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Sustainable and Safe Roundabouts

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

Deadline for manuscript submissions: closed (31 December 2021) | Viewed by 17167

Special Issue Editors


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Guest Editor
Department of Civil Engineering, University of Calabria, Arcavacata Campus, 87036 Rende, Italy
Interests: road pavement surface performances; bituminous materials; recycled and sustainable road materials; sustainable mobility; road safety and driver behavior; traffic microsimulation; geometric design and performance analysis of roundabouts; surrogate safety indicators
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
Department of Civil Engineering, University of Calabria, Arcavacata Campus, 87036 Rende, Italy
Interests: transportation modeling; sustainable mobility; transportation planning; ITS mobility management; traffic simulation; road pavement surface performances; sustainable road materials; road safety; traffic microsimulation; surrogate safety indicators; road geometric design and performance analysis of roundabouts
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Road design, with particular reference to intersections regulated with a roundabout scheme, has undergone a profound conceptual evolution in the last 50 years. The reasons for this evolution are to be found in the ever-growing demand for performance by drivers (speed, waiting times, capacity, etc.), together with a higher degree of traffic safety and greater sustainability of road transport. In this direction, the design of roundabouts has passed from the oldest roundabout in the world to the Piccadilly Circus, London (1819, United Kingdom) to the more modern Turboroundabouts, the first of which was built in Barendrecht (2000, Holland).Fortunately, this evolution has always been associated with the production of a large number of studies and research useful for decoding and improving the performance, safety, and sustainability of roundabout junctions. Nevertheless, there are still topics worth investigating, such as the safety of vulnerable road users, the potential conflicts in roundabouts when using surrogate safety measures, the use of microsimulation tools to evaluate the improvement in various intersection solutions in terms of performance and safety, and the environmental benefits of new schemes for roundabouts.This Special Issue aims to collect scientific and research contributions that can help to reach these goals.

Prof. Rosolino Vaiana
Dr. Vincenzo Gallelli
Guest Editors

Manuscript Submission Information

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Keywords

  • roundabouts;
  • traffic safety;
  • sustainable road transport;
  • traffic flow modeling;
  • roundabout capacity;
  • traffic simulation;
  • roundabouts design;
  • fuel consumption and emissions;
  • surrogate safety measures;
  • safety of vulnerable road users.

Published Papers (5 papers)

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Research

15 pages, 1677 KiB  
Article
Operational and Safety Management at Intersections: Can the Turbo-Roundabout Be an Effective Alternative to Conventional Solutions?
by Vincenzo Gallelli, Giusi Perri and Rosolino Vaiana
Sustainability 2021, 13(9), 5103; https://0-doi-org.brum.beds.ac.uk/10.3390/su13095103 - 01 May 2021
Cited by 8 | Viewed by 3327
Abstract
The European Union policy strategies on the sustainability of the transport system pursue the goals of maximizing safety and environmental benefits and reducing the severity and frequency of crashes, congestion, and pollutant emission rates. A common issue is the planning of the most [...] Read more.
The European Union policy strategies on the sustainability of the transport system pursue the goals of maximizing safety and environmental benefits and reducing the severity and frequency of crashes, congestion, and pollutant emission rates. A common issue is the planning of the most effective solution for operational and safety management at intersections. In this study, an egg turbo roundabout is proposed as the alternative solution to a conventional roundabout in Southern Italy which suffers from traffic congestion. A comparative analysis is carried out using microsimulation techniques to investigate the safety effects and operational improvements of converting a traditional priority intersection into standard roundabout or turbo roundabout layout. In particular, the VISSIM software is used to explore the most relevant operational performance measures: queue length, travel times and delays. The lowest values of these measurements are recorded for the simulated turbo roundabout, thus making this scheme more appropriate in terms of operational performances. With regard to safety analysis, the Surrogate Safety Assessment Model (SSAM) is used to collect information on the predicted number of conflicts, the probability, and severity of the potential collisions. The results suggest that, for the specific case study, the safety levels of the standard roundabout and the turbo roundabout are approximately comparable. Full article
(This article belongs to the Special Issue Sustainable and Safe Roundabouts)
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16 pages, 4368 KiB  
Article
Safety and Efficiency Analysis of Turbo Roundabout with Simulations Based on the Lujiazui Roundabout in Shanghai
by Qiujia Liu, Jiali Deng, Yifan Shen, Wenxin Wang, Zhan Zhang and Linjun Lu
Sustainability 2020, 12(18), 7479; https://0-doi-org.brum.beds.ac.uk/10.3390/su12187479 - 11 Sep 2020
Cited by 12 | Viewed by 4291
Abstract
Traditional multilane roundabouts have many branch lanes without traffic signs and channelization, which leads to a high tendency for traffic collisions. Turbo roundabouts are a new design that has the potential to reduce lane-change conflicts using canalization to force drivers to keep in [...] Read more.
Traditional multilane roundabouts have many branch lanes without traffic signs and channelization, which leads to a high tendency for traffic collisions. Turbo roundabouts are a new design that has the potential to reduce lane-change conflicts using canalization to force drivers to keep in specific lanes based on their intended destination. This paper evaluates the safety and efficiency performance of turbo roundabouts for the case of a five-leg roundabout called Lujiazui in Shanghai and provides design and construction guidelines when applying the turbo design. The models for the Lujiazui roundabout and the reconstructed turbo version were built in Vissim, and a comprehensive series of experiments under different traffic volumes and central island radii was performed. Afterward, the conflict statistics extracted from the trajectory files in the Surrogate Safety Assessment Model (SSAM) were analyzed using the conflict severity index (CSI) and were then integrated to calculate the modified conflict frequency (MCF) for safety performance evaluation. A comparative efficiency analysis was also conducted as a supplement. Based on the results, the relative characteristics for safety and efficiency between the turbo and original designs of the Lujiazui roundabout were analyzed. Suggestions to apply the turbo design on a five-leg roundabout are introduced. Full article
(This article belongs to the Special Issue Sustainable and Safe Roundabouts)
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13 pages, 42156 KiB  
Article
Functions, Capacities, and Traffic Safety Characteristics of Some Types of Two-Level Roundabouts
by Tomaž Tollazzi, Marco Guerrieri, Goran Jovanović and Marko Renčelj
Sustainability 2020, 12(17), 6914; https://0-doi-org.brum.beds.ac.uk/10.3390/su12176914 - 25 Aug 2020
Cited by 6 | Viewed by 2480
Abstract
Over recent decades, roundabouts have become increasingly used when building new at-grade intersections or up-grade junctions all over the world. Consequently, control of traffic flows at at-grade intersections and up-grade junctions using roundabouts creates unique design problems. Nowadays, ‘alternative’ types of roundabouts have [...] Read more.
Over recent decades, roundabouts have become increasingly used when building new at-grade intersections or up-grade junctions all over the world. Consequently, control of traffic flows at at-grade intersections and up-grade junctions using roundabouts creates unique design problems. Nowadays, ‘alternative’ types of roundabouts have started to become very popular, especially because of their advantages compared with ‘standard’ roundabouts and standard types of up-grade junctions. Some of these alternative types of roundabouts are two-level roundabouts, which are still currently in the development phase. It is for this reason that they can be called ‘theoretical roundabouts’. Two-level roundabouts are particularly useful in urban and suburban areas with space limitations due to their relatively small footprint. This paper illustrates three new alternative types of two-level roundabouts—‘target’, ‘four flyover’, and ‘roundabout with left and right bypasses’—as well as their functions, capacities, and traffic safety characteristics. Full article
(This article belongs to the Special Issue Sustainable and Safe Roundabouts)
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21 pages, 2977 KiB  
Article
New Extensions and Applications of the Modified Chumanov Model for Calculating Entry Capacity of Single-Lane Roundabouts
by Andrea Pompigna, Marco Guerrieri and Raffaele Mauro
Sustainability 2020, 12(15), 6122; https://0-doi-org.brum.beds.ac.uk/10.3390/su12156122 - 30 Jul 2020
Cited by 7 | Viewed by 2412
Abstract
Over the past decades many models for roundabout capacity have been proposed. Attention to this research sector has never stopped and still today new formulations are always being studied, especially in view of their direct application in design practice. This paper reports the [...] Read more.
Over the past decades many models for roundabout capacity have been proposed. Attention to this research sector has never stopped and still today new formulations are always being studied, especially in view of their direct application in design practice. This paper reports the first noteworthy results of a research concerning the Modified Chumanov (MC) model, which can be used to estimate the capacity of single-lane roundabout entrances. After a detailed examination of the original model recommended by the Russian guidelines for small urban roundabouts, the paper proposes some extensions which allow using the revised model even for larger intersections. The MC model also includes some parameterizations that allow its application with different road pavement surface conditions (i.e., dry and wet conditions). The MC entry capacity model, as function of circulating flow and other parameters dependent on geometry and environmental conditions, was compared with 15 widespread models considering a typical medium-sized single-lane roundabout. A validation test was carried out considering four capacity–circulating flow datasets from the literature. The proposed MC model showed good flexibility in adapting to data. This flexibility appears better than the most recent models by Highway Capacity Manual, in the absence of local calibration of the psychotechnical parameters. Full article
(This article belongs to the Special Issue Sustainable and Safe Roundabouts)
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14 pages, 4483 KiB  
Article
Critical Gap Comparison between One-, Two-, and Three-Lane Roundabouts in Qatar
by Khaled Shaaban and Hassan Hamad
Sustainability 2020, 12(10), 4232; https://0-doi-org.brum.beds.ac.uk/10.3390/su12104232 - 21 May 2020
Cited by 15 | Viewed by 3224
Abstract
A critical gap value of a roundabout is mainly affected by the interactions between the circulating vehicles and vehicles entering the roundabout. These interactions are impacted by many factors, including the number of circulating lanes, the aggressiveness of local drivers, vehicle types, and [...] Read more.
A critical gap value of a roundabout is mainly affected by the interactions between the circulating vehicles and vehicles entering the roundabout. These interactions are impacted by many factors, including the number of circulating lanes, the aggressiveness of local drivers, vehicle types, and the number of approaching lanes. Therefore, it is essential to locally investigate critical gap values before conducting any studies to improve capacity and delay at roundabouts. The purpose of this study is to measure and compare the critical gap values for different types of roundabouts in Qatar. More than 10,000 measurements were collected. The results showed that the critical gap values were 2.24 s, 2.55 s, and 2.40 s for the one-, two-, and three-lane roundabouts, respectively. These values are also quite low when compared to values calculated in other countries, which can be an indication of driver aggressiveness and risky behavior. The study is one of the first efforts to compare three types of roundabouts and to understand the difference in operation between them in this region. The results of this study can help engineers, planners, and public agencies to plan, study, and design similar facilities. Full article
(This article belongs to the Special Issue Sustainable and Safe Roundabouts)
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