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1

Safety evaluation of turbo roundabout considering autonomous vehicles operation

Severino Alessandro, Pappalardo Giuseppina, Trubia Salvatore

Archives of Civil Engineering

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2021

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Vol. 67, nr 1

439--460

EN

A microsimulation approach was carried out in this paper to evaluate the safety performance of turbo roundabouts in which the "CAVs" of connected autonomous vehicles are mixed with the "CVs" of conventional vehicles the research aims to evaluate the advantages in terms of safety and performance of turbo roundabouts. The paper shall also lead to describe the methodological path followed to build VISSIM models of turbo roundabout changing O_D matrix as real case applications, to calibrate the simulation models, and to estimate the potential conflicts when the percentages of CAVs are introduced into the traffic mix. The results, in accordance with the existing bibliography, have shown that the safety levels and the parameters that determine an improvement in the service level in a turbo roundabouts are significantly influenced not only by the geometric characteristics, but also by the distribution of vehicular flows. Therefore, it follows that in absence of crash data including CAVs, the surrogate measures of safety must be considered a strong approach to evaluate the safety performance of a roundabout so far, any road entity.

2

Approximation of the offset curves in the formation of turbo roundabouts

Borowska A.

Journal Biuletyn of Polish Society for Geometry and Engineering Graphics

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2018

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Vol. 31

53--60

PL

W pracy przedstawione są rezultaty analizy numerycznej dla problemu aproksymacji krzywej offsetowej off(c(t); s) spirali Archimedesa c(t) (o odległości s) przez inną spiralę Archimedesa c1(t). Szczególnie rozważane były te spirale, które mogą posłużyć do kształtowania rond turbinowych. Artykuł zawiera matematyczne fakty i wyniki obliczeń pomocne w projektowaniu rond turbinowych kształtowanych za pomocą spirali Archimedesa.

EN

This article describes the results of numerical analysis of the following problem: the approximation of the offset curve off(c(t); s) of the Archimedean spiral c(t) at distance s by the other Archimedean spiral c1(t). We focus on the spirals which can be used to shape the turbo roundabouts. The paper contains mathematical facts which are helpful in designing the turbo roundabouts formed by means of the Archimedean spiral.

3

Approximation of the ellipse offset curves in turbo roundabouts design

Borowska A.

Journal Biuletyn of Polish Society for Geometry and Engineering Graphics

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2018

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Vol. 31

43--51

PL

Eliptyczne ronda turbinowe są bardziej bezpieczną i efektywniejszą alternatywą dla standardowych rond wielopasmowych. W pracy przedstawiono wyniki analizy numerycznej dla problemu aproksymacji krzywych offsetowych off(el(a, b); s) danej elipsy el(a, b) o odległości s przez elipsę el(a-s, b-s) oraz el(a+s, b+s). Rozważamy elipsy, które mogą posłużyć do kształtowania rond turbinowych. Przetestowano, dla których wartości parametrów s (szerokość pasa ruchu) i e (mimośród) maksymalne odchylenie krzywej offsetowej elipsy od elipsy el1 (el2) nie przekracza dokładności tyczenia krzywych w terenie.

EN

The elliptical turbo roundabouts are a safer and more effective alternative to the known multi-lane roundabouts. This paper contains the results of numerical analysis for the problem of approximation of the offset curves off(el(a, b); s) of an ellipse el(a, b) at distance s by ellipses el1(a+s, b+s) and el2(a-s, b-s). We considered the ellipses which can be used to shape the turbo roundabouts. It was tested for which parameter values s (the width of the lane) and e (eccentricity) the maximum deviation of the ellipse offset curve from the ellipse el1 (el2) does not exceed the accuracy of the delineating the curves in the terrain.

4

The road safety at turbo roundabouts in Poland

Macioszek E.

Archives of Transport

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2015

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Vol. 33, iss. 1

57--67

EN

There are to two groups of turbo roundabouts used currently in Poland. The first group is turbo roundabouts with geometry and traffic organization designed following the model of Dutch turbo roundabouts with raised lane dividers. The other group is turbo roundabouts with traffic organization which entirely or partly corresponds to traffic organization of conventional turbo roundabouts, but with lane dividers not present, with their function performed by a single continuous line of P-2 type. Turbo roundabouts in the world are considered as solutions which are characterized by a high level of road safety and allow for effective flow at substantial traffic intensities. The data about turbo roundabouts in Poland analysed by the author show that there are substantially more turbo roundabouts without raised lane dividers. The paper attempts to answer to the question of whether turbo roundabouts with lane dividers in the form of a single continuous line ensure the appropriate level of road safety. Furthermore, the comparison of the level of road safety in turbo roundabouts equipped in raised lane dividers with turbo roundabouts with lane separators in the form of continuous line revealed that turbo roundabouts with raised lane dividers are safer solutions than turbo roundabouts with traffic lane dividers in the form of continuous line.