The authors have already developed and studied the Two-Geometry Roundabouts in terms of design principles. This paper in fact is the natural extension a previous article by Pratelli et al., 2022, in ...which the authors discussed the main concepts of the Two-Geometry Roundabouts and the details that determine their success. However, when someone talks about roundabouts in general, it is also essential to specify which respective capacity model is most suitable. The Highway Capacity Manual (HCM6th) provides a popular method for estimating the capacity of conventional roundabouts. Nevertheless, the Two-Geometry Roundabouts are classified as unconventional roundabouts, and therefore this paper aims to answer the following crucial question: “Which capacity model should be used to calculate a Two-Geometry Roundabout?”. Firstly, the impositions of the Italian guidelines, where all roundabouts with a non-circular shape or with an inscribed diameter greater than 50 meters are defined as unconventional, are described. The achieved empirical results in respect to some test has compared with those otherwise obtained through the HCM6th methodology. Next, two popular methods suitable for calculating the capacity of Two-Geometry Roundabouts are resumed, namely the SETRA method and the Brilon-Wu method. These two are chosen because on the one hand SETRA directly requests dimensions of some selected geometric components; while on the other hand, the Brilon-Wu approach is based only on a few macro characteristics such as the number of entry/circulation lanes and the values of the gap acceptance parameters. Then, the successive section is devoted to comparing performance between a Traditional circular Roundabout and a Two-Geometry Roundabout, designed for the same intersection. This comparison was carried out through the use of experimental results obtained with a dynamic simulation approach made with Aimsun software. Finally, the paper ends with a brief discussion on some possible insights framed in a further development of the research, which could involve the safety models of Two-Geometry roundabouts, and their possible extension to roundabout corridors.
Two-Geometry Roundabouts: Design Principles Pratelli, Antonio; Souleyrette, Reginald R.; Brocchini, Lorenzo
Transportation research procedia,
2022, 2022-00-00, Letnik:
64
Journal Article
Odprti dostop
Although multi-lane concentric roundabouts have a greater capacity than single-lane roundabouts, they may encourage increased driving speeds and decrease in safety. Furthermore, lane changing is ...possible in multi-lane roundabouts, thus increasing the risk of crashes. To address these drawbacks, the authors present the “Two-Geometry” Roundabout. This type of roundabout discourages lane changing within the roundabout, lowers driving speed through the roundabout, and facilitates the manoeuvres of larger and longer vehicles. The paper discusses the concept of the Two-Geometry Roundabout and outlines its principal advantages. We first delineate characteristics of single-roundabouts and multi-lane roundabouts, focusing on the problems of the latter. Next, the development, main characteristics and typologies of Two-Geometry Roundabouts are illustrated (with some examples attached); therefore, we focus on the positive effects of the Two-Geometry Roundabout with particular attention on heavy vehicles. Finally, we present methods for calculating the capacity of the Two-Geometry Roundabout and conclude the paper.
This article is the second of two papers on a topic gaining ground in traffic and transport engineering, namely Dynamic Planning of Vertical Road Signs Maintenance. In particular, this second paper ...describes the development of the forecasting model and then the analysis of data and the statistical evidence. In detail, starting from the data, a comparison was made between the values measured and those prescribed by the reference standard (UNI EN 12899-1: 2008) according to the category of retroreflective film. Analysing the data macroscopically, it emerged that 75% of the signs met the minimum retroreflective requirements, in compliance with 25% did not respect them. Subsequently, a suitable database was selected for the development of the forecast model, excluding from the sample the vertical signs still under guarantee and proceeding with the correlation between the age of the sign and the retroreflection value found. A statistical analysis of the observed data was then carried out. In detail, the following were carried out: the two-sample t-test, used to verify the statistical significance of the average age difference relating to signs that meet or do not meet the minimum retroreflective requirements; the discriminant analysis with cross-validation, used for the development of the forecasting model; the linear regression, used to evaluate the variation of the retroreflective coefficient as a function of the age of the sign. The summary of the results and the insights for further research developments are made in the conclusions.
This article is the first of two papers on a topic gaining ground in traffic and transport engineering, namely Dynamic Planning of Vertical Road Signs Maintenance. In particular, this first paper ...describes the methodologies used in determining the current state, the position, the type, the state of conservation and the efficiency of vertical road signs in the city of Forte dei Marmi (Tuscany, Italy). The ultimate goal is to set up a dynamic GIS-based road vertical signs archive and subsequently develop a forecast model. Such an operational procedure can be seen as a useful tool for setting up a Dynamic Maintenance Plan for all vertical signs along the roads of the municipal area. The methodology followed is the following: once the area of interest has been defined, the retroreflection parameter of the 752 vertical signs present in the area was measured using a retroreflectometer, recording the georeferenced data in a specific GIS database. This hands-on approach allows for both adding and removing a given sign, as well as sorting all monitored signs by age and efficiency in a dynamic operational maintenance view. Hence, the development of the forecasting model has been done, however, for this part reference should be made to the second paper. In the final part of this article, the concluding chapter relating to the creation of a dynamic maintenance plan and the conclusions on the methodology used and on possible ideas for further research developments have been included.
The modern distribution of goods is highly complex, as it supports a closely linked globalized world. In the development of port terminals, competition is no longer only at the level of services. The ...increase in maritime transport and demand/supply in the hinterlands, with ensuing problems of capacity, distribu- tion and movement, have called for renewed attention on adequate structures and infrastructures. This evolution, enabled by technology, commercial interests and public policies, can be considered as a stage in the ongoing development of containerization and intermodal transport. At this stage, it is important to consider port terminals and maritime navigation networks as a system, together with terrestrial goods transport. Increasingly, regions are developing so-called dry or inland ports, to better serve the demand. We set out to define a sustainable model for dry ports, beginning with a review of relevant literature focused on Italian, Dutch and selected USA examples. We first define dry port, in the context of intermodal transport, ports in general and inland ports. Our investigation led to the identification of management tools and best practices. We report on visits and interviews to selected inland ports and identify key dry port activities, applications of innovative technologies and implications for different modes of transport. For the three countries studied, we identify strengths and weaknesses related to infrastructure, structures, internal organization of yard, types of imported and exported goods, transport methods and related travel times and costs. In regards to resilience and sustainability, vulnerabilities such as congestion, climate issues and cyber-attacks are considered. Finally, a maturity model for as- sessing dry ports is proposed.
AbstractBy comparing model results from tests of steady and oscillatory flows over a submerged bar (of interest for both riverine and marine environments), we highlight similarities and differences ...between a state-of-the-art Boussinesq model and a recently developed non-hydrostatic, quasi-three-dimensional (3D) model. To make the comparison as clean as possible, the complexities due to breaking-induced turbulence are avoided by suitably tuning the flow strength. Although the main flow features are similarly described by the two models, the non-hydrostatic model predicts the occurrence of extra, small-scale stationary oscillations on top of a submerged obstacle in the case of a steady current. This is attributed to a pattern of alternating upward and downward vertical velocity over the sill top, presumably due to rapidly converging flows as they climb over the submerged obstacle. The non-hydrostatic model overall allows for a more complete representation of flow dynamics in the vertical direction, with respect to the Boussinesq-type solver. This becomes necessary when tackling fundamental and applicative problems characterized by intense vertical flows (e.g., interactions of fluids with structures).
Tsunamis in the Mediterranean Sea have been increasingly investigated recently due to past destructive events. We present a novel operational approach for evaluating tsunami‐induced inundation, based ...on a generalization of Green's law and a chain of intermediate and small‐scale simulations. At the intermediate level, simulations with a linear solver are made to identify the distribution of a novel parameter, namely α, condensing all nearshore wave transformations other than shoaling. α represents a proxy for coastal susceptibility to the tsunami impact. Small‐scale modeling of coastal flooding performed at locations for which a DTM is freely available, at the Esaro river estuary (Calabria) and in Bari (Apulia), yields inundation levels that compare well with those obtained via intermediate‐scale modeling, with a saving in computational time of about 41%. This demonstrates the value of α to “scale” the offshore wave input and reduce computational effort to evaluate flooding at regional scale.
Plain Language Summary
An interest in studying the consequences of tsunamis has arisen also for the Mediterranean Sea in the last decades. In this manuscript we present a method for the evaluation of potential coastal inundation caused by the impact of tsunamis. The method exploits a chain of numerical simulations of wave propagation to move the tsunami from the source region down to the investigated coasts. The inundation estimate makes use of a simple parameter, named α, devised to encapsule all the transformation processes the tsunami undergoes in its travel from intermediate waters to the coastline. We apply the method to portions of the southern Italian coast with a prototype tsunami event, and we see that inundation levels achieved with faster, small‐scale simulations compare well with those obtained with longer, intermediate‐scale simulations. The method can be helpful as an implementation in recent tsunami warning systems developed to warn coastal communities on impending threats.
Key Points
A modeling chain approach for the evaluation of tsunami inundation is described and applied to the coasts of South Italy
The method exploits a semi‐empirical extension of the classical Green's law to general bathymetries, and dedicated numerical simulations
The method allows for transposing computational effort from intermediate to shallow waters
Video-monitoring can be exploited as a valuable tool to acquire continuous, high-quality information on the evolution of beach morphology at a low cost and, on such basis, perform beach resilience ...analyses. This manuscript presents preliminary results of an ongoing, long-term monitoring programme of five sandy Italian beaches along the Adriatic and Tyrrhenian sea. The project aims at analyzing nearshore morphologic variabilities on a time period of several years, to link them to resilience indicators. The observations indicate that most of the beach width variations can be linked to discrete variations of sandbar systems, and most of all to an offshore migration and decay of the outermost bars. Further, the largest net shoreline displacements across the observation period are experienced by beaches with a clear NOM (Net Offshore Migration)-type evolution of the seabed.
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