by Alicja Barbara Sołowczuk and Weronika Benedysiuk

Sustainability 2023, 15(18), 13882; https://doi.org/10.3390/su151813882 - 18 Sep 2023

Cited by 1 | Viewed by 726

Abstract

The construction of turbo-roundabouts is an increasingly frequent choice when it comes to improving flow capacity and traffic safety at road intersections. The existing design guidelines, as a rule, give parameters for turbo-roundabouts with approaches set at right angles to each other. The article presents turbo-roundabout design methods, taking into account swept path analyses of the chosen design vehicles when the approach legs are curvilinear and oriented to each other at a non-right angle. Based on the analysis of three different design vehicles, it was proven that their swept paths have a major influence on the geometrical parameters of the roundabout and, consequently, on the land take area, i.e., they can significantly impact the project’s construction costs. In the case of curvilinear approaches, which are oriented to each other at a non-right angle, it is impossible to impose on the designer specific values of the circulatory lane widths and the entry and exit curve radii as they depend primarily on the chosen design vehicle. The aim of the article was to demonstrate that in the case of the curvilinear approach on the Basic type turbo-roundabout, the design process should include the swept path analysis for the chosen design vehicle for each of the approaches. This should lead to the design of wider swept paths and higher curve lane divider entry and exit radii. Full article

(This article belongs to the Special Issue Roundabouts Performance in Road Transport Networks—Future Challenges, Problems and Issues)

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28 pages, 23495 KiB

Open AccessArticle

Design Study for the Construction of Turbo Roundabouts under Constrained Site Conditions

by Alicja Sołowczuk and Stanisław Majer

Sustainability 2023, 15(17), 13220; https://doi.org/10.3390/su151713220 - 03 Sep 2023

Viewed by 1085

Abstract

Turbo-roundabouts are one of the most frequently recommended road junction design options when it comes to increasing traffic capacity and traffic safety. This is in particular true of suburban areas, with dominant traffic flow on the main road and moderate traffic flow on the side road. Other intersections handling local traffic and considerably constricting the availability of space are usually located in the vicinity of such intersections. Another factor contributing to the limited availability of land for construction in these locations is the presence of surrounding residential housing. Then, choosing the suitable turbo-roundabout type becomes the main issue. The article presents a case study for the selection of a type of turbo roundabout under the conditions of considerably constricted land availability based on the analysis of the provision of a swept path for the chosen design vehicles. The article considers the standard egg-type turbo-roundabouts, “look-a-like” type turbo-roundabouts, non-standard “flattened” turbo-roundabouts and ellipse-based roundabouts, with non-standard geometries of the truck apron and central island. For each of the analysed roundabout types, setting-out methods were described in detail, allowing the designer to quickly select a type of roundabout suitable for the specific constrained site conditions. This article analyses the applicability of non-standard turbo roundabouts for three area types: LUDA low urbanisation degree area, BA built-up area and CDA highly commercially developed area along the side road, wherever standard roundabouts are not practicable due to constraints imposed by existing buildings, canals or any other obstacles found at the project site. Full article

(This article belongs to the Special Issue Roundabouts Performance in Road Transport Networks—Future Challenges, Problems and Issues)

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19 pages, 10057 KiB

Open AccessArticle

A Conflict-Based Safety Diagnosis of SCI Roundabouts Using a Surrogate Safety Measure Model

by Mehrzad Hasanvand, Amir Saman Abdollahzadeh Nasiri, Omid Rahmani, Khaled Shaaban and Hossein Samadi

Sustainability 2023, 15(17), 13166; https://doi.org/10.3390/su151713166 - 01 Sep 2023

Viewed by 1050

Abstract

Recently, the surrogate safety assessment model has been considered for the safety performance analysis of roundabouts. This model can perform a detailed analysis of conflicts based on the trajectory data of vehicles inside the roundabout. The Separated Central Island (SCI) roundabout, as one of the roundabouts with distinct geometrical characteristics, holds the potential for safety evaluation using the conflict-based method. Therefore, in this study, a safety diagnosis of an SCI roundabout was conducted for the first time. In this study, a safety diagnosis procedure for SCI roundabout was first defined; for this purpose, vehicle trajectory data were obtained using an Unnamed Aerial Vehicle (UAV) and then entered into Surrogate Safety Measure Model software (SSAM 3.0). A case study was conducted on the only SCI roundabout in Iran, located in Mashhad. The parameters of Time-to-Collision (TTC), maximum speed difference of two vehicles involved in a collision (MaxΔV), and maximum speed of vehicles in collision (MaxS) were utilized to determine the type and severity of conflicts and risk analysis. The results of roundabout risk analysis showed that the severity level of conflicts is mainly of the injury type and that the lowest severity of conflicts is related to fatality. In addition, the highest frequency of injury conflicts is associated with lane-change conflict and the lowest frequency is linked to rear-end conflict. The highest and lowest frequency of damage conflicts are related to crossing and lane-change conflicts, respectively. After overall risk scoring, the severity level of conflicts is mainly related to injury type and the lowest severity of conflicts is associated with fatality; 31% of the total conflicts obtained are of the damaging type, and 69% are of the injury type. Finally, comparing the results of the conflict data with the 8-year crash data in such roundabouts confirms that in the absence of crash data in such roundabouts traffic engineers can use the roundabout analysis based on this study to predict the safety situation of such roundabouts before implementing engineering processes. Full article

(This article belongs to the Special Issue Roundabouts Performance in Road Transport Networks—Future Challenges, Problems and Issues)

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17 pages, 3293 KiB

Open AccessArticle

Development of Artificial Intelligence Based Safety Performance Measures for Urban Roundabouts

by Fayez Alanazi, Ibrahim Khalil Umar, Sadi Ibrahim Haruna, Mahmoud El-Kady and Abdelhalim Azam

Sustainability 2023, 15(14), 11429; https://doi.org/10.3390/su151411429 - 23 Jul 2023

Viewed by 852

Abstract

A reliable model for predicting crash frequency at roundabouts is an essential tool for evaluating the safety measures of a roundabout. This study developed a hybrid PSO-ANN model by optimizing the modeling parameters of the classical artificial neural network (ANN) model with the particle swarm optimization algorithm (PSO). The performance accuracy of the models was evaluated using the mean absolute error (MAE), root mean square error (RMSE), and determination coefficients (DC). The PSO-ANN model predicted the crash frequency with very good accuracy at the testing stage (DC = 0.7935). The hybrid model could improve the performance of the classical ANN model by up to 23.3% in the training stage and 16.9% in the testing stage. In addition to the statistical measures, graphical approaches (scatter and violin plots) were also used for evaluating the models’ accuracy. Both statistical and graphical evaluation techniques prove the reliability and accuracy of the proposed hybrid model in predicting the crash frequency at roundabouts. Full article

(This article belongs to the Special Issue Roundabouts Performance in Road Transport Networks—Future Challenges, Problems and Issues)

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14 pages, 1498 KiB

Open AccessArticle

Impact of Autonomous Vehicles on Roundabout Capacity

by Othmane Boualam, Attila Borsos, Csaba Koren and Viktor Nagy

Sustainability 2022, 14(4), 2203; https://doi.org/10.3390/su14042203 - 15 Feb 2022

Cited by 13 | Viewed by 2769

Abstract

Studying the impact of AVs on our road infrastructure offers a lot of potential in the transportation domain; one of these issues is how capacity will be affected. This paper presents a contribution to this research area by investigating the impact of AVs on the capacity of single-lane roundabouts using a microsimulation model. For the development of the model, a roundabout situated in Győr (Hungary) was selected and field data on the roundabout geometric characteristics as well as traffic volumes were used. Simulations using Vissim were run for various scenarios based on varying input traffic volumes and market penetration rates of AVs to assess queue lengths. The highway capacity manual (HCM) roundabout model was used to estimate the capacity of the existing roundabout. Values of follow-up times and critical gaps were set to decreasing as the penetration rate of AVs increases. The results demonstrated that 20% and 40% AVs in the flow would increase leg capacities by about 10% and 20%, respectively. Furthermore, a reduction in excessive queue lengths was estimated and capacities and queue lengths were calculated by legs. It was found that these are highly influenced by the distribution of flows among legs, and the share of flows in various directions. Full article

(This article belongs to the Special Issue Roundabouts Performance in Road Transport Networks—Future Challenges, Problems and Issues)

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14 pages, 334851 KiB

Open AccessEditor’s ChoiceArticle

Safety Evaluation of Flower Roundabout Considering Autonomous Vehicles Operation

by Alessandro Severino, Giuseppina Pappalardo, Salvatore Curto, Salvatore Trubia and Isaac Oyeyemi Olayode

Sustainability 2021, 13(18), 10120; https://doi.org/10.3390/su131810120 - 09 Sep 2021

Cited by 31 | Viewed by 2722

Abstract

With the significant technological growth that affected autonomous vehicles in the last decade, several consequences occurred as: human factor exclusion, entry and exit manoeuvres precision from roundabouts, and headway reduction. In this paper, it was carried out a microsimulation approach study that aims to evaluate benefits in terms of safety obtained with flower roundabouts in a scenario where traffic is characterized by conventional vehicles “CVs” and Connected Autonomous Vehicles “CAVs”. This study focused on the evaluation of CAVs and CVs operation with the presence of the so called “weak users” or rather, pedestrians and bikes. Then, simulated scenarios were characterized by the presence of zebra-crossings in main roads, positioned at 20 m from circulatory carriageway edges. Micro simulation choice is due to the absence of survey data collection because the presence of CAVs in ordinary traffic is still minimal. The micro simulation was carried out through VISSIM, so it was operated with a specific methodological path, consisting, in the application, of O–D matrix based on real cases, in order to achieve an assessment of potential conflicts in relation with the increase in CAVs. Simulation results showed that higher safety levels were achieved for special cases of O–D distribution and with CAVs present. Finally, considering crash absence in results related to CAVs presence, safety interventions of such roundabout types have to be thorough. There were 10 O/D matrices analysed through VISSIM considering parameters as: average tail length, maximum tail length, average speed, vehicles, and number of stops quantity. As reported in the conclusion section, O/D matrices that showed minimum conflicts and maximum dynamic performances were identified. Full article

(This article belongs to the Special Issue Roundabouts Performance in Road Transport Networks—Future Challenges, Problems and Issues)

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14 pages, 2647 KiB

Open AccessEditor’s ChoiceArticle

Safety Evaluation of Turbo-Roundabouts with and without Internal Traffic Separations Considering Autonomous Vehicles Operation

by Tullio Giuffrè, Anna Granà and Salvatore Trubia

Sustainability 2021, 13(16), 8810; https://doi.org/10.3390/su13168810 - 06 Aug 2021

Cited by 12 | Viewed by 2061

Abstract

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. Full article

(This article belongs to the Special Issue Roundabouts Performance in Road Transport Networks—Future Challenges, Problems and Issues)

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15 pages, 5029 KiB

Open AccessArticle

Data-Driven Scenario Specification for AV–VRU Interactions at Urban Roundabouts

by Andreas Keler, Patrick Malcolm, Georgios Grigoropoulos, Seyed Abdollah Hosseini, Heather Kaths, Fritz Busch and Klaus Bogenberger

Sustainability 2021, 13(15), 8281; https://doi.org/10.3390/su13158281 - 24 Jul 2021

Cited by 5 | Viewed by 1939

Abstract

Detailed specifications of urban traffic from different perspectives and scales are crucial for understanding and predicting traffic situations from the view of an autonomous vehicle (AV). We suggest a data-driven specification scheme for maneuvers at different design elements of the built infrastructure and focus on urban roundabouts in Germany. Based on real observations, we define classes of maneuvers, interactions and driving strategies for cyclists, pedestrians and motorized vehicles and define a matrix for merging different maneuvers, resulting in more complex interactions. The sequences of these interactions, which partially consist of explicit communications, are extracted from real observations and adapted into microscopic traffic flow simulations. The simulated maneuver sequences are then visualized in 3D environments and experienced by bicycle simulator test subjects. Using trajectory segments (in fictional space) from two conducted simulator studies, we relate the recorded movement patterns of test subjects with observed cyclists in reality. Full article

(This article belongs to the Special Issue Roundabouts Performance in Road Transport Networks—Future Challenges, Problems and Issues)

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14 pages, 1231 KiB

Open AccessArticle

Modeling the Influence of Roundabout Deflection on Its Efficiency as a Noise Abatement Measure

by Saša Ahac, Maja Ahac, Josipa Domitrović and Vesna Dragčević

Sustainability 2021, 13(10), 5407; https://doi.org/10.3390/su13105407 - 12 May 2021

Cited by 8 | Viewed by 2524

Abstract

Challenges that emerge in roundabout design are mostly related to space constrictions and provision of appropriate deflection around the central island. This can result in speed profiles on roundabouts that might reduce their potential as a noise abatement measure. Because of this, the impact of a roundabout on noise levels and its applicability as a traffic calming device and a noise abatement measure should be investigated in the early design stage, by modeling noise levels. In this paper, the following hypothesis is tested: vehicle movement trajectories, defined during the fastest path performance check in roundabout early design phase, can be used as the road traffic noise sources when modeling noise at roundabouts using static noise model. This procedure (1) simplifies the preparation of the noise model, (2) results in a model that is closer to the real-world in terms of traffic flow conditions, (3) allows the noise calculations in the early stages of roundabout design, and (4) includes the influence of roundabout deflection on calculated noise levels. The abovementioned simplifications of the road traffic noise modeling process should encourage the optimization of roundabout geometry in terms of its noise reduction capabilities in the preliminary design phase of these intersections. Full article

(This article belongs to the Special Issue Roundabouts Performance in Road Transport Networks—Future Challenges, Problems and Issues)

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21 pages, 2466 KiB

Open AccessArticle

Roundabout Entry Capacity Calculation—A Case Study Based on Roundabouts in Tokyo, Japan, and Tokyo Surroundings

by Elżbieta Macioszek

Sustainability 2020, 12(4), 1533; https://doi.org/10.3390/su12041533 - 18 Feb 2020

Cited by 37 | Viewed by 4158

Abstract

The article presents the calculation of roundabout entry capacity as a case study based on roundabouts located in Tokyo, Japan, and Tokyo surroundings. The analysis was conducted as part of the project entitled “Analysis of the applicability of the author’s method of roundabouts entry capacity calculation developed for the conditions prevailing in Poland to the conditions prevailing at roundabouts in Tokyo (Japan) and in the Tokyo surroundings”. The main aim and the research question was whether the author’s model of roundabouts entry capacity calculation constructed for the conditions prevailing in Poland after calibration is suitable to calculate roundabout entry capacity of roundabouts located in Tokyo and in the Tokyo surroundings. In order to perform the calibration in 2019, measurements were taken at the single-lane roundabouts located in Tokyo and Tokyo surroundings. The model calibration revealed that it is possible to evaluate the entry capacity of roundabouts located in Tokyo and in Tokyo surroundings using the author’s model. Full article

(This article belongs to the Special Issue Roundabouts Performance in Road Transport Networks—Future Challenges, Problems and Issues)

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