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This study investigated the nature and causes of unsafe driving behavior at roundabouts through an on-road study. Four urban double-lane roundabouts with different layouts were selected for an on-road study. Sixty-six drivers (41 males and 25 females) aged 18–65 years took part in the study. Unsafe behaviors observed during the in situ survey were divided into three different categories: entry unsafe behaviors, circulation unsafe behaviors, and exit unsafe behaviors. Three chi-square automatic interaction detection (CHAID) analyses were developed in order to analyze the influence of roundabout characteristics and maneuvers on unsafe behaviors at double-lane roundabouts. The results confirmed the awareness that double-lane roundabouts are unsafe and inadvisable. More than half of unsafe driving behaviors were found to be entry unsafe behaviors. Moreover, the entry radius was found to be the geometric variable most influencing unsafe driving behaviors.
Giulia Pulvirenti; Natalia Distefano; Salvatore Leonardi; Tomaz Tollazzi. Are Double-Lane Roundabouts Safe Enough? A CHAID Analysis of Unsafe Driving Behaviors. Safety 2021, 7, 20 .
AMA StyleGiulia Pulvirenti, Natalia Distefano, Salvatore Leonardi, Tomaz Tollazzi. Are Double-Lane Roundabouts Safe Enough? A CHAID Analysis of Unsafe Driving Behaviors. Safety. 2021; 7 (1):20.
Chicago/Turabian StyleGiulia Pulvirenti; Natalia Distefano; Salvatore Leonardi; Tomaz Tollazzi. 2021. "Are Double-Lane Roundabouts Safe Enough? A CHAID Analysis of Unsafe Driving Behaviors." Safety 7, no. 1: 20.
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.
Tomaž Tollazzi; Marco Guerrieri; Goran Jovanović; Marko Renčelj. Functions, Capacities, and Traffic Safety Characteristics of Some Types of Two-Level Roundabouts. Sustainability 2020, 12, 6914 .
AMA StyleTomaž Tollazzi, Marco Guerrieri, Goran Jovanović, Marko Renčelj. Functions, Capacities, and Traffic Safety Characteristics of Some Types of Two-Level Roundabouts. Sustainability. 2020; 12 (17):6914.
Chicago/Turabian StyleTomaž Tollazzi; Marco Guerrieri; Goran Jovanović; Marko Renčelj. 2020. "Functions, Capacities, and Traffic Safety Characteristics of Some Types of Two-Level Roundabouts." Sustainability 12, no. 17: 6914.
Tomaž Tollazzi; Raffaele Mauro; Daiva Žilionienė; Irena I. Otković; Nikiforos Stamatiadis. Modern Roundabouts: A Challenge of the Future. Journal of Advanced Transportation 2019, 2019, 1 -2.
AMA StyleTomaž Tollazzi, Raffaele Mauro, Daiva Žilionienė, Irena I. Otković, Nikiforos Stamatiadis. Modern Roundabouts: A Challenge of the Future. Journal of Advanced Transportation. 2019; 2019 ():1-2.
Chicago/Turabian StyleTomaž Tollazzi; Raffaele Mauro; Daiva Žilionienė; Irena I. Otković; Nikiforos Stamatiadis. 2019. "Modern Roundabouts: A Challenge of the Future." Journal of Advanced Transportation 2019, no. : 1-2.
Analysis of literature shows that "modern roundabouts" nowadays exist in all European countries, as well as in more than 60 countries elsewhere in the world. Nowadays, a growing number of studies, presented in scientific and professional literature, point out a poor trac safety characteristics of "standard" two-lane roundabouts and lower capacity then was expected. These problems are resolved in more ways in dierent countries; however the solution, whereby the number of conflict spots is diminished has proven to be the most successful. Lower number of conflict spots is one of characteristics of the alternative types of roundabouts. The alternative types of roundabouts are usually more recent and implemented only in certain countries. It is typical for them that they dier from "standard" one- and two-lane roundabouts in one or more design elements, while the purpose of their implementation is also specific. This paper illustrate four relative new alternative types of roundabouts – "turbo", "flower", "target" and "four flyover" roundabouts and their comparison from designing, capacity and trac – safety point of view.
Tomaž Tollazzi; Raffaele Mauro; Marco Guerrieri; Marko Rençelj. Comparative Analysis of Four New Alternative Types of Roundabouts: "Turbo", "Flower", "Target" and "Four-Flyover" Roundabout. Periodica Polytechnica Civil Engineering 2016, 60, 51 -60.
AMA StyleTomaž Tollazzi, Raffaele Mauro, Marco Guerrieri, Marko Rençelj. Comparative Analysis of Four New Alternative Types of Roundabouts: "Turbo", "Flower", "Target" and "Four-Flyover" Roundabout. Periodica Polytechnica Civil Engineering. 2016; 60 (1):51-60.
Chicago/Turabian StyleTomaž Tollazzi; Raffaele Mauro; Marco Guerrieri; Marko Rençelj. 2016. "Comparative Analysis of Four New Alternative Types of Roundabouts: "Turbo", "Flower", "Target" and "Four-Flyover" Roundabout." Periodica Polytechnica Civil Engineering 60, no. 1: 51-60.
In order to prevent accidents between motorized and non-motorized participants, the following different strategies are known in general: eliminate the risk; separate the non-motorized participants from the risk situation; if that is not possible—insulate the risk; if that is not possible—modify the risk; if that does not work—equip the road infrastructure (with additional road furniture), than control the risk behavior (watch, supervise); when it is not enough—inform and instruct non-motorized (also motorized) participants (through brochures, leaflets, newspapers, television…); when that cannot be done—restrict to approach the risk zone (by legislation or prohibition); the last action to be taken is to start the emergency (reconstruction and new—more safe solution).
Tomaž Tollazzi. Non-motorized Participants on Alternative Types of Roundabouts. Nanoparticle Emissions From Combustion Engines 2014, 185 -199.
AMA StyleTomaž Tollazzi. Non-motorized Participants on Alternative Types of Roundabouts. Nanoparticle Emissions From Combustion Engines. 2014; ():185-199.
Chicago/Turabian StyleTomaž Tollazzi. 2014. "Non-motorized Participants on Alternative Types of Roundabouts." Nanoparticle Emissions From Combustion Engines , no. : 185-199.
Today, after many years of experience regarding roundabouts, there are still different ideas about the “ideal roundabout” with little consensus on the crucial effects of rules on how to negotiate intersections. The development of design rules and advice from an extensive body of research should allow civil and traffic engineers to produce the most effective forms of this junction type, even if for a variety of reasons this is not always carried out in practice.
Tomaž Tollazzi. Recent Alternative Types of Roundabouts. Nanoparticle Emissions From Combustion Engines 2014, 117 -155.
AMA StyleTomaž Tollazzi. Recent Alternative Types of Roundabouts. Nanoparticle Emissions From Combustion Engines. 2014; ():117-155.
Chicago/Turabian StyleTomaž Tollazzi. 2014. "Recent Alternative Types of Roundabouts." Nanoparticle Emissions From Combustion Engines , no. : 117-155.
Roundabouts are an increasingly common form of junction worldwide and their effective design requires detailed analysis of maximum vehicle throughput capacities. Since the 1970s, a series of models have been developed worldwide for an estimation of the capacity of roundabouts, almost all of which have relied upon extensive empirical data due to the complexity of the physical and behavioral processes affecting roundabout entry capacities. However, given the different fundamental principles (and particularly the geographical origins) of models, it is important to have a clear understanding of their limitations and their applicability within new contexts. These models are based on three main methodologies: empirical, gap acceptance and simulation. Due to their limitations, each of these methodologies on their own cannot completely explain the complex behavioral and physical processes involved at roundabout entries, hence all models require strong semi-empirical or fully-empirical bases using data obtained from their countries of origin.
Tomaž Tollazzi. General Criteria for Calculating the Capacities of Alternative Types of Roundabouts. Nanoparticle Emissions From Combustion Engines 2014, 171 -183.
AMA StyleTomaž Tollazzi. General Criteria for Calculating the Capacities of Alternative Types of Roundabouts. Nanoparticle Emissions From Combustion Engines. 2014; ():171-183.
Chicago/Turabian StyleTomaž Tollazzi. 2014. "General Criteria for Calculating the Capacities of Alternative Types of Roundabouts." Nanoparticle Emissions From Combustion Engines , no. : 171-183.
As pointed-out previously, today after many years of experience regarding roundabouts, there are different ideas about the ‘‘ideal roundabout’’. Therefore the development of design rules and advice from an extensive body of research should allow civil and traffic engineers to produce more effective forms of this junction type. It also needs to be stressed that the roundabout has been ‘‘at the development phase’’ since 1902, this development is still in progress, and one of the results of this progress is that several types of roundabouts are in worldwide usage today, called the “alternative types of roundabouts”. Some of them are already in frequent use all over the world, some of them are recent and have only been implemented within certain countries, and some of them are still at development phases. It is because of that we can call them “theoretical roundabouts” .
Tomaž Tollazzi. Alternative Types of Roundabouts at Development Phases. Nanoparticle Emissions From Combustion Engines 2014, 6, 157 -169.
AMA StyleTomaž Tollazzi. Alternative Types of Roundabouts at Development Phases. Nanoparticle Emissions From Combustion Engines. 2014; 6 ():157-169.
Chicago/Turabian StyleTomaž Tollazzi. 2014. "Alternative Types of Roundabouts at Development Phases." Nanoparticle Emissions From Combustion Engines 6, no. : 157-169.
In a comprehensive review of roundabouts it could firstly be beneficial to look at their origins. The conventions or rules of usage are as important as the layout. The history of roundabouts shows that these conventions must be conveyed by clear signs and warnings, and by the indications implicit within the layout. If this is done well then drivers will respond logically including moderating their speed.
Tomaž Tollazzi. Origins of Roundabouts. Nanoparticle Emissions From Combustion Engines 2014, 6, 1 -9.
AMA StyleTomaž Tollazzi. Origins of Roundabouts. Nanoparticle Emissions From Combustion Engines. 2014; 6 ():1-9.
Chicago/Turabian StyleTomaž Tollazzi. 2014. "Origins of Roundabouts." Nanoparticle Emissions From Combustion Engines 6, no. : 1-9.
Today, modern roundabouts exist in all European countries, and there are also several countries elsewhere in the world where they are numerous (the US, Australia, New Zealand, Israel, and Mexico).
Tomaž Tollazzi. Possible Ways of Roundabouts’ Development. Nanoparticle Emissions From Combustion Engines 2014, 201 -206.
AMA StyleTomaž Tollazzi. Possible Ways of Roundabouts’ Development. Nanoparticle Emissions From Combustion Engines. 2014; ():201-206.
Chicago/Turabian StyleTomaž Tollazzi. 2014. "Possible Ways of Roundabouts’ Development." Nanoparticle Emissions From Combustion Engines , no. : 201-206.
Analysis of literature shows that “modern roundabouts” nowadays exist in all European countries, as well as in more than 60 countries elsewhere in the world, so we could say that they are a world phenomenon.
Tomaž Tollazzi. Modern Roundabouts Design. Nanoparticle Emissions From Combustion Engines 2014, 6, 57 -116.
AMA StyleTomaž Tollazzi. Modern Roundabouts Design. Nanoparticle Emissions From Combustion Engines. 2014; 6 ():57-116.
Chicago/Turabian StyleTomaž Tollazzi. 2014. "Modern Roundabouts Design." Nanoparticle Emissions From Combustion Engines 6, no. : 57-116.
In the years from 1913 to 1914, Hellier suggested circular traffic systems at places, where several main roads would meet and the main connection of the circular system would prevent overload. At the conference of the local governmental committee on the subject of main roads in 1914, this idea was accepted as positive under the condition that the traffic requirements were met (every intersection should have sufficient empty space, and lawns alongside the intersections would be desirable). The initial phase of development in Europe was interrupted by the First World War. When the British Road Transport Board was set up in 1918, it was suggested that the roads of France should be the model for Europe. Gyratory systems were also used in the USA but there was great difficulty in regulating traffic, local ordinances were unenforceable and flouted, and there was no uniform rule of the road throughout the country. In 1924, at a US national conference, rights of way at intersections, and warning and stop signs were proposed. The “circus” idea continued to spread in the United Kingdom and was frequently recommended for busy junctions of more than four roads. During 1925-26 a lot of gyratory systems were introduced in London. These were simply one-way systems around existing squares with fairly sharp corners. Unfortunately some of the important principles implied in Henard’s concept, e.g. the entries into gaps during circling, operating over a short distance, were being lost. The transfer of these movements to a straight road caused differences in speeds at the conflict points but this may at first have been unimportant when all traffic speeds were quite low. The design was based solely on commonsense and experience [1].
Tomaž Tollazzi. First Developments of Different Roundabout Types. Nanoparticle Emissions From Combustion Engines 2014, 6, 11 -56.
AMA StyleTomaž Tollazzi. First Developments of Different Roundabout Types. Nanoparticle Emissions From Combustion Engines. 2014; 6 ():11-56.
Chicago/Turabian StyleTomaž Tollazzi. 2014. "First Developments of Different Roundabout Types." Nanoparticle Emissions From Combustion Engines 6, no. : 11-56.