Recent trends in air transport sustainibility

The target of this paper is to analyse the main elements of Air Transport sustainability, studying their evolution during the last years and establishing the future prevalent trends, which might be modified by the application of the adequate policies. Air Transport sustainability is considered as integrated by five basic characteristics: physical accessibility, economic affordability, safety, security and environmental impact. Each one of them has its own influence on the development of this transportation mode and all of them are required in order to achieve a sustainable development. After defining the structural elements of the five characteristics and the corresponding quantitative indicators, the paper studies the recent evolution of such indicators and extrapolates the most likely future trends, having taken into account the most relevant limitations presently existent or potentially appearing in the near future. The most important policies being presently studied (future aircraft designs, infrastructure developments, potential safety and security new rules and tentative environmental action programs) are evaluated, considering the potential repercussions on sustainability progress. Some combinations of them are suggested as the most efficient alternatives for preserving the sustainable development of XXI century air transport.DOI: http://dx.doi.org/10.4995/CIT2016.2016.2150

Finding the right RoPax vessel size and freight price. A coste and mode choice model

Motorways of the sea operated as RoPax services are natural competitors with only-road freight haulage transportation. Cost, time and quality perceived are the determinants that make transporters and shippers use one route or another. This research considers the role that shipping companies and their ship deployment and pricing strategy have in the equation, as incentives for modal shift from road to sea. A model of the ships and transporter costs is developed considering different business models for the transporter (accompanied versus unaccompanied cargo) followed with a discrete choice model that, once calibrated, allows to test the influence that variables such as frequency, ship size and commercial speed might play into the competitiveness of a shipping line. As a result, different pricing strategies for the shipping line are developed and the characteristics of the optimal shipping line for each of them are found, to either maximize the profit of the shipping company or the modal shift.DOI: http://dx.doi.org/10.4995/CIT2016.2016.4148

An Evaluation of the Resilient Modulus and Permanent Deformation of Unbound Mixtures of Granular Materials and Rubber Particles from Scrap Tyres to Be Used in Subballast Layers

Over the last years rubber from scrap tyres has been reused in different civil works such as road embankments and railway platforms due to its resilient properties, low degradation and vibration attenuation. Unfortunately, this issue is still scarce. For instance, in Spain about 175.000 tonnes of scrap tyres were collected in 2014, of which only 0.6% were reused in civil works. Aiming to contribute to the reutilisation of large quantities of this waste material, this paper focuses on the analysis of unbound mixtures of granular materials with different percentages of rubber particles to be used as subballast layers. Mixtures are tested under cyclic triaxial tests so as to obtain their resilient modulus and evaluate their permanent deformations. It is found that as the rubber content increases, the resilient modulus decreases and the permanent deformation increases. Taking into account the usual loads transmitted to the subballast layer, the optimum rubber content that does not compromise the behaviour of the mixture is set in a range between 2.5% and 5% in terms of weight.DOI: http://dx.doi.org/10.4995/CIT2016.2016.4231

El bike-sharing como herramienta de sostenibilidad para áreas metropolitanas

El área metropolitana de Valencia dispone de un servicio de bicicleta compartida interoperable entre los distintos municipios, constituyendo una opción de transporte siempre disponible que fomenta los viajes intermodales y que vertebra el territorio.DOI: http://dx.doi.org/10.4995/CIT2016.2016.4259

Pain and Joy of a Panel Survey on Transport Studies

Over ten years ago, it was established that the most frequent reason that motivates a panel survey on transport studies is theevaluation of a change in the transportation system, or a specific transportation-planning project, especially when the projectinvolves novel elements. From a statistical viewpoint, a panel survey has the definite advantage to offer more accurate estimatesof changes than cross-sectional surveys for the same sample size. Observing travel patterns of individuals and households overseveral consecutive days, has offered insights into activity scheduling and travel planning. Variability in travel patterns hasimportant policy implications as well, but how much effort is worth to design a panel survey?To evaluate the effects of the transport policies introduced in Madrid during the last five years, a ‘short-long’ panel survey wasbuilt, based on a sample of a Madrid-worker subpopulation most affected by those recent changes in transport policy. The paperdescribes both the design and construction of the panel based on GPS technology, and presents some results based on an analysisof its two waves; for example, it registered an increment of public transport use and walking trips in 10%. The panel overcomesthe known attrition problem thanks to providing incentives, maintaining contact, using the same interviewer for the samerespondents, and conducting face-to-face interviews.DOI: http://dx.doi.org/10.4995/CIT2016.2016.4056

Saturation flow mathematical model based on multiple combinations of lane groups

The ideal value of the traffic stream that can pass through an intersection is known as the saturation flow rate per hour on vehicle green time. The saturation flow is important in the understanding of the traffic light cycle and from there the understanding the Level of Service. The paper wishes to evaluate through a series of applied mathematical methods the effect of different lane grouping and critical lane group concept on the saturation flow rate. The importance of this method is that it creates a base for a signalized intersections timing plan.DOI: http://dx.doi.org/10.4995/CIT2016.2016.4254

VELOCIDAD DE OPERACIÓN DE VEHÍCULOS LIGEROS EN CURVAS DE CARRETERAS CONVENCIONALES

La velocidad de operación es uno de los factores más estudiados en el análisis de la seguridad vial por su relación con la siniestralidad. En la fase de explotación es relativamente sencillo calcular la velocidad de operación a partir de datos empíricos, pero, en las fases de planeamiento y de proyecto, sólo será posible estimarla. Numerosos autores han modelizado la velocidad de operación de vehículos ligeros en curvas de carreteras convencionales considerando su velocidad mínima. Algunos a partir de observaciones en aquellos puntos de la carretera más significativos como el punto medio de la curva (velocidad mínima), otros a partir de datos continuos utilizando, por ejemplo, dispositivos GPS. La mayoría de los modelos que estiman esta velocidad se basan únicamente en el percentil 85 de la distribución o en su velocidad media. Además, la mayoría de los estudios asumen que sus datos se distribuyen según una normal sin, en muchos casos, comprobar dicha hipótesis. El objetivo de este estudio es analizar la distribución de la velocidad desarrollada por vehículos ligeros circulando en condiciones de flujo libre en curvas de carreteras convencionales. Para ello, la investigación se basa en determinar si los datos de velocidad de 63 curvas disponibles de una base de más de 16.000 vh·km se distribuyen según una normal, y en el análisis del comportamiento de la media y la desviación típica de la distribución de velocidades en curvas. Se ha concluido que la distribución normal no es la que mejor se ajusta al comportamiento de la velocidad en la mayoría de los casos.DOI: http://dx.doi.org/10.4995/CIT2016.2016.4112

Contribución de las aplicaciones móviles a la Seguridad vial. Drive Smart como ejemplo de aplicación.

En los últimos años han proliferado las aplicaciones móviles que contribuyen, en diferentes aspectos, a mejorar la movilidad. En este contexto, se ha desarrollado la aplicación móvil Drive Smart, con el objetivo de analizar y mejorar el comportamiento del usuario al volante. A través de la utilización de dicha aplicación se obtiene un conjunto de datos que se transforman en un paquete de incidencias en la conducción, siendo éstas: velocidad, aceleración, frenada, paso por curva y anticipación al tráfico. Drive Smart analiza los eventos de tráfico registrados en el contexto en el que han ocurrido y como parte de una maniobra, más allá de la individualidad de un evento. Además, tiene la capacidad de asistir al conductor, dándole un informe posterior a su conducción que le sirva de autoformación y con consejos prácticos orientados a mejorar la conducta en temas particulares, mediante mensajes específicos de distintas tipologías (jurídico, eficiencia y sensibilizador). A través de este proyecto, se pretende demostrar la viabilidad y utilidad de los modernos mecanismos telemáticos en combinación con el estudio psicosociológico y las diversas técnicas de análisis estadístico de datos basados en Machine Learning. Los datos obtenidos de la aplicación móvil junto con datos sociodemográficos permiten obtener las principales variables de movilidad, además, pueden utilizarse para definir la base algorítmica en futuros estudios con mayor calado, teniendo una matriz estadística preliminar que permita generar procesos paralelos en el futuro.DOI: http://dx.doi.org/10.4995/CIT2016.2016.3472

Public transport traffic management systems simulation in Craiova city

Urban transport is a comprehensive and dynamic mechanism. Therefore, all the problems for improving and reorganization of the system can be examined only in the light of a systemic approach. Currently, public passenger transport is one of the most important branches of the urban development in cities and metropolis. Public passenger transport activity and all the steps taken to improve that activity are considered to be of great social importance. In the current stage of city development, one of the main tasks is to create a public passenger transportation system that is safe, affordable, economical, reliable and environmentally friendly. The important role of passenger transport in the city's economy and achieving important social services to the population, dictates the need to introduce measures in the system that are harmonious, balanced and effective. This can only be done, in the context of current development, only after the system as a whole is tested extensively through special traffic and management software.DOI: http://dx.doi.org/10.4995/CIT2016.2016.4255

FEASIBILITY STUDY FOR WATERWAY INFRASTRUCTURE: INTERNATIONAL OVERVIEW AND METHODOLOGICAL RECOMMENDATIONS

The context in which the waterway transportation is in Brazil makes clear the development need of specific methodologies for the sector planning. This paper aims to compare the methods of analysis of technical, economic and environmental viability, adopted in Europe, United States and Brazil, listing the best practices and possible improvements of the method adopted in Brazil. The analysis of the documents was based on comparative method, seeking the common elements from its attributes. Each document was analysed in terms of: its structure; type of impacts; required indicators on each impact analysis; reference values for classification of indicators; and the form of integrated analysis of different impacts. The study suggests the inclusion of certain changes in the methodology of calculation and in its combination of tools and parameters used in the measurement of fiscal impacts on the comparative analysis of standard models usually adopted in the United States, Europe and the World Bank.DOI: http://dx.doi.org/10.4995/CIT2016.2016.4101